

<!-- formatList: 

 Array
(
    [5 users] =&gt; Array
        (
            [slug] =&gt; 5 users
            [parent] =&gt; 
            [name] =&gt; 5 users
            [canonical] =&gt; five users
            [see] =&gt; 
            [description] =&gt; 
        )

    [a-b test] =&gt; Array
        (
            [slug] =&gt; a-b test
            [parent] =&gt; 
            [name] =&gt; A&amp;ndash;B test
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; A&amp;ndash;B test is a form of automated {{usability evaluation}}, used particularly on the web. It involves releasing two (or more) minor variants of an application, A and B, for example two different colour schemes or positions for a {{call-to-action button}}. Metrics are gathered automatically, such as {{click-through rate}} or {{time on page}}, and these are used to determine which of the variants is best.
        )

    [a-b testing] =&gt; Array
        (
            [slug] =&gt; a-b testing
            [parent] =&gt; 
            [name] =&gt; a-b testing
            [canonical] =&gt; a-b test
            [see] =&gt; 
            [description] =&gt; 
        )

    [a---b test] =&gt; Array
        (
            [slug] =&gt; a---b test
            [parent] =&gt; 
            [name] =&gt; a---b test
            [canonical] =&gt; a-b test
            [see] =&gt; 
            [description] =&gt; 
        )

    [a---b testing] =&gt; Array
        (
            [slug] =&gt; a---b testing
            [parent] =&gt; 
            [name] =&gt; a---b testing
            [canonical] =&gt; a-b test
            [see] =&gt; 
            [description] =&gt; 
        )

    [acm chi] =&gt; Array
        (
            [slug] =&gt; acm chi
            [parent] =&gt; 
            [name] =&gt; ACM CHI
            [canonical] =&gt; 
            [see] =&gt; chi conference
            [description] =&gt; 
        )

    [acm conference] =&gt; Array
        (
            [slug] =&gt; acm conference
            [parent] =&gt; 
            [name] =&gt; ACM conference
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; ACM is one of the major international organisations for computing. ACM conferences such as {{CHI}} are often among the most prestigious in their areas.
        )

    [borrowed methods] =&gt; Array
        (
            [slug] =&gt; borrowed methods
            [parent] =&gt; 
            [name] =&gt; borrowed methods
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; Methods derived from  other disciplines, for example psychology, where controlled experiments typically have a single cause and are in highly controlled environments. Care must be taken, because interaction studies, even in lab settings, almost always have multiple causes and open situations.
        )

    [chi] =&gt; Array
        (
            [slug] =&gt; chi
            [parent] =&gt; 
            [name] =&gt; CHI
            [canonical] =&gt; chi conference
            [see] =&gt; 
            [description] =&gt; 
        )

    [chi conference] =&gt; Array
        (
            [slug] =&gt; chi conference
            [parent] =&gt; 
            [name] =&gt; CHI conference
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; Annual ACM Conference on Human Factors in Computing Systems
        )

    [claims analysis] =&gt; Array
        (
            [slug] =&gt; claims analysis
            [parent] =&gt; 
            [name] =&gt; claims analysis
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; A method developed by Carroll and Rosson, which seeks to better integrate activities directed at understanding with those directed at design. DOI: &lt;doi&gt;10.1145/146802.146834&lt;/doi&gt;
        )

    [cognitive load] =&gt; Array
        (
            [slug] =&gt; cognitive load
            [parent] =&gt; 
            [name] =&gt; cognitive load
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; The amount of mental resources (e.g. memory, attention) needed for a task or activity.
        )

    [conscious mind] =&gt; Array
        (
            [slug] =&gt; conscious mind
            [parent] =&gt; 
            [name] =&gt; conscious mind
            [canonical] =&gt; conscious thinking
            [see] =&gt; 
            [description] =&gt; 
        )

    [conscious thinking] =&gt; Array
        (
            [slug] =&gt; conscious thinking
            [parent] =&gt; 
            [name] =&gt; conscious thinking
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; These are the thoughts that you are explicitly aware of having: what you would answer if asked &quot;What are you thinking of now?&quot;. The conscious mind is extremely powerful, allowing us to think rationally and logically, but it is also limited. In particular, your conscious system of thought likes to have a single model of the world and is really bad at probability. Contrast with {{subconscious reactions}}.
        )

    [constant area visualisation] =&gt; Array
        (
            [slug] =&gt; constant area visualisation
            [parent] =&gt; 
            [name] =&gt; constant area visualisation
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; A visualisation for hierarchical data in which the area of each part reflects the number or size of the items it represents (e.g. a {{TreeMap}} or {{PieTree}})
        )

    [controlled environments] =&gt; Array
        (
            [slug] =&gt; controlled environments
            [parent] =&gt; 
            [name] =&gt; controlled environments
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; In physics and other sciences, scientists use very pure substances with very precise instruments to reduce the variability in a study. In HCI we can sometimes emulate this, controlling conditions to reduce the variability in our study ({{reduce noise}}). For example, in a user test we might ask people to use a mobile phone to perform the same tasks in the same location with similar levels of sound and distractions. The downside of this is that it can sometimes reduce {{ecological validity}}, making the resulting conditions less like the real world.
        )

    [controlled experiment] =&gt; Array
        (
            [slug] =&gt; controlled experiment
            [parent] =&gt; 
            [name] =&gt; controlled experiment
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; Controlled experiments follow a strict protocol, a predefined number of trials, often in a laboratory setting. In HCI, controlled experiments may influence results. For example, experts may behave more like novices in the artificial  environment of a lab experiment, being more careful about their actions and monitoring the results. Typically, controlled experiments have to sacrifice {{ecological validity}}, being less like the equivalent real-world activity. Contrast with {{ethnographic methods}} and {{in-the-wild}} studies. 
        )

    [controlled laboratory experiments] =&gt; Array
        (
            [slug] =&gt; controlled laboratory experiments
            [parent] =&gt; 
            [name] =&gt; controlled laboratory experiments
            [canonical] =&gt; controlled experiment
            [see] =&gt; 
            [description] =&gt; 
        )

    [controlled tasks] =&gt; Array
        (
            [slug] =&gt; controlled tasks
            [parent] =&gt; 
            [name] =&gt; controlled tasks
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; Restricting tasks to enable more valid study of individual variables: for example, participants are in a real situation, but instead of doing what they like, they are given a scripted task to perform. While some realism is lost in terms of the chosen task, this increases the level of {{ecological validity}} in the environment.
        )

    [coping mechanisms] =&gt; Array
        (
            [slug] =&gt; coping mechanisms
            [parent] =&gt; 
            [name] =&gt; coping mechanisms
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; The resources that people draw on when they find ways to manage a difficult task, whether consciously or unconsciously. While this is useful for getting a job done, for the designer it can mean that usability problems may be hidden. {{Distractor tasks}} are one way to deal with this.
        )

    [data journals] =&gt; Array
        (
            [slug] =&gt; data journals
            [parent] =&gt; 
            [name] =&gt; data journals
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; These are academic journals that primarily publish documented data. This is in contrast to traditional journals, which may publish data, but only as some form of addendum to a paper that is primarily about the analysis and interpretation of the data.
        )

    [data detector] =&gt; Array
        (
            [slug] =&gt; data detector
            [parent] =&gt; 
            [name] =&gt; data detector
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; A data detector scans text for terms such as names, post codes or numbers in order to make live links to related information, or in other ways help the user.  They may use lookups in dictionaries or databases for {{named entiries}} (movie titles, names of places), {{regular expressions}} for pattern structured items (such as book ISBNs or telephone numbers), or more complex rules.  You probably have encountered datadetectors in email messages identifying URLs to make them live links, or dates and times to suggest adding a caneldar event. 
        )

    [data detectors] =&gt; Array
        (
            [slug] =&gt; data detectors
            [parent] =&gt; 
            [name] =&gt; data detectors
            [canonical] =&gt; data detector
            [see] =&gt; 
            [description] =&gt; 
        )

    [demonic intervention] =&gt; Array
        (
            [slug] =&gt; demonic intervention
            [parent] =&gt; 
            [name] =&gt; demonic intervention
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; Creating extreme experimental situations to {{increase effect}} size.
        )

    [demonic interventions!] =&gt; Array
        (
            [slug] =&gt; demonic interventions!
            [parent] =&gt; demonic interventions
            [name] =&gt; 
            [canonical] =&gt; demonic intervention
            [see] =&gt; 
            [description] =&gt; 
        )

    [demonic interventions] =&gt; Array
        (
            [slug] =&gt; demonic interventions
            [parent] =&gt; 
            [name] =&gt; demonic interventions
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; 
        )

    [design space] =&gt; Array
        (
            [slug] =&gt; design space
            [parent] =&gt; 
            [name] =&gt; design space
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; The range of alternative design choices that can be combined in different ways, for example synchronous vs asynchronous, domain specific vs generic. The design space may be represented in a matrix of different semi-independent  choices, but also may be more complex.
        )

    [ecological validity] =&gt; Array
        (
            [slug] =&gt; ecological validity
            [parent] =&gt; 
            [name] =&gt; ecological validity
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; The ecological validity of a test, study or experiment is the extent to which it is like the real world. Performing a {{controlled experiment}} in a laboratory would usually have low ecological validity, whereas an {{ethnographic study}}, observing people in their own workplace, would have high ecological validity.
        )

    [ecologically meaningful] =&gt; Array
        (
            [slug] =&gt; ecologically meaningful
            [parent] =&gt; 
            [name] =&gt; ecologically meaningful
            [canonical] =&gt; ecological validity
            [see] =&gt; 
            [description] =&gt; 
        )

    [ecologically valid] =&gt; Array
        (
            [slug] =&gt; ecologically valid
            [parent] =&gt; 
            [name] =&gt; ecologically valid
            [canonical] =&gt; ecological validity
            [see] =&gt; 
            [description] =&gt; 
        )

    [elderly users] =&gt; Array
        (
            [slug] =&gt; elderly users
            [parent] =&gt; 
            [name] =&gt; elderly users
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; Older users often have different characteristics from younger ones: for example, on average poorer eyesight or problems with short-term memory. However, this said, there is also a wide variation between different users of any age group and, of course, similarities between ages; for example, many younger people have poor eyesight.
        )

    [empirical evaluation] =&gt; Array
        (
            [slug] =&gt; empirical evaluation
            [parent] =&gt; 
            [name] =&gt; empirical evaluation
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; This is when a system or aspect of a system is evaluated through actual data, whether gathered in a {{laboratory experiment}} or {{in the wild}}. Alternatives would be to use some form of {{expert evaluation}} or {{theoretical analysis}}.
        )

    [ethnographic methods] =&gt; Array
        (
            [slug] =&gt; ethnographic methods
            [parent] =&gt; 
            [name] =&gt; ethnographic methods
            [canonical] =&gt; ethnography
            [see] =&gt; 
            [description] =&gt; 
        )

    [ethnographic study] =&gt; Array
        (
            [slug] =&gt; ethnographic study
            [parent] =&gt; 
            [name] =&gt; ethnographic study
            [canonical] =&gt; ethnography
            [see] =&gt; 
            [description] =&gt; 
        )

    [ethnography] =&gt; Array
        (
            [slug] =&gt; ethnography
            [parent] =&gt; 
            [name] =&gt; ethnography
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; A form of {{qualitative research}} based strongly on observation of real situations. A particular focus of {{ethnography}} is to understand a situation from the point of view of the people involved, to become encultured into their patterns of thought, rather than to impose one's own models, theories or values. Experienced ethnographers typically resist any attempt to claim {{generalisability}} of their work, emphasising the unique nature of each situation and context. However, in practice they are very good at bringing out aspects of the situation that inform similar situations elsewhere.
        )

    [experimental error] =&gt; Array
        (
            [slug] =&gt; experimental error
            [parent] =&gt; 
            [name] =&gt; experimental error
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; No interesting experiment gives a precise and unambiguous result; there is always a margin of error. For example, if you sample 100 people out of the workforce of a large company, by chance you might choose those who are unusually tall or short, or those who are unusually happy or unhappy with the systems they use. Furthermore, there may be limits to the accuracy of the measurement devices you use, although this is more of a problem in physical rather than human sciences. Where the error is due to random effects, and these are understood, you may be able to estimate the margin of error, for example the {{standard error}} of the mean.
        )

    [experimenter effects] =&gt; Array
        (
            [slug] =&gt; experimenter effects
            [parent] =&gt; 
            [name] =&gt; experimenter effects
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; A particular type of {{context effect}} where something about the experimenter (for example their mood) affects the responses of the subjects to the tasks.
        )

