Utility analysis in cognitive ergonomics
People use Ergonomics methods with the aim to improve design by: reducing device interaction time, reducing user errors, improving user satisfaction, and generally improving device usability. Each of the methods consider different aspects of human interaction with artefacts. The methods can be broadly classified as either quantitative or qualitative. The quantitative methods predict either speed of performance (e.g. Keystroke Level Model: KLM, Card et al., 1983), errors (e.g. Systematic Human Error Reduction And Prediction Approach: SHERPA, Embrey, 1983), or both speed and errors (e.g. observation, Drury, 1995). The qualitative methods predict user satisfaction (e.g. questionnaires (Brooke, 1996) and repertory grids (Baber, 1996)), device optimisation (e.g. checklists (Ravden and Johnson, 1989), link analysis (Drury, 1995) and layout analysis (Easterby, 1984)), and user-device interaction (e.g. heuristics (Nielsen, 1992), Hierarchical Task Analysis (HTA, Stammers and Shepherd, 1995), and interviews (Sinclair, 1995)). Thus a fairly wide range of human activity with devices is considered using methods that have a pedigree of up to 50 years in Ergonomics research.