In an experimental study like a usability test, data are collected on different measures, such as how long it takes to complete a task. Task completion time (called Time on Task) is a dependent variable; among other things, it depends upon the content of each task and upon how experienced each test participant is with the product under study. In a between-subjects design, the values of the dependent variable for one group of participants (for example, the group of participants who have prior experience with the product) are compared with the values for another group of participants (for example, the group of participants who have never used the product before.). In between-subjects designs, responses from a given participant appear in only one group.