    [expert evaluation] =&gt; Array
        (
            [slug] =&gt; expert evaluation
            [parent] =&gt; 
            [name] =&gt; expert evaluation
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; Evaluation carried out by a usability expert rather than an actual user. These are often used for early assessment of a system to avoid the costs of a full {{usability evaluation}}. Note that the term 'expert' here refers to usability or UX expertise, not expertise in the domain of the system. Examples of expert evaluation include {{cognitive walkthrough}} and {{heuristic evaluation}}.
        )

    [expert slip] =&gt; Array
        (
            [slug] =&gt; expert slip
            [parent] =&gt; 
            [name] =&gt; expert slip
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; An expert slip is a form of error that is more frequently performed by an expert. Whilst novices may make errors due to lack of knowledge or practice, expert slips are often about performing tasks quickly or with less attention. They are typically infrequent, but may be more damaging and may be noticed far later as experts do not usually need to check the results of their actions as often as novices.
        )

    [file tree] =&gt; Array
        (
            [slug] =&gt; file tree
            [parent] =&gt; 
            [name] =&gt; file tree
            [canonical] =&gt; file tree visualisation
            [see] =&gt; 
            [description] =&gt; 
        )

    [file tree visualisation] =&gt; Array
        (
            [slug] =&gt; file tree visualisation
            [parent] =&gt; 
            [name] =&gt; file tree visualisation
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; This is an outline-style {{visualisation}} similar to that found in many operating system file-system views. A similar visualisation can be used for other forms of {{hierarchical data}}.
        )

    [fine positioning tasks] =&gt; Array
        (
            [slug] =&gt; fine positioning tasks
            [parent] =&gt; 
            [name] =&gt; fine positioning tasks
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; A task requiring fine motor skills and direct gaze, for example selecting a small target with an on-screen pointer.
        )

    [fitts' law] =&gt; Array
        (
            [slug] =&gt; fitts' law
            [parent] =&gt; 
            [name] =&gt; Fitts' Law
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; {{Paul Fitts}} found that, for simple pointing tasks, {{task completion time}} is proportional to the {{Index of Difficulty (IoD)}}, which is essentially the logarithm of the distance to target divided by the target size: IoD = log2 ( distance to target/target size ). While Fitts' original research was on physical one-dimensional pointing alternating between two metal strips, Fitts&rsquo; Law has been found to hold for many kinds of pointing tasks, with a wide variety of devices, over multiple orders of magnitude. Although Fitts&rsquo; Law holds in many situations it is not universal; crucially it depends on situations where there is {{hand&ndash;eye coordination}} and where movement error is proportional to distance moved. 
        )

    [five users] =&gt; Array
        (
            [slug] =&gt; five users
            [parent] =&gt; 
            [name] =&gt; five users (the myth)
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; Often it is said that five users are enough for {{usability testing}}. This had some truth in the particular original context of {{iterative software development}}, where only enough issues needed to be uncovered for the next cycle of re-development. However, it is certainly not sufficient for statistical purposes.
        )

    [five users are enough] =&gt; Array
        (
            [slug] =&gt; five users are enough
            [parent] =&gt; 
            [name] =&gt; five users are enough
            [canonical] =&gt; five users
            [see] =&gt; 
            [description] =&gt; 
        )

    [font size] =&gt; Array
        (
            [slug] =&gt; font size
            [parent] =&gt; 
            [name] =&gt; font size
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; The size of characters in a {{font}} is usually measured in points, where a printer's point is 1/72 of an inch. So the tall characters in a &lt;span style=&quot;font-size:12pt&quot;&gt;12pt font&lt;/span&gt; are around 1/6 of an inch high, whereas a &lt;span style=&quot;font-size:14pt&quot;&gt;14pt font&lt;/span&gt; is about 1/5 of an inch and &lt;span style=&quot;font-size:7pt&quot;&gt;7pt font&lt;/span&gt; is about 1/10 of an inch. However, the exact size does vary between fonts. On screen the physical size of pixels (the {{screen resolution}}) varies. Old displays often used to have around 70 pixels per inch, so a point and a pixel were nearly the same, but now that varies a lot more, particularly for phone displays and retina displays. The device tries to choose a pixel-height that closely matches the paper dimensions of the desired font. If the precise screen size of characters matters, the font size may be measured in pixels.
        )

    [font sizes] =&gt; Array
        (
            [slug] =&gt; font sizes
            [parent] =&gt; 
            [name] =&gt; font sizes
            [canonical] =&gt; font size
            [see] =&gt; 
            [description] =&gt; 
        )

    [formative assessment] =&gt; Array
        (
            [slug] =&gt; formative assessment
            [parent] =&gt; 
            [name] =&gt; formative assessment
            [canonical] =&gt; formative evaluation
            [see] =&gt; 
            [description] =&gt; 
        )

    [formative evaluation] =&gt; Array
        (
            [slug] =&gt; formative evaluation
            [parent] =&gt; 
            [name] =&gt; formative evaluation
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; Focused on making the system better, formative evaluation is performed on the design artefacts (sketch, prototype, or experimental system) during the cycles of design&ndash;build&ndash;
test. Its form varies from {{expert evaluation}} to large-scale {{user testing}}, and its primary purpose is to uncover usability or experience problems for the next cycle. Contrast with {{summative evaluation}}.
        )

    [formative evaluations] =&gt; Array
        (
            [slug] =&gt; formative evaluations
            [parent] =&gt; 
            [name] =&gt; formative evaluations
            [canonical] =&gt; formative evaluation
            [see] =&gt; 
            [description] =&gt; 
        )

    [hawthorne effect] =&gt; Array
        (
            [slug] =&gt; hawthorne effect
            [parent] =&gt; 
            [name] =&gt; Hawthorne effect
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; This when subjects in a study or experiment behave differently because they know they are being observed.  For example in an educational or work setting, subjects may pay more attention to a task when they know they are being watched and recorded.  This may simply life or depress oerall performace, but is particlarly problematic when it casues {{bias}}, in particular, if subjects are aware that the pwerson organising the study or observing the study has an interest in a particular outcome.  In {{user studies}} this often occurs when new software is being trialed.  Subjects may try harder at the favoured system, or give better subjcetive assessments, just to be nice.
        )

    [hci] =&gt; Array
        (
            [slug] =&gt; hci
            [parent] =&gt; 
            [name] =&gt; HCI
            [canonical] =&gt; 
            [see] =&gt; human-computer interaction
            [description] =&gt; 
        )

    [hci studies] =&gt; Array
        (
            [slug] =&gt; hci studies
            [parent] =&gt; 
            [name] =&gt; HCI studies
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; Research in {{HCI}} often involves some form of study with people: sometimes using a {{prototype}}, sometimes in some form of {{focus group}} or {{interview}}, sometimes in a more experimental situation closer to pure psychology. The methods used are often similar to the {{user studies}} or {{user experience studies}} used by {{usability practitioners}} during {{user interface development}}, but the aims are different.
        )

    [human-computer interaction] =&gt; Array
        (
            [slug] =&gt; human-computer interaction
            [parent] =&gt; 
            [name] =&gt; Human&amp;ndash;Computer Interaction
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; This is the discipline focused on understanding of the way people use and are impacted by computer technology and the way that technology can be designed to better serve human needs. This includes single users interacting directly with devices, but also the impact of computers at the level of work groups, families, organisations and communities.
        )

    [image recognition] =&gt; Array
        (
            [slug] =&gt; image recognition
            [parent] =&gt; 
            [name] =&gt; image recognition
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; Software that uses algorithms to interpret image data, either static pictures or video. For example, it might be used to recognise faces in a picture so that they can be more easily labelled, or to recognise hand gestures using the computer's camera. Before {{GPS}} was common in phones, some applications would match the image on the phone with known landmarks to enable  location-specific services such as historical information or geo annotation. Similar techniques are also common in {{augmented reality}} systems that overlay digital imagery over a live feed of the real world. The accuracy of the image recognition can affect the {{user experience}}.
        )

    [in the wild] =&gt; Array
        (
            [slug] =&gt; in the wild
            [parent] =&gt; 
            [name] =&gt; in the wild
            [canonical] =&gt; in-the-wild
            [see] =&gt; 
            [description] =&gt; 
        )

    [in-the-wild] =&gt; Array
        (
            [slug] =&gt; in-the-wild
            [parent] =&gt; 
            [name] =&gt; in-the-wild
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; An {{ethnographic study}} is carried out in the normal context of the subjects of the study, for example observing people in their own workplace. It is a form of {{in the wild}} study; these have high {{ecological validity}} but hold their own specific challenges, such as {{replication}} and control of {{variability}}.
        )

    [in-the-wild studies] =&gt; Array
        (
            [slug] =&gt; in-the-wild studies
            [parent] =&gt; 
            [name] =&gt; in-the-wild studies
            [canonical] =&gt; in-the-wild
            [see] =&gt; 
            [description] =&gt; 
        )

    [index of difficulty] =&gt; Array
        (
            [slug] =&gt; index of difficulty
            [parent] =&gt; 
            [name] =&gt; index of difficulty (IoD)
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; The logarithm of the distance to target divided by the target size: IoD = log&lt;sub&gt;2&lt;/sub&gt; ( distance to target/target size ). Used in {{Fitts' Law}}.
        )

    [index of difficulty (iod)] =&gt; Array
        (
            [slug] =&gt; index of difficulty (iod)
            [parent] =&gt; 
            [name] =&gt; index of difficulty (iod)
            [canonical] =&gt; index of difficulty
            [see] =&gt; 
            [description] =&gt; 
        )

    [individual differences] =&gt; Array
        (
            [slug] =&gt; individual differences
            [parent] =&gt; 
            [name] =&gt; individual differences
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; Differences between subjects that may influence the effect being studied. For some studies these individual differences can mask the thing being examined (create {{noise}}). Ways to reduce the impact of individual differences in such situations include using a very {{narrow user group}}, having the same users perform on different systems (a {{within-subjects design}}), and choosing participants of the same age and experience to {{reduce noise}}. Each of these has implications for the {{validity}} of results. Within {{interaction design}} and {{user experience design}} it is crucial to remember that people are different. Sometimes you have to create a 'one size fits all' application, but if you can understand differences between users this can lead to better designs, whether different applications targeted at different user groups, {{customisation}} options within a single application, or {{intelligent interfaces}} that adapt themselves to the user.
        )

    [intelligent interface] =&gt; Array
        (
            [slug] =&gt; intelligent interface
            [parent] =&gt; 
            [name] =&gt; intelligent interface
            [canonical] =&gt; intelligent interfaces
            [see] =&gt; 
            [description] =&gt; 
        )

    [intelligent interfaces] =&gt; Array
        (
            [slug] =&gt; intelligent interfaces
            [parent] =&gt; 
            [name] =&gt; intelligent interfaces
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; These are systems that use some form of {{artificial intelligence}} or {{machine learning}} as part of {{user interaction}}. Many of us will see examples of this daily as web sites adapt content and especially adverts according to models based on our past behaviour. More advanced systems might try to help us to complete tasks or maybe automate repeated tasks based on examples.
        )

    [iod] =&gt; Array
        (
            [slug] =&gt; iod
            [parent] =&gt; 
            [name] =&gt; iod
            [canonical] =&gt; index of difficulty (iod)
            [see] =&gt; 
            [description] =&gt; 
        )

    [iterative development] =&gt; Array
        (
            [slug] =&gt; iterative development
            [parent] =&gt; 
            [name] =&gt; iterative development
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; A software design cycle that includes repeated stages of evaluation of evolving designs, prototypes or systems. The two main kinds of evaluation are {{formative evaluation}} at each stage to improve the design and {{summative evaluation}} at the end to assess whether the final design is sufficiently good.
        )

    [iterative evaluation] =&gt; Array
        (
            [slug] =&gt; iterative evaluation
            [parent] =&gt; 
            [name] =&gt; iterative evaluation
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; The {{formative evaluation}} in {{iterative development}}
        )

    [iterative software development] =&gt; Array
        (
            [slug] =&gt; iterative software development
            [parent] =&gt; 
            [name] =&gt; iterative software development
            [canonical] =&gt; iterative development
            [see] =&gt; 
            [description] =&gt; 
        )

    [learning effects] =&gt; Array
        (
            [slug] =&gt; learning effects
            [parent] =&gt; 
            [name] =&gt; learning effects
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; A type of {{order effect}} where a user is better at a second test because they have already got used to the general ideas of an application in the first test. 
        )

