Evaluation is an important part of the software life cycle. In HCI, evaluation is a critical component involved throughout the systems development process. Evaluation enables the designers to see what their users really want and whether their system meets up to the requirements.

Formative and Summative Evaluation

Formative Evaluation is used to inform future decision making. This is possible when evaluation is involved as an iterative process throughout the design life cycle. In many cases though, this use of evaluation all the way through the design cycle is not carried out. The type of evaluation that tends to be used is summative evaluation. Summative evaluation involves evaluating the design at the end of the design process. Formative evaluation is recommended over summative evaluation for HCI.

Analytical Testing, Task Analysis and GOMS

GOMS (Card, Moran and Newell, 1983) is an example of analytical testing. The acronym GOMS stands for Goals, Operators, Methods, and Selection procedures. It involves analysing the actions of experts, broken down into operators (or individual acts), to see how efficiently goals can be achieved.

Task Analysis describes the process of breaking down tasks into fundamental components which can then be analysed. GOMS is based around this principle.

Empirical Testing

Empirical testing involves using real users of a system working on a functional design of the system (or prototype). The testing can occur using observation and collection of information, or experimentation. Observation involves watching users at work to gain an insight into behavioural patterns associated with parts of the system. Interviews and questionnaires can also be used to gain user opinions.

Experimentation is a more scientifically oriented approach. The steps involved in experimentation are as follows:

- Outline requirements for system
- Set up the prototype system
- Design the experiment (content and schedule)
- Pilot experiment
- Final experiment
- Final analysis and evaluation

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