Title
Reviewing and Extending the Five-User Assumption: A Grounded Procedure for Interaction Evaluation
Abstract
The debate concerning how many participants represents a sufficient number for interaction testing is well-established and long-running, with prominent contributions arguing that five users provide a good benchmark when seeking to discover interaction problems. We argue that adoption of five users in this context is often done with little understanding of the basis for, or implications of, the decision. We present an analysis of relevant research to clarify the meaning of the five-user assumption and to examine the way in which the original research that suggested it has been applied. This includes its blind adoption and application in some studies, and complaints about its inadequacies in others. We argue that the five-user assumption is often misunderstood, not only in the field of Human-Computer Interaction, but also in fields such as medical device design, or in business and information applications. The analysis that we present allows us to define a systematic approach for monitoring the sample discovery likelihood, in formative and summative evaluations, and for gathering information in order to make critical decisions during the interaction testing, while respecting the aim of the evaluation and allotted budget. This approach -- which we call the Grounded Procedure -- is introduced and its value argued.
Year
DOI
Venue
2013
10.1145/2506210
ACM Trans. Comput.-Hum. Interact.
Keywords
Field
DocType
systematic approach,original research,five-user assumption,interaction problem,information application,interaction evaluation,human-computer interaction,grounded procedure,interaction testing,blind adoption,relevant research,usability testing,return on investment,measurement,user experience,human factors,usability
User experience design,Argument,Return on investment,Computer science,Summative assessment,Usability,Knowledge management,Interaction testing,Human–computer interaction,Formative assessment
Journal
Volume
Issue
ISSN
20
5
1073-0516
Citations 
PageRank 
References 
8
0.67
15
Authors
6
Name
Order
Citations
PageRank
Simone Borsci1919.42
Robert D. Macredie288459.67
Julie Barnett3739.90
Jennifer Martin4131.68
Jasna Kuljis540934.35
Terry Young632323.44