    [likert scale] =&gt; Array
        (
            [slug] =&gt; likert scale
            [parent] =&gt; 
            [name] =&gt; Likert scale
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; A scale to measure degrees of agreement or satisfaction. The values are often coded as numbers and there is an order but otherwise no specific meaning to the values. This is {{ordinal data}}. &lt;br&gt; An example of survey question using a Likert scale might be:&lt;br&gt; The top level menu items were:  unintelligible &ndash; 1 &ndash; 2 &ndash; 3 &ndash; 4 &ndash; 5 &ndash; always easy to interpret.
        )

    [matched users] =&gt; Array
        (
            [slug] =&gt; matched users
            [parent] =&gt; 
            [name] =&gt; matched users
            [canonical] =&gt; matching subjects
            [see] =&gt; 
            [description] =&gt; 
        )

    [matching subjects] =&gt; Array
        (
            [slug] =&gt; matching subjects
            [parent] =&gt; 
            [name] =&gt; matching subjects
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; When the same subject repeats a test under different conditions (e.g. evaluating two systems) there may be {{learning effects}}. One way around this is to have different subjects for each condition, but to have two or more subjects who are very similar (in gender, age, skills), and to allocate one from each pair (or matched group) to each condition. Matching subjects makes results more robust, requiring fewer assumptions, but typically has less {{statistical power}} than a {{within-subjects experiment}}.
        )

    [menu navigation] =&gt; Array
        (
            [slug] =&gt; menu navigation
            [parent] =&gt; 
            [name] =&gt; menu navigation
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; Using menus as an interaction mechanism to find one's way around a system.
        )

    [menu selection] =&gt; Array
        (
            [slug] =&gt; menu selection
            [parent] =&gt; 
            [name] =&gt; menu selection
            [canonical] =&gt; menu navigation
            [see] =&gt; 
            [description] =&gt; 
        )

    [modal dialog] =&gt; Array
        (
            [slug] =&gt; modal dialog
            [parent] =&gt; 
            [name] =&gt; modal dialog
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; A modal dialog prevents other forms of user interaction while it is showing.  This is suitable for situations where it would be inappropriate for the user to do other interactions, for example where there has been some sort of event (such as a network failure) that requires immediate attention, or some action, such as 'save file' that should be completed before continuing.    This is in contrast to a {{non-modal dialog}}.
        )

    [muller-lyer illusion] =&gt; Array
        (
            [slug] =&gt; muller-lyer illusion
            [parent] =&gt; 
            [name] =&gt; M&amp;uuml;ller&amp;ndash;Lyer illusion
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; A well-known optical illusion: there are two horizontal parallel lines of equal length, the top one bounded by outward-facing arrows and the lower one by inward-facing arrows. The lower line looks longer, though it is the same length. The illusion was described by Franz Carl M&uuml;ller-Lyer, a German sociologist, in 1889.
        )

    [non-modal dialog] =&gt; Array
        (
            [slug] =&gt; non-modal dialog
            [parent] =&gt; 
            [name] =&gt; non-modal dialog
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; A non-modal dialog allows other forms of user interaction while it is showing.  This is suitable for tool palettes, or helpful suggestions such as intelligent help or spelling corrections.  This is in contrast to a {{modal dialog}}.
        )

    [peripheral vision] =&gt; Array
        (
            [slug] =&gt; peripheral vision
            [parent] =&gt; 
            [name] =&gt; peripheral vision
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; Where a person is not looking directly at something, but it is still visible out of their central vision. Human peripheral vision is not accurate enough for fine {{positioning tasks}}.
        )

    [pietree] =&gt; Array
        (
            [slug] =&gt; pietree
            [parent] =&gt; 
            [name] =&gt; pietree
            [canonical] =&gt; pietree visualisation
            [see] =&gt; 
            [description] =&gt; 
        )

    [pietree visualisation] =&gt; Array
        (
            [slug] =&gt; pietree visualisation
            [parent] =&gt; 
            [name] =&gt; PieTree
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; The PieTree is an interactive {{constant area visualisation}} for hierarchical data with some form of numerical attribute including values at the nodes &ndash; for example in a website where there are visits to both the main page of a section and also to sub-pages. The visualisation starts off like a standard pie chart where each segment represents a branch of the tree (e.g. section of the site), except there is also a small circle in the middle representing the value at the root (e.g home page). If any of the segments is selected it breaks into smaller segments for each sub-branch, and so on. 
        )

    [pointing task] =&gt; Array
        (
            [slug] =&gt; pointing task
            [parent] =&gt; 
            [name] =&gt; pointing task
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; A class of low-level device interaction task where a mouse, trackpad, stylus or finger is used  to move towards a target or follow some sort of path. This is typically to target an element onscreen in order to act on it, for example to drag it or select it. The time for positioning tasks often satisfies some variant of {{Fitts' Law}}. 
        )

    [pointing tasks] =&gt; Array
        (
            [slug] =&gt; pointing tasks
            [parent] =&gt; 
            [name] =&gt; pointing tasks
            [canonical] =&gt; pointing task
            [see] =&gt; 
            [description] =&gt; 
        )

    [pre-register] =&gt; Array
        (
            [slug] =&gt; pre-register
            [parent] =&gt; 
            [name] =&gt; pre-register
            [canonical] =&gt; pre-registration
            [see] =&gt; 
            [description] =&gt; 
        )

    [pre-registration] =&gt; Array
        (
            [slug] =&gt; pre-registration
            [parent] =&gt; 
            [name] =&gt; pre-registration
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; A way to avoid the {{file drawer effect}} by recording a statement before starting an experiment to specify the hypothesis being tested and which statistical technique will be used. This forces justification of the reasons for any {{post-hoc hypothesis}}. It is standard practice in many areas of science, and becoming so in {{HCI}}.
        )

    [public domain] =&gt; Array
        (
            [slug] =&gt; public domain
            [parent] =&gt; 
            [name] =&gt; public domain
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; This is when the various materials used or produced in research are made available to everyone in some publicly accessible form. These materials include instructions, software (if applicable), and of course the raw study data, whether this is survey reports, video, or keystroke logging, as well as derived data, all the way to the data that lies behind the graphs in your published papers.
        )

    [publication bias] =&gt; Array
        (
            [slug] =&gt; publication bias
            [parent] =&gt; 
            [name] =&gt; publication bias
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; If only {{positive results}} are publshied, then it may appaer that they are more {{significant}} (in all senses of the word) than they really are.  This is becasue of you do enough experiments or studies, then by raodm chance one of them will come up 5% significant about 1 time in 20. Publication bias occurs artly because researchers self-select to report things that are most impressive, but also because journal and conference reviewers may not accept papers with {{negative results}}. In {{qualitative}} studies, there can be similar effects, if you look at enough people, or enough events you will see some interesting things, and may tend to report these leaing to a sense that they are common, whereas they may not be at all typical.
        )

    [publish or perish] =&gt; Array
        (
            [slug] =&gt; publish or perish
            [parent] =&gt; 
            [name] =&gt; publish or perish
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; A cultural definition of academic success that requires peer-reviewed publication of research results.
        )

    [qualitative methods] =&gt; Array
        (
            [slug] =&gt; qualitative methods
            [parent] =&gt; 
            [name] =&gt; qualitative methods
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; Research methods such as rich observations, ethnography, or post-experiment interviews, which are suited to exploratory research, revealing the processes and mechanisms by which something occurs and answering how and why questions. Contrast with {{quantitative methods}}.
        )

    [qualitative research] =&gt; Array
        (
            [slug] =&gt; qualitative research
            [parent] =&gt; 
            [name] =&gt; qualitative research
            [canonical] =&gt; qualitative methods
            [see] =&gt; 
            [description] =&gt; 
        )

    [quantitative methods] =&gt; Array
        (
            [slug] =&gt; quantitative methods
            [parent] =&gt; 
            [name] =&gt; quantitative methods
            [canonical] =&gt; quantitative data
            [see] =&gt; 
            [description] =&gt; 
        )

    [quantitative data] =&gt; Array
        (
            [slug] =&gt; quantitative data
            [parent] =&gt; 
            [name] =&gt; quantitative data
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; Any data based on numbers or measurable values. This may include objectively measurable values such as {{task completion times}} or more subjective data such as {{opinion polls}}. Contrast with {{qualitative methods}}.
        )

    [replichi] =&gt; Array
        (
            [slug] =&gt; replichi
            [parent] =&gt; 
            [name] =&gt; RepliCHI
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; An initiative of ACM CHI to increase {{repeatability}}, which led to the addition of a &ldquo;validation and refutation&rdquo; category in some subsequent conferences, and to long-term changes in the ACM {{CHI Conference}} publication guidelines.
        )

    [representative] =&gt; Array
        (
            [slug] =&gt; representative
            [parent] =&gt; 
            [name] =&gt; representative
            [canonical] =&gt; representative sample
            [see] =&gt; 
            [description] =&gt; 
        )

    [representative sample] =&gt; Array
        (
            [slug] =&gt; representative sample
            [parent] =&gt; 
            [name] =&gt; representative sample
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; A small group who exhibit the typical characteristics of a larger group. Results from the study of a representative sample can be extrapolated to the larger group. Sometimes this sample may be chosen randomly, or may be deliberately chosen so as to ensure that important features such as gender, age or experience match those of the relevant {{population}} as a whole.
        )

    [response time] =&gt; Array
        (
            [slug] =&gt; response time
            [parent] =&gt; 
            [name] =&gt; response time
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; The time it takes for someone to respond to some sort of event, notification, alarm or cue. This may be affected by the form in which the event is presented (e.g. a loud sound vs a subtle change at the edge of the screen), and by the cognitive state of the user (e.g. waiting attentively or highly focused on another task). In the case when some sort of decision is also needed, then other issues will also be important, such as the number of choices and preparedness or implicit biases of the user.
        )

    [response times] =&gt; Array
        (
            [slug] =&gt; response times
            [parent] =&gt; 
            [name] =&gt; response times
            [canonical] =&gt; response time
            [see] =&gt; 
            [description] =&gt; 
        )

    [restricted device] =&gt; Array
        (
            [slug] =&gt; restricted device
            [parent] =&gt; 
            [name] =&gt; restricted device
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; A method to {{reduce noise}} by limiting the functionality of a device; for example, locking a mobile phone so that it can only use the test app, thereby ensuring that activity is directed toward the aspects being studied.
        )

    [restricted system] =&gt; Array
        (
            [slug] =&gt; restricted system
            [parent] =&gt; 
            [name] =&gt; restricted system
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; A method to {{reduce noise}} by limiting the functionality of a system. For example, in a social media application you might disable everything apart from music-related features if these are the focus of your study.
        )

    [restricted tasks] =&gt; Array
        (
            [slug] =&gt; restricted tasks
            [parent] =&gt; 
            [name] =&gt; restricted tasks
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; A method to {{reduce noise}} by limiting the activity of participants, while still maintaining a level of {{ecological validity}}; for example, giving them a scripted task to perform, but within their normal environment.
        )

    [selection bias] =&gt; Array
        (
            [slug] =&gt; selection bias
            [parent] =&gt; 
            [name] =&gt; selection bias
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; This is when the way the people who are considered in a study uninitentionally includes some kinds of people more than others and thus induces a {{bias}} in the way resuts are interpretted.  This may occur due to {{sampling bias}} in the way people are initially selected, or other effects such as {{self-selection}} of participants in study, or participants dropping out.  Note that this affects both {{qualitative}} and {{quantitative}} analysis.
        )

    [snowball sample] =&gt; Array
        (
            [slug] =&gt; snowball sample
            [parent] =&gt; 
            [name] =&gt; snowball sample
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; An initial set of contacts is used as the first set of subjects, and they are then asked to suggest any of their own contacts who might take part in the survey. A danger of this approach is that there may be {{internal non-independence}} if the contacts of each individual are likely to share the feature or ability being investigated &ndash; for example contacts may well share political views, or educational background.
        )

    [snowball samples] =&gt; Array
        (
            [slug] =&gt; snowball samples
            [parent] =&gt; 
            [name] =&gt; snowball samples
            [canonical] =&gt; snowball sample
            [see] =&gt; 
            [description] =&gt; 
        )

    [social network connection data] =&gt; Array
        (
            [slug] =&gt; social network connection data
            [parent] =&gt; 
            [name] =&gt; social network connection data
            [canonical] =&gt; social network data
            [see] =&gt; 
            [description] =&gt; 
        )

