Validity

Validity refers to getting results that accurately reflect the concept being measured. Can be defined in a number of ways. A common approach, called criterion validity, is to correlate measures with a criterion measure known to be valid. When the criterion measure is collected at the same time as the measure being validated the goal is to establish concurrent validity; when the criterion is collected later the goal is to establish predictive validity. Separate from criterion validity is construct validity, where an investigator examines whether a measure is related to other variables as required by theory.Validity cannot exceed reliability.