Toward a methodology employing critical parameters to deliver performance improvements in interactive systems

ABSTRACT In the design of interactive systems, overall performance issues tend to receive less attention than provision of functionality. As a result, systems may not always offer perform-ance improvements to their users. In this paper we present some proposals for methods based on the use of application-specific critical parameters, i.e., performance parameters that measure how well the system serves its purpose. We argue that these parameters can provide a basis for dealing with performance issues in design. To construct this basis, there is a need to focus on identifying parameters through field studies, and on constructing models for use in making performance pre-dictions. We provide a number of examples of critical parameters, and discuss problems we have encountered in identifying them and in model construction. We summarise the results of a study of designers working with critical parameters. A final section of the paper discusses the feasibility of introducing critical parameters to HCI design practice