Measuring software usability - a methodology and case studies

A methodology is described for the collection of computer user performance measurements during the evaluation of the usability of software and/or software documentation. The keyboard activity of a user working with a software product on a computer system is timed and recorded by a second computer. This log of stored activity is later played back through the host system for observation and analysis. Examples are shown of how this methodology has been employed in conducting iterative usability evaluations and in testing alternate user-interface designs of a variety of software packages.