    [social network data] =&gt; Array
        (
            [slug] =&gt; social network data
            [parent] =&gt; 
            [name] =&gt; social network data
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; Data arising from social networks, such as the number of friends or contacts. Often social network data follows a {{power-law distribution}} and so {{statistical tests}} designed for {{approximately Normal}} data &lt;em&gt;cannot&lt;/em&gt; be used.
        )

    [social networks] =&gt; Array
        (
            [slug] =&gt; social networks
            [parent] =&gt; 
            [name] =&gt; social networks
            [canonical] =&gt; social network data
            [see] =&gt; 
            [description] =&gt; 
        )

    [software design] =&gt; Array
        (
            [slug] =&gt; software design
            [parent] =&gt; 
            [name] =&gt; software design
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; Software design involves many aspects, for example the choice of internal protocols between front-end and back-end services; however, from an HCI point of view, the crucial aspects are those relating to the {{user interface}}, {{user experience}} and the way in which it fits into broader {{socio-technical systems}}.
        )

    [software development] =&gt; Array
        (
            [slug] =&gt; software development
            [parent] =&gt; 
            [name] =&gt; software development
            [canonical] =&gt; software development process
            [see] =&gt; 
            [description] =&gt; 
        )

    [software development process] =&gt; Array
        (
            [slug] =&gt; software development process
            [parent] =&gt; 
            [name] =&gt; software development process
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; There are many processes by which software is designed and created that relate to the kind of software, application domain and organisation, but those parts that involve any form of interaction with the user typically follow an {{iterative process}}. Initial design activity leads to the making of a demonstrable artefact: from storyboards and sketches to wireframes, hi-res prototypes or a running system. The artefact is subjected to testing or evaluation: {{formative evaluation}} in the early stages and {{summative evaluation}} on a pre-release product.
        )

    [sonic enhancement] =&gt; Array
        (
            [slug] =&gt; sonic enhancement
            [parent] =&gt; 
            [name] =&gt; sonic enhancement
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; A way to make clicking an onscreen button more evident by adding sound to simulate a physical effect. More generally, many aspects of an interface can be enhanced by additional audio feedback, such as the crunching paper sound that some systems use when a file is thrown into the (desktop) trash bin. While sometimes provided for aesthetic reasons, this may also add feedback.
        )

    [steering task] =&gt; Array
        (
            [slug] =&gt; steering task
            [parent] =&gt; 
            [name] =&gt; steering task
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; This can refer to literal steering of a tractor or car (or simulation of these), or may refer to a form of {{pointing tasks}} where the pointer has to be navigated along a path. In the former case, the steering may be used as a {{distractor task}} for another {{primary task}} that is the real purpose of an experiment.
        )

    [stemming] =&gt; Array
        (
            [slug] =&gt; stemming
            [parent] =&gt; 
            [name] =&gt; stemming
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; Stemming is the reducing of words to their root.  For example, removing the 'ing' from stemming to get 'stem'.  However, even this example shows it is not simple.  The root of 'stemming' is 'stem' not 'stemm'!
&lt;br&gt;
Stemming is used in many free text information retrieval systems to improve the matching algorithms. 
&lt;br&gt;
The &lt;a href=&quot;https://hcibook.com/e3/search/l&quot;&gt;full text search&lt;/a&gt; of &lt;a href=&quot;https://hcibook.com/e3/&quot;&gt;Human-Computer Interaction&lt;/a&gt; uses the most rudimentary stemming - it removes 's' from the ends of words.
There are a small number of 'stop words' which are not stemmed to prevent it from stemming words such as 'fuss', but that is all.
&lt;br&gt;
If you are intersted in more complex forms of stemming, see the (Internet Archive) pages for  the &lt;a href=&quot;https://web.archive.org/web/20060819173645/http://www.comp.lancs.ac.uk/computing/research/stemming/Links/implementations.htm&quot;&gt;Lancaster (Paice/Husk) stemming algorithm&lt;/a&gt; and more recent &lt;a href=&quot;https://github.com/words/lancaster-stemmer&quot;&gt;JavaScript implementation&lt;/a&gt; of it on GitHub.
        )

    [subconscious reactions] =&gt; Array
        (
            [slug] =&gt; subconscious reactions
            [parent] =&gt; 
            [name] =&gt; subconscious reactions
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; One of two systems of thought identified in psychology: subconscious and conscious, sometimes also called System 1 and System 2 respectively. Subconscious reactions are based on semi probabilistic associations built up through experience. Sometimes subconscious reactions lead to an immediate action, such as jumping out of the way if we hear the sound of an approaching car; at other times they are more about a feeling or gut reaction &ndash; we are aware of the reaction, but not the reasons for it. Contrast with {{conscious thinking}}.
        )

    [subjects] =&gt; Array
        (
            [slug] =&gt; subjects
            [parent] =&gt; 
            [name] =&gt; subjects
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; The humans involved in a study. Because the term may sound rather clinical or instrumental, some researchers prefer the terms &lsquo;user&rsquo;, or &lsquo;participant&rsquo; if there is a richer engagement. Both these alternatives have their own connotations, and 'subject' remains the most commonly used in statistics.
        )

    [summative evaluation] =&gt; Array
        (
            [slug] =&gt; summative evaluation
            [parent] =&gt; 
            [name] =&gt; summative evaluation
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; Focused on checking that the system works and is good enough, summative evaluation is performed at the end of the {{software development process}} on a pre-release product. It may be related to contractual obligations (whether the system meets agreed specifications) or may compare the system with others. Less formally, summative evaluation may simply be an assessment that enough work has been done based on the cumulative evidence from earlier stages. Contrast with {{formative evaluation}}.
        )

    [summative evaluations] =&gt; Array
        (
            [slug] =&gt; summative evaluations
            [parent] =&gt; 
            [name] =&gt; summative evaluations
            [canonical] =&gt; summative evaluation
            [see] =&gt; 
            [description] =&gt; 
        )

    [survey data] =&gt; Array
        (
            [slug] =&gt; survey data
            [parent] =&gt; 
            [name] =&gt; survey data
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; Data obtained by asking people questions, often utilising an electronic or paper form or through guided interviews. The volume of survey data can often be far higher than is provided by more intensive methods such as {{direct observation}}, {{usability tests}} or more in depth interviews. Closed questions, whose answers are chosen from a fixed set of options, are useful as they generate easy to analyse statistical data, but they often only tell you &lt;em&gt;what&lt;/em&gt; is happening. Typically you need more {{qualitative data}} to help you understand &lt;em&gt;why&lt;/em&gt; and &lt;em&gt;how&lt;/em&gt;, including the {{motivation}} and {{mechanism}}. Such data may be obtained through {{open questions}} in the survey, or through complementary methods.
        )

    [target size] =&gt; Array
        (
            [slug] =&gt; target size
            [parent] =&gt; 
            [name] =&gt; target size
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; In a {{pointing task}} this is the size of the area you want to point at, such as a button or icon. It is used in {{Fitts' Law}} to predict the time it takes to locate the target.
        )

    [targeted tasks] =&gt; Array
        (
            [slug] =&gt; targeted tasks
            [parent] =&gt; 
            [name] =&gt; targeted tasks
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; Tasks designed to deliberately  expose the effects of an intervention by focusing on the aspects of the system that are being tested, minimising interaction with other elements. For example, if you have added a feature to help users keep track of what they are doing, a {{targeted task}} could include a lot of interruptions. Targeted tasks increase {{effect}} in the {{noise-effect-number triangle}} and so increase {{statistical power}}. However, targeting can be misleading if you are not careful, as the {{targeted task}} may not be representative of the full range of tasks that are likely to be carried out; that is {{generalisation}} can be difficult.
        )

    [targeted user] =&gt; Array
        (
            [slug] =&gt; targeted user
            [parent] =&gt; 
            [name] =&gt; targeted user
            [canonical] =&gt; targeted user group
            [see] =&gt; 
            [description] =&gt; 
        )

    [targeted user group] =&gt; Array
        (
            [slug] =&gt; targeted user group
            [parent] =&gt; 
            [name] =&gt; targeted user group
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; A group for whom we believe we will see the maximum effect is deliberately chosen. For example, a new menu system would be tested more effectively for short-term memory requirements on an elderly user group who are more likely to have some short-term memory loss, rather than on a younger user group. Targeted user groups increase {{effect}} in the {{noise-effect-number triangle}} and so increase {{statistical power}}. However, targeting can be misleading if you are not careful as the {{targeted user group}} may not be representative of the full range of users who are likely to use the system, therefore {{generalisation}} can be difficult.
        )

    [targeted user groups] =&gt; Array
        (
            [slug] =&gt; targeted user groups
            [parent] =&gt; 
            [name] =&gt; targeted user groups
            [canonical] =&gt; targeted user group
            [see] =&gt; 
            [description] =&gt; 
        )

    [task completion time] =&gt; Array
        (
            [slug] =&gt; task completion time
            [parent] =&gt; 
            [name] =&gt; task completion time
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; The time taken to complete a specified task is often used as a measure when comparing two systems. This may be a high-level task, such as finding a product on an online shopping site; or a low-level task, such as a {{pointing task}} modelled by  {{Fitts' Law}}. 
        )

    [task completion times] =&gt; Array
        (
            [slug] =&gt; task completion times
            [parent] =&gt; 
            [name] =&gt; task completion times
            [canonical] =&gt; task completion time
            [see] =&gt; 
            [description] =&gt; 
        )

    [tasks] =&gt; Array
        (
            [slug] =&gt; tasks
            [parent] =&gt; 
            [name] =&gt; tasks
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; Experimental or study tasks are the actions that users are specifically asked to perform. Measurements such as {{task completion time}} can be observed and recorded. Tasks can be manipulated to gain {{statistical power}} using the {{noise-effect-number triangle}}.
        )

    [temporal data] =&gt; Array
        (
            [slug] =&gt; temporal data
            [parent] =&gt; 
            [name] =&gt; temporal data
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; Data recorded over a period of time, where the time at which events occur is a critical part of the data. This can include very long-term phenomena such as the level of usage of a web site, shorter term such as the trace of user interactions while performing a task, or very fine scale such as some biological measurements. There are special statistical techniques for modelling {{time series}} data.
        )

    [treemap] =&gt; Array
        (
            [slug] =&gt; treemap
            [parent] =&gt; 
            [name] =&gt; TreeMap
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; The TreeMap is a {{constant area visualisation}} invented by Ben Shneiderman for hierarchical data with some form of numerical attribute, for example the sizes of files and folders on a computer disk. The most basic form starts with a rectangular area and then recursively divides the area alternatively horizontally using the total values for each level.
        )

    [usability evaluation] =&gt; Array
        (
            [slug] =&gt; usability evaluation
            [parent] =&gt; 
            [name] =&gt; usability evaluation
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; This is about evaluating how usable a system is; the term can be read quite broadly, or may be distinguished from evaluating {{user experience}}.There are many ways of evaluating usability: {{expert evaluation}} techniques are useful for early design or when users are difficult to contact, but typically the gold standard is expected to use real users. When evaluating with real users there are still many options from {{controlled laboratory experiments}} to {{in the wild}} studies.
        )

    [user experience] =&gt; Array
        (
            [slug] =&gt; user experience
            [parent] =&gt; 
            [name] =&gt; user experience
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; Aspects of a system that affect the user's emotional state; that is creating a (usually) positive experience of using the system.
        )

    [user experience design] =&gt; Array
        (
            [slug] =&gt; user experience design
            [parent] =&gt; 
            [name] =&gt; user experience design
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; This refers to the parts of the design process and the methods used to ensure a desired {{user experience}}.
        )

    [user experience studies] =&gt; Array
        (
            [slug] =&gt; user experience studies
            [parent] =&gt; 
            [name] =&gt; user experience studies
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; These are studies that attempt to {{evaluate}} or otherwise understand the {{user experience}} of a study. It is possible to measure {{objective}} aspects such as heart rate, but the emotional and personal nature of {{user experience}} mean that more {{qualitative methods}} are often used, or various forms of subjective questionnaire. 
        )

    [user experience testing] =&gt; Array
        (
            [slug] =&gt; user experience testing
            [parent] =&gt; 
            [name] =&gt; user experience testing
            [canonical] =&gt; user experience studies
            [see] =&gt; 
            [description] =&gt; 
        )

    [user interface] =&gt; Array
        (
            [slug] =&gt; user interface
            [parent] =&gt; 
            [name] =&gt; user interface
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; The part of a system that the user interacts with. Typically this is some form of screen-based interface with buttons, menus, etc., such as an app or desktop graphical user interface. However, interaction may be through alternatives such as speech, gesture or physical things in the environment that are sensed by the computer.
        )

