The forms of evidence you use will vary, depending on the competency and the person you're assessing. There will often be times where you'll use all of the forms described below to make sure that you've covered everything.

Direct evidence

When you watch a person perform a task, you are using direct evidence. The biggest advantage of direct evidence is that you can see for yourself whether the candidate is doing the task properly.

Its main disadvantage is that you can't test a person's broad understanding of the job if they aren't able to physically demonstrate that knowledge in front of you.

This is often the case when the different conditions (called the 'range of conditions') that apply to the task aren't all available to you when you're with the candidate.

Indirect evidence

There are some aspects of competency that are not easy to observe directly, such as a person's understanding of how a task fits into the overall work process, or what they would do in an emergency situation. In these cases, you need to use indirect evidence to assess their competency. Indirect evidence includes simulated demonstrations, questions, scenarios, role plays and projects.

Supplementary evidence

Supplementary evidence is used to verify and support the other evidence you have collected of a person's competence. The most common forms of supplementary evidence are written or oral tests and third party reports.