The meaning of validity has changed often over the past century (see Kane, 2001). Originally, it was related to whether a test measured what it purported to measure, but in the mid-1950s, the usage of the concept became more complex as different types of validity were identified. Thus, it came to refer to face, content, criterion, and concurrent validity. (Face validity refers to how well the test appears, “on its face,” to measure what it is claimed to measure. Content validity refers to how well the test instrument covers or samples from all aspects or content of the entity or domain it is attempting to measure—for example, to what degree does a test of mastery of a science curriculum adequately sample from all the content ...