    [user interface development] =&gt; Array
        (
            [slug] =&gt; user interface development
            [parent] =&gt; 
            [name] =&gt; user interface development
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; The process of creating the user-facing aspects of a system, from initial scoping and design through to coding and deployment. Typically {{iterative development}} is used where there are cycles where some form of {{prototype}} or {{design sketch}} is evaluated in a {{user study}} or {{expert evaluation}}. The design is then altered in the light of the {{formative evaluation}}, leading into another cycle.
        )

    [user interface properties] =&gt; Array
        (
            [slug] =&gt; user interface properties
            [parent] =&gt; 
            [name] =&gt; user interface properties
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; This usually refers to specific generic properties that influence the {{usability}} or {{user experience}} of a system in some way. For example, it is usually the case that interactions are more easily learnt if the interface is {{consistent}}. A {{user interface property}} can be a form of {{generative artefact}} when one deliberately tries to create a system that adheres to the principle, and as such can be hard to {{evaluate}}.
        )

    [user interface testing] =&gt; Array
        (
            [slug] =&gt; user interface testing
            [parent] =&gt; 
            [name] =&gt; user interface testing
            [canonical] =&gt; 
            [see] =&gt; usability evaluation
            [description] =&gt; 
        )

    [user studies] =&gt; Array
        (
            [slug] =&gt; user studies
            [parent] =&gt; 
            [name] =&gt; user studies
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; When a system or context is investigated by using real users. {{User studies}} are often regarded as being the gold standard form of {{evaluation}}, but may not always be possible, for example, if the intended users are difficult to contact or a vulnerable group. 
        )

    [user study] =&gt; Array
        (
            [slug] =&gt; user study
            [parent] =&gt; 
            [name] =&gt; user study
            [canonical] =&gt; user studies
            [see] =&gt; 
            [description] =&gt; 
        )

    [user test] =&gt; Array
        (
            [slug] =&gt; user test
            [parent] =&gt; 
            [name] =&gt; user test
            [canonical] =&gt; user studies
            [see] =&gt; 
            [description] =&gt; 
        )

    [user testing] =&gt; Array
        (
            [slug] =&gt; user testing
            [parent] =&gt; 
            [name] =&gt; user testing
            [canonical] =&gt; user studies
            [see] =&gt; 
            [description] =&gt; 
        )

    [user trial] =&gt; Array
        (
            [slug] =&gt; user trial
            [parent] =&gt; 
            [name] =&gt; user trial
            [canonical] =&gt; user studies
            [see] =&gt; 
            [description] =&gt; 
        )

    [user-testing] =&gt; Array
        (
            [slug] =&gt; user-testing
            [parent] =&gt; 
            [name] =&gt; user-testing
            [canonical] =&gt; user studies
            [see] =&gt; 
            [description] =&gt; 
        )

    [validation] =&gt; Array
        (
            [slug] =&gt; validation
            [parent] =&gt; 
            [name] =&gt; validation
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; The general process of establishing whether something (an interaction technique, system, theory, design principle, toolkit) is in some sense 'valid' &ndash; correct, true, usable. Within HCI there is often a focus on {{empirical evaluation}} of a system, theory or other artefact after it has been created. However, this is effectively impossible for {{generative artefacts}} (things that create other things) such as toolkits, methodologies or design principles, and then other methods, such as {{justification}} based on reasoning and past literature, become more important.
        )

    [visualisation] =&gt; Array
        (
            [slug] =&gt; visualisation
            [parent] =&gt; 
            [name] =&gt; visualisation
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; Methods and systems to make it easier to see trends or other patterns in data or derived results. This varies from simple {{scatter plots}} to more complex information visualisations such as the {{TreeMap}} or {{parallel coordinates}}. Where {{visualisation}} is combined with machine learning or other advanced data analysis techniques, it is referred to as {{visual analytics}}. Despite the 'visual' word in its name, {{visualisation}} is also sometimes used to refer to ways to communicate information through other senses such as auditory versions of graphs.
        )

    [weird people] =&gt; Array
        (
            [slug] =&gt; weird people
            [parent] =&gt; 
            [name] =&gt; WEIRD people
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; Western, Educated, Industrialized, Rich, and Democratic &ndash; Henrich et al. pointed out that the vast majority of psychological studies use a very specific type of subject, not at all typical of the global population. IIndeed for many experiments the main subjects are psychology students!  In a {{meta-analysis}} where studies had also been performed in cultural settings which were not WEIRD, they found that cognitive and perceptual results that had been thought to be fundamental to human nature, for example the {{muller-lyer illusion}}, turn out to vary between cultures.
        )

    [wizard of oz prototyping] =&gt; Array
        (
            [slug] =&gt; wizard of oz prototyping
            [parent] =&gt; 
            [name] =&gt; Wizard of Oz prototyping
            [canonical] =&gt; 
            [see] =&gt; 
            [description] =&gt; This is a form of {{prototyping}} where some aspect of the interface that would be expected to be performed by a computer is instead performed by a human researcher, usually secretly. This can be used to try out ideas early before they are fully implemented, or even to explore technology that has not yet been fully developed.
        )

)


