Summative usability testing is summative evaluation< of a product with representative users and tasks designed to measure the usability (defined as effectiveness, efficiency and satisfaction) of the complete product.
Summative usability testing is used to obtain measures to establish a usability benchmark< or to compare results with usability requirements. The usability requirements should be task-based, and should tie directly to product requirements, including results from analytic tools such as personas, scenarios, and task analysis. Testing may validate a number of objective and subjective characteristics, including task completion, time on task, error rates, and user satisfaction.
The main purpose of a summative test is to evaluate a product through defined measures, rather than diagnosis and correction of specific design problems, as in formative evaluation<. The procedure is similar to a controlled experiment, testing the product in a controlled environment. However, it is common to note usability problems that occur during testing, and to interview the participant after the task to obtain an understanding of the problems.