Waterfall User Interaction Design Process

Usability Testing

Once the system (or a suitable subset) is built, actual usability testing can begin. Testing the user interaction relies chiefly on user observation. Notes, interviews, videos, screen captures (e.g., Camtasia), Morae, thinking aloud testing, perhaps some form of heuristic evaluation are the methodologies.

Usability criteria from the UIFS document include:

• Utility, does the system do what is necessary?
• Productivity, the increase in work performance using the product
• Learnability, intuitive navigation, clear metaphors and language
• Memorability, little confusion as to what to do next in a process
• Errors are reduced, minimized and properly handled
• Subjective satisfaction, fits the capabilities and work styles, of user group
• Help and training, does the training or help actually help?

For a product consisting of defined goals, the test objectives can be stated simply, as in, "Accomplish goal X." For menu-driven or more complex software, the test objectives would be smaller problems, such as "Adjust the color of the current object".

The cost of usability design and testing if properly done will be about 10% of project budget; the percentage decreases on larger projects. For intranets or software products, usability spending leads to performance increases of some 150% or better (Norman-Nielsen studies).