Reference: Sherman, E. H. Evaluation of User Interfaces. KSL, December, 1990.
Abstract: Evaluation of user interfaces (UIs) has become more sophisticated than a few speed tests of a completed application. Numerous techniques are used now to test a system during all stages of the development. So that the final UI will match the needs of its end users, evaluation should begin early and should continue throughout the lifetime of an application. Methods for evaluation vary from simply reporting observations to experiments and statistical analysis, from the objective results of traditional time trials and questionnaires to subjective musical appreciation. The evaluation procedures appropriate for a given UI depend on the stage of development and the type of interaction. Use of appropriate evaluation techniques increases the likelihood that the application will be successful and may even result in the creation of new human-computer interaction theory.