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Usability Testing > Task Time - Pg. 14

14 CHAPTER 2 Quantifying User Research Task Time Task time is how long a user spends on an activity. It is most often the amount of time it takes users to successfully complete a predefined task scenario, but it can be total time on a web page or call length. It can be measured in milliseconds, seconds, minutes, hours, days, or years, and is typi- cally reported as an average (see Chapter 3 for a discussion on handling task-time data). There are several ways of measuring and analyzing task duration: 1. Task completion time: Time of users who completed the task successfully. 2. Time until failure: Time on task until users give up or complete the task incorrectly. 3. Total time on task: The total duration of time users spend on a task. Errors Errors are any unintended action, slip, mistake, or omission a user makes while attempting a task. Error counts can go from 0 (no errors) to technically infinity (although it is rare to record more than 20 or so in one task in a usability test). Errors provide excellent diagnostic information on why users are failing tasks and, where possible, are mapped to UI problems. Errors can also be ana- lyzed as binary measures: the user either encountered an error (1 = yes) or did not (0 = no).