According to Field (2009) when testing for validity, one is effectively testing for ‘evidence that a study allows correct inferences about the question it was aimed to answer or that at test measures what it set out to measure conceptually’ (p. 795). There are three main types of validity. Construct validity refers to whether a test correlates to the theorized construct that it purports to measure. For example, an intelligence test is a test which requires strong evidence for construct validity, since researchers need to be sensitive to the extent to which they are measuring intelligence rather than language or culture differences (Mertens, 2009). The second type of validity is content validity, which is relevant to test which aims to evaluate a specific body of knowledge. For example, a depression scale may lack content validity if it does not represent the entire range of possible items, such as the behavioral dimension. Finally, criterion-related validity is a measure of how well a test is effective at predicting of a construct. This type of validity testing is divided into two types, namely concurrent and predictive validity, where concurrent validity is assessed by correlating a test with another test that has been previously validated. These two tests are taken at the same time. Predictive validity differs in that the one test is taken earlier and is meant as a predictor to a later measure (Mertens, 2009).
The utility of selection methods refers to the value it has in the process of selection.