This paper describes a practical method for evaluating the usability of human-computer interfaces. The paper specifies the requirements of such a method, and then outlines our work in developing a method to meet this specification. The method is based on the conduct of realistic tasks with an interactive system and the subsequent systematic elicitation of end-users' and designers' reactions to the interface using a criterion-based evaluation checklist.
Two practical examples are used to illustrate development of the method: (a) evaluation of a prototype production scheduling system, and (b) comparative assessment of the usability of three prototype user interfaces to a public-access database. The paper discusses some issues raised by the method and considers how it can be further developed.