Usability evaluation of software interfaces can take place at various stages in the design process. The character and type of the evaluation is dependent on the stage of development of the interface. In the beginning, qualitatative methods can be very valuable in providing rich information (broad band), and recommendations for improvements in the design, in particular with regard to the conceptual model of the interface. In later stages, quantitative tests are useful to test certain (critical) details of the design and usage, or to collect more objective data concerning the effectivity and efficiency of the interaction with the software application. However, qualitatative tests can also be applied in later stages. The ‘usability goals’ are most important in deciding upon the most appropriate procedure, along with considerations concerning resources.

In the WIT-Lab (Laboratory for Work and Interaction Technology), various types of research are conducted, depending on the usability goals and the settings. A few typical examples of usability tests will be discussed, including the measurement methods.