Raising the Validity Bar in Test Development

A test is a measurement instrument that measures a particular knowledge, ability or a skill. It is a mental measurement. Like all measures, it must measure the right thing, and it must measure it accurately. These are important notions, referred to as validity and reliability.

Because we cannot observe knowledge or ability directly, we give test takers tasks—often questions—and based on their performance on those tasks, we make inferences about the test taker’s ability.