User-derived impact analysis as a tool for usability engineering

A unified approach to improved usability can be identified in the works of Gilb (1981, 1984), Shackel (1984), Bennett (1984), Carroll and Rosson (1985), and Butler (1985). We term this approach “usability engineering,” and seek to contribute to it by showing, via a product development case study, how user-derived estimates of the impact of design activities on engineering goals may be made.1