A valid measure actually measures what it says it will measure. To define a measure as valid, one can assess different types of validity. The type of validity of measurement assessed depends on what the researcher wants to know. Criterion validity is one method for assessing the validity of a measure.

In psychometrics

Psychometrics

Psychometrics is the field of study concerned with the theory and technique of psychological measurement, which includes the measurement of knowledge, abilities, attitudes, personality traits, and educational measurement...

, criterion validity is a measure of how well one variable

Variable (mathematics)

In mathematics, a variable is a value that may change within the scope of a given problem or set of operations. In contrast, a constant is a value that remains unchanged, though often unknown or undetermined. The concepts of constants and variables are fundamental to many areas of mathematics and...

 or set of variables predicts an outcome based on information from other variables, and will be achieved if a set of measures from a personality test

Personality test

-Overview:There are many different types of personality tests. The most common type, the self-report inventory, involves the administration of many questions, or "items", to test-takers who respond by rating the degree to which each item reflects their behavior...

 relate to a behavioral criterion on which psychologist

Psychologist

Psychologist is a professional or academic title used by individuals who are either:* Clinical professionals who work with patients in a variety of therapeutic contexts .* Scientists conducting psychological research or teaching psychology in a college...

s agree.