Usability Assessment Methods

A variety of methods are used for conducting usability assessments to support iterative design refinement.  The method selected depends upon: 1) the complexity of the effort, that is, a new development, a major upgrade, or minor modification of an existing system; and, 2) the point in the development cycle in which the method is to be performed.  Some methods are more suited to early design phases, some to the later phases, and others can be used in any phase.

• Expert assessment - Human Factors specialists analyze function and task data and evaluate designs based on education, expertise, experience, and applicable standards and guidelines.  Typically, three specialists can identify at least 75% of a system's usability problems; however, they generally find different problems from users and/or domain experts.  User input is essential to the design of successful systems.  Human Factors specialists are facilitators in user assessments to ensure that user feedback is understood and considered by the design team and to ensure that redesigns meet applicable Human Factors standards, guidelines, and good practice.  This method is applicable to all design phases.

	Human Factors Engineer performing expert assessment on a prototype of the integrated Terminal Weather System (ITWS).
FAA William J. Hughes Technical Center Human Factors Laboratory