Discriminant validity

In psychology, discriminant validity or divergent validity tests whether concepts or measurements that are not supposed to be related are actually unrelated.

Campbell and Fiske (1959) introduced the concept of discriminant validity within their discussion on evaluating test validity. They stressed the importance of using both discriminant and convergent validation techniques when assessing new tests. A successful evaluation of discriminant validity shows that a test of a concept is not highly correlated with other tests designed to measure theoretically different concepts.

In showing that two scales do not correlate, it is necessary to correct for attenuation in the correlation due to measurement error. It is possible to calculate the extent to which the two scales overlap by using the following formula where ${\displaystyle r_{xy}}$ is correlation between x and y, ${\displaystyle r_{xx}}$ is the reliability of x, and ${\displaystyle r_{yy}}$ is the reliability of y:

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