Creating a Short Usability Metric for User Experience (UMUX) Scale

This paper describes development and initial validation testing of new 4-item usability assessment tool, 'Usability Metric for User Experience' or UMUX. UMUX is intended to measure usability as one component in a multicomponent software assessment suite. It needs to be short, in comparison with the longer, widely-used tool it is designed to replace, to keep the overall software assessment acceptably brief. The basic process of scale construction described is psychometrically adequate. However, UMUX validation in a live test of two corporate software systems known to differ in usability shows that the UMUX score variance is quite large. There were also major qualitative differences between the tested systems. These non-usability-related differences may have influenced both UMUX and SUS scale scores enough, in unknown ways, to make additional UMUX testing on more comparable systems imperative before UMUX is fielded for use.