Independent Croups Design or Between Subjects Design - I

This is called an independent groups design because each part of the web site is tested by a unique set of users. For our example, shown in the table below, this design requires 15 participants and mitigates the potential transfer of learning effects caused by doing one set of tasks prior to performing other similar tasks. In other words, performing Task A may help one to perform Task B, and mask any usability problems associated with Task B. You can also use this design if the tasks are extremely lengthy and there is a possibility that the participants may become fatigued.