In an ecologically valid HCI study, in the wild or even in the lab, there are usually multiple causes for effects; that is different possible explanations for the effects you are seeing, several of which are often true. This happens because controls are difficult to implement and individuals and contexts always vary. Claims analysis is a method developed by Carroll and Rosson that specifically embraces multiple causes of the success or failure of systems.
Also used in hcistats2e: Chap. 14: page 177
Used in glossary entries: claims analysis, ecological validity, in-the-wild