Verification, Validation, and Testing of Engineered Systems

5.5 BLACK BOX—SPECIAL TESTING

5.5.1 Usability Testing

Purpose

Usability is the ability of a specific group of users to perform a specific set of activities within a specific environment with effectiveness, efficiency and satisfaction. The purpose of usability testing is to find out practical information about how users actually use a system. Ultimately, usability testing ensures that the design of engineered systems will meet the needs of a representative group of users and, very likely, meet the business needs of the company.

Usability testing involves the observation of typical users performing real system tasks, recording what they do, analyzing the results and recommending appropriate changes if needed. Such user feedback on specific features is of particular interest to the developers of systems. In particular, developers are interested in (1) the level of satisfaction typical users may derive from the system, (2) the efficiency with which users can operate the system, (3) the degree to which users can successfully learn and use the system and (4) the amount of errors that typical users may make while operating the system.

Rationale

Usability testing reveals system defects and therefore contributes to the following improvements in the system under test: (1) evaluates functional suitability, that is, whether the system encompass the functionality required by users, (2) evaluates how easy it is to learn and operate the system, that is, whether the users of the system are ...