Beyond the five-user assumption: benefits of increased sample sizes in usability testing.
It is widely assumed that 5 participants suffice for usability testing. In this study, 60 users were tested and random sets of 5 or more were sampled from the whole, to demonstrate the risks of using only 5 participants and the benefits of using more. Some of the randomly selected sets of 5 participants found 99% of the problems; other sets found only 55%. With 10 users, the lowest percentage of problems revealed by any one set was increased to 80%, and with 20 users, to 95%.
Faulkner
Laura
L
Applied Research Laboratories, University of Texas, Austin, Texas 78713-8029, USA. laura@arlut.utexas.edu
D003258:Consumer Behavior; D003625:Data Collection / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D020407:Internet; D011358:Product Surveillance, Postmarketing; D018401:Sample Size; D012984:Software; D013647:Task Performance and Analysis; D014584:User-Computer Interface