4.7: Controlled Psychologically-oriented Experiments

• Scientific and engineering progress is often stimulated by improved techniques for precise measurement.
• Rapid progress in the designs of interfaces will be stimulated as researchers and practitioners evolve suitable human-performance measures and techniques.
• The outline of the scientific method as applied to human-computer interaction might comprise these tasks:
• Deal with a practical problem and consider the theoretical framework
• State a lucid and testable hypothesis
• Identify a small number of independent variables that are to be manipulated
• Carefully choose the dependent variables that will be measured
• Judiciously select subjects and carefully or randomly assign subjects to groups
• Control for biasing factors (non-representative sample of subjects or selection of tasks, inconsistent testing procedures)
• Apply statistical methods to data analysis
• Resolve the practical problem, refine the theory, and give advice to future researchers
• Managers of actively used systems are coming to recognize the power of controlled experiments in fine tuning the human-computer interface.
• limited time, and then performance could be compared with the control group. Dependent measures could include performance times, user-subjective satisfaction, error rates, and user retention over time.