  -->

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<ul class="glossary_list">
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/a-b test">A&ndash;B test</a></span><!--  Array
(
    [slug] =&gt; a-b test
    [parent] =&gt; 
    [name] =&gt; A&amp;ndash;B test
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; A&amp;ndash;B test is a form of automated {{usability evaluation}}, used particularly on the web. It involves releasing two (or more) minor variants of an application, A and B, for example two different colour schemes or positions for a {{call-to-action button}}. Metrics are gathered automatically, such as {{click-through rate}} or {{time on page}}, and these are used to determine which of the variants is best.
)
  --></li>
  <li ><span class="name">ACM CHI</span> - See <span class="has_content"><a href="https://alandix.com/glossary/hcibook/chi conference">CHI conference</a></span><!--  Array
(
    [slug] =&gt; acm chi
    [parent] =&gt; 
    [name] =&gt; ACM CHI
    [canonical] =&gt; 
    [see] =&gt; chi conference
    [description] =&gt; 
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/acm conference">ACM conference</a></span><!--  Array
(
    [slug] =&gt; acm conference
    [parent] =&gt; 
    [name] =&gt; ACM conference
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; ACM is one of the major international organisations for computing. ACM conferences such as {{CHI}} are often among the most prestigious in their areas.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/borrowed methods">borrowed methods</a></span><!--  Array
(
    [slug] =&gt; borrowed methods
    [parent] =&gt; 
    [name] =&gt; borrowed methods
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; Methods derived from  other disciplines, for example psychology, where controlled experiments typically have a single cause and are in highly controlled environments. Care must be taken, because interaction studies, even in lab settings, almost always have multiple causes and open situations.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/chi conference">CHI conference</a></span><!--  Array
(
    [slug] =&gt; chi conference
    [parent] =&gt; 
    [name] =&gt; CHI conference
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; Annual ACM Conference on Human Factors in Computing Systems
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/claims analysis">claims analysis</a></span><!--  Array
(
    [slug] =&gt; claims analysis
    [parent] =&gt; 
    [name] =&gt; claims analysis
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; A method developed by Carroll and Rosson, which seeks to better integrate activities directed at understanding with those directed at design. DOI: &lt;doi&gt;10.1145/146802.146834&lt;/doi&gt;
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/cognitive load">cognitive load</a></span><!--  Array
(
    [slug] =&gt; cognitive load
    [parent] =&gt; 
    [name] =&gt; cognitive load
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; The amount of mental resources (e.g. memory, attention) needed for a task or activity.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/conscious thinking">conscious thinking</a></span><!--  Array
(
    [slug] =&gt; conscious thinking
    [parent] =&gt; 
    [name] =&gt; conscious thinking
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; These are the thoughts that you are explicitly aware of having: what you would answer if asked &quot;What are you thinking of now?&quot;. The conscious mind is extremely powerful, allowing us to think rationally and logically, but it is also limited. In particular, your conscious system of thought likes to have a single model of the world and is really bad at probability. Contrast with {{subconscious reactions}}.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/constant area visualisation">constant area visualisation</a></span><!--  Array
(
    [slug] =&gt; constant area visualisation
    [parent] =&gt; 
    [name] =&gt; constant area visualisation
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; A visualisation for hierarchical data in which the area of each part reflects the number or size of the items it represents (e.g. a {{TreeMap}} or {{PieTree}})
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/controlled environments">controlled environments</a></span><!--  Array
(
    [slug] =&gt; controlled environments
    [parent] =&gt; 
    [name] =&gt; controlled environments
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; In physics and other sciences, scientists use very pure substances with very precise instruments to reduce the variability in a study. In HCI we can sometimes emulate this, controlling conditions to reduce the variability in our study ({{reduce noise}}). For example, in a user test we might ask people to use a mobile phone to perform the same tasks in the same location with similar levels of sound and distractions. The downside of this is that it can sometimes reduce {{ecological validity}}, making the resulting conditions less like the real world.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/controlled experiment">controlled experiment</a></span><!--  Array
(
    [slug] =&gt; controlled experiment
    [parent] =&gt; 
    [name] =&gt; controlled experiment
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; Controlled experiments follow a strict protocol, a predefined number of trials, often in a laboratory setting. In HCI, controlled experiments may influence results. For example, experts may behave more like novices in the artificial  environment of a lab experiment, being more careful about their actions and monitoring the results. Typically, controlled experiments have to sacrifice {{ecological validity}}, being less like the equivalent real-world activity. Contrast with {{ethnographic methods}} and {{in-the-wild}} studies. 
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/controlled tasks">controlled tasks</a></span><!--  Array
(
    [slug] =&gt; controlled tasks
    [parent] =&gt; 
    [name] =&gt; controlled tasks
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; Restricting tasks to enable more valid study of individual variables: for example, participants are in a real situation, but instead of doing what they like, they are given a scripted task to perform. While some realism is lost in terms of the chosen task, this increases the level of {{ecological validity}} in the environment.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/coping mechanisms">coping mechanisms</a></span><!--  Array
(
    [slug] =&gt; coping mechanisms
    [parent] =&gt; 
    [name] =&gt; coping mechanisms
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; The resources that people draw on when they find ways to manage a difficult task, whether consciously or unconsciously. While this is useful for getting a job done, for the designer it can mean that usability problems may be hidden. {{Distractor tasks}} are one way to deal with this.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/data journals">data journals</a></span><!--  Array
(
    [slug] =&gt; data journals
    [parent] =&gt; 
    [name] =&gt; data journals
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; These are academic journals that primarily publish documented data. This is in contrast to traditional journals, which may publish data, but only as some form of addendum to a paper that is primarily about the analysis and interpretation of the data.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/data detector">data detector</a></span><!--  Array
(
    [slug] =&gt; data detector
    [parent] =&gt; 
    [name] =&gt; data detector
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; A data detector scans text for terms such as names, post codes or numbers in order to make live links to related information, or in other ways help the user.  They may use lookups in dictionaries or databases for {{named entiries}} (movie titles, names of places), {{regular expressions}} for pattern structured items (such as book ISBNs or telephone numbers), or more complex rules.  You probably have encountered datadetectors in email messages identifying URLs to make them live links, or dates and times to suggest adding a caneldar event. 
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/demonic intervention">demonic intervention</a></span><!--  Array
(
    [slug] =&gt; demonic intervention
    [parent] =&gt; 
    [name] =&gt; demonic intervention
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; Creating extreme experimental situations to {{increase effect}} size.
)
  --></li>
  <li ><span class="name"><a href="https://alandix.com/glossary/hcibook/demonic interventions">demonic interventions</a></span><!--  Array
(
    [slug] =&gt; demonic interventions
    [parent] =&gt; 
    [name] =&gt; demonic interventions
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; 
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/design space">design space</a></span><!--  Array
(
    [slug] =&gt; design space
    [parent] =&gt; 
    [name] =&gt; design space
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; The range of alternative design choices that can be combined in different ways, for example synchronous vs asynchronous, domain specific vs generic. The design space may be represented in a matrix of different semi-independent  choices, but also may be more complex.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/ecological validity">ecological validity</a></span><!--  Array
(
    [slug] =&gt; ecological validity
    [parent] =&gt; 
    [name] =&gt; ecological validity
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; The ecological validity of a test, study or experiment is the extent to which it is like the real world. Performing a {{controlled experiment}} in a laboratory would usually have low ecological validity, whereas an {{ethnographic study}}, observing people in their own workplace, would have high ecological validity.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/elderly users">elderly users</a></span><!--  Array
(
    [slug] =&gt; elderly users
    [parent] =&gt; 
    [name] =&gt; elderly users
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; Older users often have different characteristics from younger ones: for example, on average poorer eyesight or problems with short-term memory. However, this said, there is also a wide variation between different users of any age group and, of course, similarities between ages; for example, many younger people have poor eyesight.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/empirical evaluation">empirical evaluation</a></span><!--  Array
(
    [slug] =&gt; empirical evaluation
    [parent] =&gt; 
    [name] =&gt; empirical evaluation
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; This is when a system or aspect of a system is evaluated through actual data, whether gathered in a {{laboratory experiment}} or {{in the wild}}. Alternatives would be to use some form of {{expert evaluation}} or {{theoretical analysis}}.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/ethnography">ethnography</a></span><!--  Array
(
    [slug] =&gt; ethnography
    [parent] =&gt; 
    [name] =&gt; ethnography
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; A form of {{qualitative research}} based strongly on observation of real situations. A particular focus of {{ethnography}} is to understand a situation from the point of view of the people involved, to become encultured into their patterns of thought, rather than to impose one's own models, theories or values. Experienced ethnographers typically resist any attempt to claim {{generalisability}} of their work, emphasising the unique nature of each situation and context. However, in practice they are very good at bringing out aspects of the situation that inform similar situations elsewhere.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/experimental error">experimental error</a></span><!--  Array
(
    [slug] =&gt; experimental error
    [parent] =&gt; 
    [name] =&gt; experimental error
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; No interesting experiment gives a precise and unambiguous result; there is always a margin of error. For example, if you sample 100 people out of the workforce of a large company, by chance you might choose those who are unusually tall or short, or those who are unusually happy or unhappy with the systems they use. Furthermore, there may be limits to the accuracy of the measurement devices you use, although this is more of a problem in physical rather than human sciences. Where the error is due to random effects, and these are understood, you may be able to estimate the margin of error, for example the {{standard error}} of the mean.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/experimenter effects">experimenter effects</a></span><!--  Array
(
    [slug] =&gt; experimenter effects
    [parent] =&gt; 
    [name] =&gt; experimenter effects
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; A particular type of {{context effect}} where something about the experimenter (for example their mood) affects the responses of the subjects to the tasks.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/expert evaluation">expert evaluation</a></span><!--  Array
(
    [slug] =&gt; expert evaluation
    [parent] =&gt; 
    [name] =&gt; expert evaluation
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; Evaluation carried out by a usability expert rather than an actual user. These are often used for early assessment of a system to avoid the costs of a full {{usability evaluation}}. Note that the term 'expert' here refers to usability or UX expertise, not expertise in the domain of the system. Examples of expert evaluation include {{cognitive walkthrough}} and {{heuristic evaluation}}.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/expert slip">expert slip</a></span><!--  Array
(
    [slug] =&gt; expert slip
    [parent] =&gt; 
    [name] =&gt; expert slip
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; An expert slip is a form of error that is more frequently performed by an expert. Whilst novices may make errors due to lack of knowledge or practice, expert slips are often about performing tasks quickly or with less attention. They are typically infrequent, but may be more damaging and may be noticed far later as experts do not usually need to check the results of their actions as often as novices.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/file tree visualisation">file tree visualisation</a></span><!--  Array
(
    [slug] =&gt; file tree visualisation
    [parent] =&gt; 
    [name] =&gt; file tree visualisation
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; This is an outline-style {{visualisation}} similar to that found in many operating system file-system views. A similar visualisation can be used for other forms of {{hierarchical data}}.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/fine positioning tasks">fine positioning tasks</a></span><!--  Array
(
    [slug] =&gt; fine positioning tasks
    [parent] =&gt; 
    [name] =&gt; fine positioning tasks
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; A task requiring fine motor skills and direct gaze, for example selecting a small target with an on-screen pointer.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/fitts' law">Fitts' Law</a></span><!--  Array
(
    [slug] =&gt; fitts' law
    [parent] =&gt; 
    [name] =&gt; Fitts' Law
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; {{Paul Fitts}} found that, for simple pointing tasks, {{task completion time}} is proportional to the {{Index of Difficulty (IoD)}}, which is essentially the logarithm of the distance to target divided by the target size: IoD = log2 ( distance to target/target size ). While Fitts' original research was on physical one-dimensional pointing alternating between two metal strips, Fitts&rsquo; Law has been found to hold for many kinds of pointing tasks, with a wide variety of devices, over multiple orders of magnitude. Although Fitts&rsquo; Law holds in many situations it is not universal; crucially it depends on situations where there is {{hand&ndash;eye coordination}} and where movement error is proportional to distance moved. 
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/five users">five users (the myth)</a></span><!--  Array
(
    [slug] =&gt; five users
    [parent] =&gt; 
    [name] =&gt; five users (the myth)
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; Often it is said that five users are enough for {{usability testing}}. This had some truth in the particular original context of {{iterative software development}}, where only enough issues needed to be uncovered for the next cycle of re-development. However, it is certainly not sufficient for statistical purposes.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/font size">font size</a></span><!--  Array
(
    [slug] =&gt; font size
    [parent] =&gt; 
    [name] =&gt; font size
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; The size of characters in a {{font}} is usually measured in points, where a printer's point is 1/72 of an inch. So the tall characters in a &lt;span style=&quot;font-size:12pt&quot;&gt;12pt font&lt;/span&gt; are around 1/6 of an inch high, whereas a &lt;span style=&quot;font-size:14pt&quot;&gt;14pt font&lt;/span&gt; is about 1/5 of an inch and &lt;span style=&quot;font-size:7pt&quot;&gt;7pt font&lt;/span&gt; is about 1/10 of an inch. However, the exact size does vary between fonts. On screen the physical size of pixels (the {{screen resolution}}) varies. Old displays often used to have around 70 pixels per inch, so a point and a pixel were nearly the same, but now that varies a lot more, particularly for phone displays and retina displays. The device tries to choose a pixel-height that closely matches the paper dimensions of the desired font. If the precise screen size of characters matters, the font size may be measured in pixels.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/formative evaluation">formative evaluation</a></span><!--  Array
(
    [slug] =&gt; formative evaluation
    [parent] =&gt; 
    [name] =&gt; formative evaluation
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; Focused on making the system better, formative evaluation is performed on the design artefacts (sketch, prototype, or experimental system) during the cycles of design&ndash;build&ndash;
test. Its form varies from {{expert evaluation}} to large-scale {{user testing}}, and its primary purpose is to uncover usability or experience problems for the next cycle. Contrast with {{summative evaluation}}.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/hawthorne effect">Hawthorne effect</a></span><!--  Array
(
    [slug] =&gt; hawthorne effect
    [parent] =&gt; 
    [name] =&gt; Hawthorne effect
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; This when subjects in a study or experiment behave differently because they know they are being observed.  For example in an educational or work setting, subjects may pay more attention to a task when they know they are being watched and recorded.  This may simply life or depress oerall performace, but is particlarly problematic when it casues {{bias}}, in particular, if subjects are aware that the pwerson organising the study or observing the study has an interest in a particular outcome.  In {{user studies}} this often occurs when new software is being trialed.  Subjects may try harder at the favoured system, or give better subjcetive assessments, just to be nice.
)
  --></li>
  <li ><span class="name">HCI</span> - See <span class="has_content"><a href="https://alandix.com/glossary/hcibook/human-computer interaction">Human&ndash;Computer Interaction</a></span><!--  Array
(
    [slug] =&gt; hci
    [parent] =&gt; 
    [name] =&gt; HCI
    [canonical] =&gt; 
    [see] =&gt; human-computer interaction
    [description] =&gt; 
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/hci studies">HCI studies</a></span><!--  Array
