Information Technology Reference
In-Depth Information
goals or to make comparisons. The remaining part of this section describes
the method further, and also explains how an evaluation is conducted as
originally proposed.
Heuristic evaluation is essentially subjective. In its original form, the
evaluators, experts in usability (not potential users), inspect the subject for
evaluation, and judge how it complies with a set of recognized usability
principles known as heuristics [4][24]. They inspect it by using it; it is
suggested this is done in several rounds, for example a first round to
explore the interface and obtain a general feel for it, and then one or more
rounds, where each interface item is inspected and judged by using all
heuristics. The evaluators identify general usability problems that users
may encounter. Each problem is given a severity rating (described below).
Sometimes the evaluators also address the problems further, and provide
suggestions on re-design to overcome the problems and improve usability.
The results are recorded, including a description of the problem, its place
of occurrence, which heuristic was violated by the design (it can be more
than one heuristic for each problem), and the severity rating [25]. This
often requires substantial documentation to ensure accuracy and clarity.
The rating can be applied in a variety of ways, but the original scale
used by Nielsen and Molich [5][22] is given here:
1.
Cosmetic problem only. Not necessary to fix unless time is
available in the project.
2.
Minor usability problem. Fixing this problem should be given
low priority.
3.
Major usability problem. Important to fix, this problem should
be given high priority.
4.
Usability catastrophe. It is imperative to fix this problem.
There can also be a fifth item on the scale:
0.
I do not agree to this being a usability problem.
This option (0) can be used when results from several evaluators are
discussed and aggregated (see below).
The severity rating allocated to each problem depends on three factors
[25]:
x
Frequency: is the problem common and affect such interactions
or functions used often or does it happen only on rare
occasions?
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