# 4 Experts¶

This image shows which evaluators found which usability problems in HE of a banking system.

Each row is an evaluator (n=19) and each column is a flaw (n=16).

Black squares show where evaluator found the problem.

The rows are sorted with most successful evaluators at the bottom.

The columns are sorted with easiest to find problems at right.

Here are some questions you can ask yourself about the graph:

How can you define “Easy” and “Hard” to find problems?

State some reasons a problem may be easy or hard

Is there any problem that

*every*evaluator found?What are the main lessons?

Heuristic evaluation is referred to as **discount evaluation** when **5 evaluators** are used.
For this graph, how well will 5 evaluators do?

This curve shows how many times the benefits are greater than the costs for heuristic evaluation of a sample project using the assumptions discussed in the text. The optimal number of evaluators in this example is four, with benefits that are 62 times greater than the costs.

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