The following minimum standards, as applicable, should be met in conducting a validity study. Nothing in these guidelines is intended to preclude the development and use of other professionally acceptable techniques with respect to validation of selection procedures. Where it is not technically feasible for a user to conduct a validity study, the user has the obligation otherwise to comply with these guidelines. See sections 6 and 7 above.
Where samples are combined or compared, attention should be given to see that such samples are comparable in terms of the actual job they perform, the length of time on the job where time on the job is likely to affect performance, and other relevant factors likely to affect validity differences; or that these factors are included in the design of the study and their effects identified.
A selection procedure based upon inferences about mental processes cannot be supported solely or primarily on the basis of content validity. Thus, a content strategy is not appropriate for demonstrating the validity of selection procedures which purport to measure traits or constructs, such as intelligence, aptitude, personality, commonsense, judgment, leadership, and spatial ability. Content validity is also not an appropriate strategy when the selection procedure involves knowledges, skills, or abilities which an employee will be expected to learn on the job.
29 C.F.R. § 1607.14