Validity is defined as the extent to which the instrument measures what it purports to measure. For example, a test that is used to screen applicants for a job is valid if its scores are directly related to future job performance. There are many different types of validity, including: content, face validity, criterion-related (or predictive validity), construct validity, concurrent validity, convergent validity and divergent (or discriminant validity) Not to worry, l will limit this discussion to the first four.