Formative

ii iii Usability testing is an essential skill for usability practitioners – professionals whose primary goal is to provide guidance to product developers for the purpose of improving the ease-of-use of their products. It is by no means the only skill with which usability practitioners must have proficiency, but it is an important one. A recent survey of experienced usability practitioners indicated that usability testing is a very frequently used method, second only to the use of iterative design. One goal of this chapter is to provide an introduction to the practice of usability testing. This includes some discussion of the concept of usability and the history of usability testing, various goals of usability testing, and running usability tests. A second goal is to cover more advanced topics, such as sample size estimation for usability tests, computation of confidence intervals, and the use of standardized usability questionnaires