The bucket brigade model of validity

In our view assessments begin with lots of validity - but, step by step, it splashes away.

When examiners first think of a test or exam they imagine a perfect test, with 100% validity.

At each step - as they specify the test, as they write questions and mark schemes, as they select the ones to put in the paper - a little validity is lost.

More validity leaks out if the markers vary in how they award marks, if the grade boundaries are not set so as to maintain perfect standards, and as teachers, selectors or employers make decisions based on the results.

Throughout the process all the participants in assessment must do everything they can to maintain as much validity as possible.

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