ABSTRACT
The focus of Chapter 3 was on the representation of the factors (tasks, users, and system) that influence system performance within a particular context of use. These factors can be represented analytically, by modelling interactions in order to make predictions about performance, and empirically, by representing system components in a simulated or real-world environment and measuring performance with a sample of users. Chapter 5 presented the results of an analytic assessment of IVIS, which was used to compare two existing IVIS and to explore how analytic predictions could be used in evaluation. These predictions are useful at an early stage in product development, when access to prototype systems or samples of users is more restricted, and can give an indication of the potential usability issues with a product or system. Empirical methods are recommended for later stages of the development process, to further investigate the predictions made by analytic methods, using real users and prototypes in order to represent the system with a greater level of fidelity. This chapter presents a case study in which empirical methods were applied to compare two of the most popular IVIS input device types: touch screen and remote controller. The main aim of this case study was to assess how well empirical evaluation methods, selected and described in Chapter 4, could identify usability issues that are specific to these two input types. A set of empirical methods were selected as part of the work presented in Chapter 4, using the flowchart for method selection. These methods are summarised in Table 6.1. As with the analytic methods summary table (Chapter 5), links are made to the KPIs that are measured by the empirical methods.
