Validity (statistics)

Validity in statistics means that a test is measuring what it is supposed to measure. If a test is valid, it means that the results are accurate and reliable. It is like if you are given a test to measure how much you know about a particular topic - if it only asks questions about a different topic, it is not a valid test. To be valid, a test usually has to be well-designed and closely related to the topic it is measuring.