by Vivienne Trulock
The word 'heuristic' means expert. So a 'Heuristic Evaluation' of a system is an 'Expert Evaluation'. This expert evaluator uses a checklist of heuristics against which the system (website, multimedia CD ROM, windows application, washing machine) is graded.
It allows the designer of a system or interface to get feedback from other experts in the field.
4 or 5 experts needed
Who can be an expert ?
The designer of a system cannot be the expert evaluator, because they cannot see their own built in assumptions. For example, as I am writing this page I understand what I am trying to explain, but I can only be fairly certain that the readers also understand, if someone else (who knows nothing about the subject) can also understand it. Because the designer is a type of expert, they may not see problems that novice users might have with the system. The designer is also unlikely to be visually, motor or cognitively impaired and it can be impossible to then to comprehend what the system might look like from these perspectives. So the system designer cannot be the systems 'Heuristic Evaluator'.
However, a system designer may be a Heuristic Evaluator of a system another designer has created, as they will likely see at least some of the mistakes the other designer has made. This in fact is the most usual scenario. To increase the likelihood of detecting all possible interface errors, several independent evaluators may be used. According to Jacob Nielson, the recommended number is 5. After 5, the time and cost out way the benefits of finding further errors.
A person who knows a lot about the system can also function as an expert evaluator, as they will have an expert understanding of task flows and expected system outcomes that a designer may not fully understand. These experts can catch errors and mistakes of a nature that a designer might never see.
A person who will use the system is not usually considered an expert in the system. For this reason they are not generally used for Heuristic Evaluation, although users are commonly involved with other evaluation methods such as User Testing and Task Analysis.
Occasionally a person is available who is both a designer and an expert of the system being created. This person is the most likely to find the most errors and therefore are the most valuable team member during the evaluation phases.
As mentioned above, a checklist is required against which to grade the system being evaluated. The list below consists of 9 checks, though others have 10 or 11.
Elements should be listed along with:
The list should be ordered in descending order of severity, from most severe to least, and then by screen.
Experts can pick up many obvious errors...
.. but ultimately the system MUST be tested with real, representative people
Using the screen shots and scenario given, and the Heuristic Evaluation Sheet (.doc) / Heuristic Evaluation Sheet (.rtf), complete a heuristic evaluation of PDA screen designs for a Gastro-Intestinal unit