http://tc.eserver.org/publisher/Behavior_Research_Methods,_Instruments_and_Computers A listing of works published by Behavior Research Methods, Instruments and Computers in the field of technical communication. en-us Copyright (c) 2005-08 by the EServer. All rights reserved. tclib-editorial@eserver.org (TC Library Editorial Board) webmaster@eserver.org (Geoffrey Sauer) http://tc.eserver.org/images/newlogo.gif http://tc.eserver.org/dir/Behavior_Research_Methods,_Instruments_and_Computers http://tc.eserver.org/27411.html http://tc.eserver.org/27411.html 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%.