(
    [slug] =&gt; hci studies
    [parent] =&gt; 
    [name] =&gt; HCI studies
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; Research in {{HCI}} often involves some form of study with people: sometimes using a {{prototype}}, sometimes in some form of {{focus group}} or {{interview}}, sometimes in a more experimental situation closer to pure psychology. The methods used are often similar to the {{user studies}} or {{user experience studies}} used by {{usability practitioners}} during {{user interface development}}, but the aims are different.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/human-computer interaction">Human&ndash;Computer Interaction</a></span><!--  Array
(
    [slug] =&gt; human-computer interaction
    [parent] =&gt; 
    [name] =&gt; Human&amp;ndash;Computer Interaction
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; This is the discipline focused on understanding of the way people use and are impacted by computer technology and the way that technology can be designed to better serve human needs. This includes single users interacting directly with devices, but also the impact of computers at the level of work groups, families, organisations and communities.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/image recognition">image recognition</a></span><!--  Array
(
    [slug] =&gt; image recognition
    [parent] =&gt; 
    [name] =&gt; image recognition
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; Software that uses algorithms to interpret image data, either static pictures or video. For example, it might be used to recognise faces in a picture so that they can be more easily labelled, or to recognise hand gestures using the computer's camera. Before {{GPS}} was common in phones, some applications would match the image on the phone with known landmarks to enable  location-specific services such as historical information or geo annotation. Similar techniques are also common in {{augmented reality}} systems that overlay digital imagery over a live feed of the real world. The accuracy of the image recognition can affect the {{user experience}}.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/in-the-wild">in-the-wild</a></span><!--  Array
(
    [slug] =&gt; in-the-wild
    [parent] =&gt; 
    [name] =&gt; in-the-wild
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; An {{ethnographic study}} is carried out in the normal context of the subjects of the study, for example observing people in their own workplace. It is a form of {{in the wild}} study; these have high {{ecological validity}} but hold their own specific challenges, such as {{replication}} and control of {{variability}}.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/index of difficulty">index of difficulty (IoD)</a></span><!--  Array
(
    [slug] =&gt; index of difficulty
    [parent] =&gt; 
    [name] =&gt; index of difficulty (IoD)
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; The logarithm of the distance to target divided by the target size: IoD = log&lt;sub&gt;2&lt;/sub&gt; ( distance to target/target size ). Used in {{Fitts' Law}}.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/individual differences">individual differences</a></span><!--  Array
(
    [slug] =&gt; individual differences
    [parent] =&gt; 
    [name] =&gt; individual differences
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; Differences between subjects that may influence the effect being studied. For some studies these individual differences can mask the thing being examined (create {{noise}}). Ways to reduce the impact of individual differences in such situations include using a very {{narrow user group}}, having the same users perform on different systems (a {{within-subjects design}}), and choosing participants of the same age and experience to {{reduce noise}}. Each of these has implications for the {{validity}} of results. Within {{interaction design}} and {{user experience design}} it is crucial to remember that people are different. Sometimes you have to create a 'one size fits all' application, but if you can understand differences between users this can lead to better designs, whether different applications targeted at different user groups, {{customisation}} options within a single application, or {{intelligent interfaces}} that adapt themselves to the user.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/intelligent interfaces">intelligent interfaces</a></span><!--  Array
(
    [slug] =&gt; intelligent interfaces
    [parent] =&gt; 
    [name] =&gt; intelligent interfaces
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; These are systems that use some form of {{artificial intelligence}} or {{machine learning}} as part of {{user interaction}}. Many of us will see examples of this daily as web sites adapt content and especially adverts according to models based on our past behaviour. More advanced systems might try to help us to complete tasks or maybe automate repeated tasks based on examples.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/iterative development">iterative development</a></span><!--  Array
(
    [slug] =&gt; iterative development
    [parent] =&gt; 
    [name] =&gt; iterative development
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; A software design cycle that includes repeated stages of evaluation of evolving designs, prototypes or systems. The two main kinds of evaluation are {{formative evaluation}} at each stage to improve the design and {{summative evaluation}} at the end to assess whether the final design is sufficiently good.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/iterative evaluation">iterative evaluation</a></span><!--  Array
(
    [slug] =&gt; iterative evaluation
    [parent] =&gt; 
    [name] =&gt; iterative evaluation
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; The {{formative evaluation}} in {{iterative development}}
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/learning effects">learning effects</a></span><!--  Array
(
    [slug] =&gt; learning effects
    [parent] =&gt; 
    [name] =&gt; learning effects
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; A type of {{order effect}} where a user is better at a second test because they have already got used to the general ideas of an application in the first test. 
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/likert scale">Likert scale</a></span><!--  Array
(
    [slug] =&gt; likert scale
    [parent] =&gt; 
    [name] =&gt; Likert scale
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; A scale to measure degrees of agreement or satisfaction. The values are often coded as numbers and there is an order but otherwise no specific meaning to the values. This is {{ordinal data}}. &lt;br&gt; An example of survey question using a Likert scale might be:&lt;br&gt; The top level menu items were:  unintelligible &ndash; 1 &ndash; 2 &ndash; 3 &ndash; 4 &ndash; 5 &ndash; always easy to interpret.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/matching subjects">matching subjects</a></span><!--  Array
(
    [slug] =&gt; matching subjects
    [parent] =&gt; 
    [name] =&gt; matching subjects
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; When the same subject repeats a test under different conditions (e.g. evaluating two systems) there may be {{learning effects}}. One way around this is to have different subjects for each condition, but to have two or more subjects who are very similar (in gender, age, skills), and to allocate one from each pair (or matched group) to each condition. Matching subjects makes results more robust, requiring fewer assumptions, but typically has less {{statistical power}} than a {{within-subjects experiment}}.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/menu navigation">menu navigation</a></span><!--  Array
(
    [slug] =&gt; menu navigation
    [parent] =&gt; 
    [name] =&gt; menu navigation
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; Using menus as an interaction mechanism to find one's way around a system.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/modal dialog">modal dialog</a></span><!--  Array
(
    [slug] =&gt; modal dialog
    [parent] =&gt; 
    [name] =&gt; modal dialog
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; A modal dialog prevents other forms of user interaction while it is showing.  This is suitable for situations where it would be inappropriate for the user to do other interactions, for example where there has been some sort of event (such as a network failure) that requires immediate attention, or some action, such as 'save file' that should be completed before continuing.    This is in contrast to a {{non-modal dialog}}.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/muller-lyer illusion">M&uuml;ller&ndash;Lyer illusion</a></span><!--  Array
(
    [slug] =&gt; muller-lyer illusion
    [parent] =&gt; 
    [name] =&gt; M&amp;uuml;ller&amp;ndash;Lyer illusion
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; A well-known optical illusion: there are two horizontal parallel lines of equal length, the top one bounded by outward-facing arrows and the lower one by inward-facing arrows. The lower line looks longer, though it is the same length. The illusion was described by Franz Carl M&uuml;ller-Lyer, a German sociologist, in 1889.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/non-modal dialog">non-modal dialog</a></span><!--  Array
(
    [slug] =&gt; non-modal dialog
    [parent] =&gt; 
    [name] =&gt; non-modal dialog
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; A non-modal dialog allows other forms of user interaction while it is showing.  This is suitable for tool palettes, or helpful suggestions such as intelligent help or spelling corrections.  This is in contrast to a {{modal dialog}}.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/peripheral vision">peripheral vision</a></span><!--  Array
(
    [slug] =&gt; peripheral vision
    [parent] =&gt; 
    [name] =&gt; peripheral vision
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; Where a person is not looking directly at something, but it is still visible out of their central vision. Human peripheral vision is not accurate enough for fine {{positioning tasks}}.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/pietree visualisation">PieTree</a></span><!--  Array
(
    [slug] =&gt; pietree visualisation
    [parent] =&gt; 
    [name] =&gt; PieTree
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; The PieTree is an interactive {{constant area visualisation}} for hierarchical data with some form of numerical attribute including values at the nodes &ndash; for example in a website where there are visits to both the main page of a section and also to sub-pages. The visualisation starts off like a standard pie chart where each segment represents a branch of the tree (e.g. section of the site), except there is also a small circle in the middle representing the value at the root (e.g home page). If any of the segments is selected it breaks into smaller segments for each sub-branch, and so on. 
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/pointing task">pointing task</a></span><!--  Array
(
    [slug] =&gt; pointing task
    [parent] =&gt; 
    [name] =&gt; pointing task
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; A class of low-level device interaction task where a mouse, trackpad, stylus or finger is used  to move towards a target or follow some sort of path. This is typically to target an element onscreen in order to act on it, for example to drag it or select it. The time for positioning tasks often satisfies some variant of {{Fitts' Law}}. 
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/pre-registration">pre-registration</a></span><!--  Array
(
    [slug] =&gt; pre-registration
    [parent] =&gt; 
    [name] =&gt; pre-registration
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; A way to avoid the {{file drawer effect}} by recording a statement before starting an experiment to specify the hypothesis being tested and which statistical technique will be used. This forces justification of the reasons for any {{post-hoc hypothesis}}. It is standard practice in many areas of science, and becoming so in {{HCI}}.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/public domain">public domain</a></span><!--  Array
(
    [slug] =&gt; public domain
    [parent] =&gt; 
    [name] =&gt; public domain
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; This is when the various materials used or produced in research are made available to everyone in some publicly accessible form. These materials include instructions, software (if applicable), and of course the raw study data, whether this is survey reports, video, or keystroke logging, as well as derived data, all the way to the data that lies behind the graphs in your published papers.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/publication bias">publication bias</a></span><!--  Array
(
    [slug] =&gt; publication bias
    [parent] =&gt; 
    [name] =&gt; publication bias
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; If only {{positive results}} are publshied, then it may appaer that they are more {{significant}} (in all senses of the word) than they really are.  This is becasue of you do enough experiments or studies, then by raodm chance one of them will come up 5% significant about 1 time in 20. Publication bias occurs artly because researchers self-select to report things that are most impressive, but also because journal and conference reviewers may not accept papers with {{negative results}}. In {{qualitative}} studies, there can be similar effects, if you look at enough people, or enough events you will see some interesting things, and may tend to report these leaing to a sense that they are common, whereas they may not be at all typical.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/publish or perish">publish or perish</a></span><!--  Array
(
    [slug] =&gt; publish or perish
    [parent] =&gt; 
    [name] =&gt; publish or perish
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; A cultural definition of academic success that requires peer-reviewed publication of research results.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/qualitative methods">qualitative methods</a></span><!--  Array
(
    [slug] =&gt; qualitative methods
    [parent] =&gt; 
    [name] =&gt; qualitative methods
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; Research methods such as rich observations, ethnography, or post-experiment interviews, which are suited to exploratory research, revealing the processes and mechanisms by which something occurs and answering how and why questions. Contrast with {{quantitative methods}}.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/quantitative data">quantitative data</a></span><!--  Array
(
    [slug] =&gt; quantitative data
    [parent] =&gt; 
    [name] =&gt; quantitative data
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; Any data based on numbers or measurable values. This may include objectively measurable values such as {{task completion times}} or more subjective data such as {{opinion polls}}. Contrast with {{qualitative methods}}.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/replichi">RepliCHI</a></span><!--  Array
(
    [slug] =&gt; replichi
    [parent] =&gt; 
    [name] =&gt; RepliCHI
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; An initiative of ACM CHI to increase {{repeatability}}, which led to the addition of a &ldquo;validation and refutation&rdquo; category in some subsequent conferences, and to long-term changes in the ACM {{CHI Conference}} publication guidelines.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/representative sample">representative sample</a></span><!--  Array
(
    [slug] =&gt; representative sample
    [parent] =&gt; 
    [name] =&gt; representative sample
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; A small group who exhibit the typical characteristics of a larger group. Results from the study of a representative sample can be extrapolated to the larger group. Sometimes this sample may be chosen randomly, or may be deliberately chosen so as to ensure that important features such as gender, age or experience match those of the relevant {{population}} as a whole.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/response time">response time</a></span><!--  Array
(
    [slug] =&gt; response time
    [parent] =&gt; 
    [name] =&gt; response time
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; The time it takes for someone to respond to some sort of event, notification, alarm or cue. This may be affected by the form in which the event is presented (e.g. a loud sound vs a subtle change at the edge of the screen), and by the cognitive state of the user (e.g. waiting attentively or highly focused on another task). In the case when some sort of decision is also needed, then other issues will also be important, such as the number of choices and preparedness or implicit biases of the user.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/restricted device">restricted device</a></span><!--  Array
(
    [slug] =&gt; restricted device
    [parent] =&gt; 
    [name] =&gt; restricted device
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; A method to {{reduce noise}} by limiting the functionality of a device; for example, locking a mobile phone so that it can only use the test app, thereby ensuring that activity is directed toward the aspects being studied.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/restricted system">restricted system</a></span><!--  Array
(
    [slug] =&gt; restricted system
    [parent] =&gt; 
    [name] =&gt; restricted system
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; A method to {{reduce noise}} by limiting the functionality of a system. For example, in a social media application you might disable everything apart from music-related features if these are the focus of your study.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/restricted tasks">restricted tasks</a></span><!--  Array
(
    [slug] =&gt; restricted tasks
    [parent] =&gt; 
    [name] =&gt; restricted tasks
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; A method to {{reduce noise}} by limiting the activity of participants, while still maintaining a level of {{ecological validity}}; for example, giving them a scripted task to perform, but within their normal environment.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/selection bias">selection bias</a></span><!--  Array
(
    [slug] =&gt; selection bias
    [parent] =&gt; 
    [name] =&gt; selection bias
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; This is when the way the people who are considered in a study uninitentionally includes some kinds of people more than others and thus induces a {{bias}} in the way resuts are interpretted.  This may occur due to {{sampling bias}} in the way people are initially selected, or other effects such as {{self-selection}} of participants in study, or participants dropping out.  Note that this affects both {{qualitative}} and {{quantitative}} analysis.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/snowball sample">snowball sample</a></span><!--  Array
(
    [slug] =&gt; snowball sample
    [parent] =&gt; 
    [name] =&gt; snowball sample
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; An initial set of contacts is used as the first set of subjects, and they are then asked to suggest any of their own contacts who might take part in the survey. A danger of this approach is that there may be {{internal non-independence}} if the contacts of each individual are likely to share the feature or ability being investigated &ndash; for example contacts may well share political views, or educational background.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/social network data">social network data</a></span><!--  Array
(
    [slug] =&gt; social network data
    [parent] =&gt; 
