ISO standard 9241

ISO 9241 is a standard published by ISO concerning the "Ergonomics of Human System Interaction", which includes many issues considered by HCI or user interface design. In particular, part 11 (ISO 9241-11) includes the three components: System Effectiveness – can the user do what they want to do; System Efficiency – how difficult is it to do it; and System Satisfaction – the emotional repsonse of the user to the system. These three effectiveness, {efficiency}} and satisfaction are often used as core criteria within HCI. In the early years the more productivity oriented effectiveness and efficiency were often cited alone, although now-a-days user experience deisgn focuses much more strongly on satisfaction.