Improving user performance

Three studies that demonstrate that traditional, rigorous experimental design can be applied and adapted to constitute excellent troubleshooting tools at various stages in the system design cycle are presented. The first study, which seeks to identify variables that facilitate visual scanning of computer screens, most closely resembles traditional laboratory studies in terms of rigor and experimental control. The second study uses a mixture of quasi-formal experiments and anecdotal observations to identify user problems in a particular system for which a help system is then designed and tested in an iterative fashion. The third study, concerning the redesign of a user manual, uses systematic investigative tools, although not well-controlled experiments, to isolate user problems, and then tests the usability of new versions of the manual iteratively. The findings from these three studies suggest that experimental methods can serve an important function in identifying usability problems and in progressive testing of systems