Content validity estimates are essentially systematic, but subjective, evaluations of the appropriateness of the measuring instrument for the task at hand. The term face validity has a similar meaning. However face validity generally refers to “non-expert judgments” of the individuals completing the instrument and / or executives who must approve its use. This doesn’t mean that face validity is not important. Respondents may refuse to cooperate or may fail to treat seriously measurements that appear irrelevant to them. Managers may refuse to approve projects lacking in-face validity. Therefore , to the extent possible, researchers should strive for face validity.
Criterion- Related Validity
It can be of two types: (1) Concurrent Validity (2) Predictive Validity
Concurrent validity is the extent to which one measure of a variable can be used to estimate current score on a different measure of the same or closely related variable. For example, a researcher may be trying to relate social class to the use of savings and loan associations. In a pilot study researcher finds useful relationship between attitudes towars savings and loan associations and social class.
Predictive validity is the extent to which an independent’s future level on some variable can be predicted by his/her performance on a current measurement of the same or different variable. Predictive validity is the primary concern of the applied marketing researcher. Some of the predictive validity questions that confront marketing researchers are:
(1) Will measure of attitudes predict future purchases?
(2) Will a measure of sales in a controlled store test predict future market share?
(3) Will a measure of initial sales predict future sales?.
Construct validity- understanding the factors that underlie the obtained measurement- is the most complex form of validity. It involves more than just knowing how well a given measure works; it also involves knowing why it works. Construct validity requires that the researcher have sound theory of the nature of the concept being measured and how it relates to other concepts.