Criterion validity is a measure of how well one variable or test predicts an outcome based on another variable or test. It assesses the effectiveness of a test by comparing it to a benchmark or standard, known as the criterion. This type of validity is crucial in determining whether a test accurately reflects the concept it aims to measure. There are two main types of criterion validity: concurrent validity and predictive validity. Concurrent validity evaluates how well a test correlates with a criterion measured at the same time, while predictive validity examines how well a test forecasts future performance or outcomes. Both types help ensure that assessments are reliable and meaningful.