    [name] =&gt; social network data
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; Data arising from social networks, such as the number of friends or contacts. Often social network data follows a {{power-law distribution}} and so {{statistical tests}} designed for {{approximately Normal}} data &lt;em&gt;cannot&lt;/em&gt; be used.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/software design">software design</a></span><!--  Array
(
    [slug] =&gt; software design
    [parent] =&gt; 
    [name] =&gt; software design
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; Software design involves many aspects, for example the choice of internal protocols between front-end and back-end services; however, from an HCI point of view, the crucial aspects are those relating to the {{user interface}}, {{user experience}} and the way in which it fits into broader {{socio-technical systems}}.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/software development process">software development process</a></span><!--  Array
(
    [slug] =&gt; software development process
    [parent] =&gt; 
    [name] =&gt; software development process
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; There are many processes by which software is designed and created that relate to the kind of software, application domain and organisation, but those parts that involve any form of interaction with the user typically follow an {{iterative process}}. Initial design activity leads to the making of a demonstrable artefact: from storyboards and sketches to wireframes, hi-res prototypes or a running system. The artefact is subjected to testing or evaluation: {{formative evaluation}} in the early stages and {{summative evaluation}} on a pre-release product.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/sonic enhancement">sonic enhancement</a></span><!--  Array
(
    [slug] =&gt; sonic enhancement
    [parent] =&gt; 
    [name] =&gt; sonic enhancement
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; A way to make clicking an onscreen button more evident by adding sound to simulate a physical effect. More generally, many aspects of an interface can be enhanced by additional audio feedback, such as the crunching paper sound that some systems use when a file is thrown into the (desktop) trash bin. While sometimes provided for aesthetic reasons, this may also add feedback.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/steering task">steering task</a></span><!--  Array
(
    [slug] =&gt; steering task
    [parent] =&gt; 
    [name] =&gt; steering task
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; This can refer to literal steering of a tractor or car (or simulation of these), or may refer to a form of {{pointing tasks}} where the pointer has to be navigated along a path. In the former case, the steering may be used as a {{distractor task}} for another {{primary task}} that is the real purpose of an experiment.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/stemming">stemming</a></span><!--  Array
(
    [slug] =&gt; stemming
    [parent] =&gt; 
    [name] =&gt; stemming
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; Stemming is the reducing of words to their root.  For example, removing the 'ing' from stemming to get 'stem'.  However, even this example shows it is not simple.  The root of 'stemming' is 'stem' not 'stemm'!
&lt;br&gt;
Stemming is used in many free text information retrieval systems to improve the matching algorithms. 
&lt;br&gt;
The &lt;a href=&quot;https://hcibook.com/e3/search/l&quot;&gt;full text search&lt;/a&gt; of &lt;a href=&quot;https://hcibook.com/e3/&quot;&gt;Human-Computer Interaction&lt;/a&gt; uses the most rudimentary stemming - it removes 's' from the ends of words.
There are a small number of 'stop words' which are not stemmed to prevent it from stemming words such as 'fuss', but that is all.
&lt;br&gt;
If you are intersted in more complex forms of stemming, see the (Internet Archive) pages for  the &lt;a href=&quot;https://web.archive.org/web/20060819173645/http://www.comp.lancs.ac.uk/computing/research/stemming/Links/implementations.htm&quot;&gt;Lancaster (Paice/Husk) stemming algorithm&lt;/a&gt; and more recent &lt;a href=&quot;https://github.com/words/lancaster-stemmer&quot;&gt;JavaScript implementation&lt;/a&gt; of it on GitHub.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/subconscious reactions">subconscious reactions</a></span><!--  Array
(
    [slug] =&gt; subconscious reactions
    [parent] =&gt; 
    [name] =&gt; subconscious reactions
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; One of two systems of thought identified in psychology: subconscious and conscious, sometimes also called System 1 and System 2 respectively. Subconscious reactions are based on semi probabilistic associations built up through experience. Sometimes subconscious reactions lead to an immediate action, such as jumping out of the way if we hear the sound of an approaching car; at other times they are more about a feeling or gut reaction &ndash; we are aware of the reaction, but not the reasons for it. Contrast with {{conscious thinking}}.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/subjects">subjects</a></span><!--  Array
(
    [slug] =&gt; subjects
    [parent] =&gt; 
    [name] =&gt; subjects
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; The humans involved in a study. Because the term may sound rather clinical or instrumental, some researchers prefer the terms &lsquo;user&rsquo;, or &lsquo;participant&rsquo; if there is a richer engagement. Both these alternatives have their own connotations, and 'subject' remains the most commonly used in statistics.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/summative evaluation">summative evaluation</a></span><!--  Array
(
    [slug] =&gt; summative evaluation
    [parent] =&gt; 
    [name] =&gt; summative evaluation
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; Focused on checking that the system works and is good enough, summative evaluation is performed at the end of the {{software development process}} on a pre-release product. It may be related to contractual obligations (whether the system meets agreed specifications) or may compare the system with others. Less formally, summative evaluation may simply be an assessment that enough work has been done based on the cumulative evidence from earlier stages. Contrast with {{formative evaluation}}.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/survey data">survey data</a></span><!--  Array
(
    [slug] =&gt; survey data
    [parent] =&gt; 
    [name] =&gt; survey data
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; Data obtained by asking people questions, often utilising an electronic or paper form or through guided interviews. The volume of survey data can often be far higher than is provided by more intensive methods such as {{direct observation}}, {{usability tests}} or more in depth interviews. Closed questions, whose answers are chosen from a fixed set of options, are useful as they generate easy to analyse statistical data, but they often only tell you &lt;em&gt;what&lt;/em&gt; is happening. Typically you need more {{qualitative data}} to help you understand &lt;em&gt;why&lt;/em&gt; and &lt;em&gt;how&lt;/em&gt;, including the {{motivation}} and {{mechanism}}. Such data may be obtained through {{open questions}} in the survey, or through complementary methods.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/target size">target size</a></span><!--  Array
(
    [slug] =&gt; target size
    [parent] =&gt; 
    [name] =&gt; target size
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; In a {{pointing task}} this is the size of the area you want to point at, such as a button or icon. It is used in {{Fitts' Law}} to predict the time it takes to locate the target.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/targeted tasks">targeted tasks</a></span><!--  Array
(
    [slug] =&gt; targeted tasks
    [parent] =&gt; 
    [name] =&gt; targeted tasks
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; Tasks designed to deliberately  expose the effects of an intervention by focusing on the aspects of the system that are being tested, minimising interaction with other elements. For example, if you have added a feature to help users keep track of what they are doing, a {{targeted task}} could include a lot of interruptions. Targeted tasks increase {{effect}} in the {{noise-effect-number triangle}} and so increase {{statistical power}}. However, targeting can be misleading if you are not careful, as the {{targeted task}} may not be representative of the full range of tasks that are likely to be carried out; that is {{generalisation}} can be difficult.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/targeted user group">targeted user group</a></span><!--  Array
(
    [slug] =&gt; targeted user group
    [parent] =&gt; 
    [name] =&gt; targeted user group
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; A group for whom we believe we will see the maximum effect is deliberately chosen. For example, a new menu system would be tested more effectively for short-term memory requirements on an elderly user group who are more likely to have some short-term memory loss, rather than on a younger user group. Targeted user groups increase {{effect}} in the {{noise-effect-number triangle}} and so increase {{statistical power}}. However, targeting can be misleading if you are not careful as the {{targeted user group}} may not be representative of the full range of users who are likely to use the system, therefore {{generalisation}} can be difficult.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/task completion time">task completion time</a></span><!--  Array
(
    [slug] =&gt; task completion time
    [parent] =&gt; 
    [name] =&gt; task completion time
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; The time taken to complete a specified task is often used as a measure when comparing two systems. This may be a high-level task, such as finding a product on an online shopping site; or a low-level task, such as a {{pointing task}} modelled by  {{Fitts' Law}}. 
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/tasks">tasks</a></span><!--  Array
(
    [slug] =&gt; tasks
    [parent] =&gt; 
    [name] =&gt; tasks
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; Experimental or study tasks are the actions that users are specifically asked to perform. Measurements such as {{task completion time}} can be observed and recorded. Tasks can be manipulated to gain {{statistical power}} using the {{noise-effect-number triangle}}.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/temporal data">temporal data</a></span><!--  Array
(
    [slug] =&gt; temporal data
    [parent] =&gt; 
    [name] =&gt; temporal data
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; Data recorded over a period of time, where the time at which events occur is a critical part of the data. This can include very long-term phenomena such as the level of usage of a web site, shorter term such as the trace of user interactions while performing a task, or very fine scale such as some biological measurements. There are special statistical techniques for modelling {{time series}} data.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/treemap">TreeMap</a></span><!--  Array
(
    [slug] =&gt; treemap
    [parent] =&gt; 
    [name] =&gt; TreeMap
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; The TreeMap is a {{constant area visualisation}} invented by Ben Shneiderman for hierarchical data with some form of numerical attribute, for example the sizes of files and folders on a computer disk. The most basic form starts with a rectangular area and then recursively divides the area alternatively horizontally using the total values for each level.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/usability evaluation">usability evaluation</a></span><!--  Array
(
    [slug] =&gt; usability evaluation
    [parent] =&gt; 
    [name] =&gt; usability evaluation
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; This is about evaluating how usable a system is; the term can be read quite broadly, or may be distinguished from evaluating {{user experience}}.There are many ways of evaluating usability: {{expert evaluation}} techniques are useful for early design or when users are difficult to contact, but typically the gold standard is expected to use real users. When evaluating with real users there are still many options from {{controlled laboratory experiments}} to {{in the wild}} studies.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/user experience">user experience</a></span><!--  Array
(
    [slug] =&gt; user experience
    [parent] =&gt; 
    [name] =&gt; user experience
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; Aspects of a system that affect the user's emotional state; that is creating a (usually) positive experience of using the system.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/user experience design">user experience design</a></span><!--  Array
(
    [slug] =&gt; user experience design
    [parent] =&gt; 
    [name] =&gt; user experience design
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; This refers to the parts of the design process and the methods used to ensure a desired {{user experience}}.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/user experience studies">user experience studies</a></span><!--  Array
(
    [slug] =&gt; user experience studies
    [parent] =&gt; 
    [name] =&gt; user experience studies
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; These are studies that attempt to {{evaluate}} or otherwise understand the {{user experience}} of a study. It is possible to measure {{objective}} aspects such as heart rate, but the emotional and personal nature of {{user experience}} mean that more {{qualitative methods}} are often used, or various forms of subjective questionnaire. 
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/user interface">user interface</a></span><!--  Array
(
    [slug] =&gt; user interface
    [parent] =&gt; 
    [name] =&gt; user interface
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; The part of a system that the user interacts with. Typically this is some form of screen-based interface with buttons, menus, etc., such as an app or desktop graphical user interface. However, interaction may be through alternatives such as speech, gesture or physical things in the environment that are sensed by the computer.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/user interface development">user interface development</a></span><!--  Array
(
    [slug] =&gt; user interface development
    [parent] =&gt; 
    [name] =&gt; user interface development
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; The process of creating the user-facing aspects of a system, from initial scoping and design through to coding and deployment. Typically {{iterative development}} is used where there are cycles where some form of {{prototype}} or {{design sketch}} is evaluated in a {{user study}} or {{expert evaluation}}. The design is then altered in the light of the {{formative evaluation}}, leading into another cycle.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/user interface properties">user interface properties</a></span><!--  Array
(
    [slug] =&gt; user interface properties
    [parent] =&gt; 
    [name] =&gt; user interface properties
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; This usually refers to specific generic properties that influence the {{usability}} or {{user experience}} of a system in some way. For example, it is usually the case that interactions are more easily learnt if the interface is {{consistent}}. A {{user interface property}} can be a form of {{generative artefact}} when one deliberately tries to create a system that adheres to the principle, and as such can be hard to {{evaluate}}.
)
  --></li>
  <li ><span class="name">user interface testing</span> - See <span class="has_content"><a href="https://alandix.com/glossary/hcibook/usability evaluation">usability evaluation</a></span><!--  Array
(
    [slug] =&gt; user interface testing
    [parent] =&gt; 
    [name] =&gt; user interface testing
    [canonical] =&gt; 
    [see] =&gt; usability evaluation
    [description] =&gt; 
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/user studies">user studies</a></span><!--  Array
(
    [slug] =&gt; user studies
    [parent] =&gt; 
    [name] =&gt; user studies
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; When a system or context is investigated by using real users. {{User studies}} are often regarded as being the gold standard form of {{evaluation}}, but may not always be possible, for example, if the intended users are difficult to contact or a vulnerable group. 
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/validation">validation</a></span><!--  Array
(
    [slug] =&gt; validation
    [parent] =&gt; 
    [name] =&gt; validation
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; The general process of establishing whether something (an interaction technique, system, theory, design principle, toolkit) is in some sense 'valid' &ndash; correct, true, usable. Within HCI there is often a focus on {{empirical evaluation}} of a system, theory or other artefact after it has been created. However, this is effectively impossible for {{generative artefacts}} (things that create other things) such as toolkits, methodologies or design principles, and then other methods, such as {{justification}} based on reasoning and past literature, become more important.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/visualisation">visualisation</a></span><!--  Array
(
    [slug] =&gt; visualisation
    [parent] =&gt; 
    [name] =&gt; visualisation
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; Methods and systems to make it easier to see trends or other patterns in data or derived results. This varies from simple {{scatter plots}} to more complex information visualisations such as the {{TreeMap}} or {{parallel coordinates}}. Where {{visualisation}} is combined with machine learning or other advanced data analysis techniques, it is referred to as {{visual analytics}}. Despite the 'visual' word in its name, {{visualisation}} is also sometimes used to refer to ways to communicate information through other senses such as auditory versions of graphs.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/weird people">WEIRD people</a></span><!--  Array
(
    [slug] =&gt; weird people
    [parent] =&gt; 
    [name] =&gt; WEIRD people
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; Western, Educated, Industrialized, Rich, and Democratic &ndash; Henrich et al. pointed out that the vast majority of psychological studies use a very specific type of subject, not at all typical of the global population. IIndeed for many experiments the main subjects are psychology students!  In a {{meta-analysis}} where studies had also been performed in cultural settings which were not WEIRD, they found that cognitive and perceptual results that had been thought to be fundamental to human nature, for example the {{muller-lyer illusion}}, turn out to vary between cultures.
)
  --></li>
  <li class="has_content"><span class="name"><a href="https://alandix.com/glossary/hcibook/wizard of oz prototyping">Wizard of Oz prototyping</a></span><!--  Array
(
    [slug] =&gt; wizard of oz prototyping
    [parent] =&gt; 
    [name] =&gt; Wizard of Oz prototyping
    [canonical] =&gt; 
    [see] =&gt; 
    [description] =&gt; This is a form of {{prototyping}} where some aspect of the interface that would be expected to be performed by a computer is instead performed by a human researcher, usually secretly. This can be used to try out ideas early before they are fully implemented, or even to explore technology that has not yet been fully developed.
)
  --></li>
</ul>
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