Abstract: Conventional wisdom inside human factors circles says that the integration of user interface design processes into the software development cycle is the best way to improve the usability of software products. While there is no problem convincing human factors practitioners of this, frequently there is still a need to demonstrate the effectiveness of user interface processes to product development teams and management. Mayhew (1992) suggests that it is not enough to be able to apply human factors knowledge. Successful user interface design must include buy-in from outside of the user interface organization. To demonstrate the effectiveness of a user interface design program, data from usability tests on three versions of a product were analyzed. The oldest version of the product was developed without the inclusion of any user interface design processes. The second version of the product had minimal involvement of user interface practitioners late in the development cycle. The newest version of the product was developed with the user interface design processes fully integrated into the software development cycle. The data indicate that user interface design processes do impact usability, as measured by speed, accuracy, and subjective measures. Furthermore, user interface processes which are part of the software development cycle, as opposed to just a side effort by user interface practitioners, seem to have a much greater impact on usability.

Keywords: Case studies; Design; Email; Evaluation; Implementation; Software development; Usability testing

Originally published: Proceedings of the Human Factors and Ergonomics Society 38th Annual Meeting, 1994, pp. 305-309

Republished: G. Perlman, G. K. Green, & M. S. Wogalter (Eds.) Human Factors Perspectives on Human-Computer Interaction: Selections from Proceedings of Human Factors and Ergonomics Society Annual Meetings, 1983-1994, Santa Monica, CA: HFES, 1995, pp. 354-358.