Construct valdity relates to whether a particular psychometric assessment...
Lead consultant at Test Partnership, Ben Schwencke, explains content validity.
Content validity relates to whether or not a psychological assessment measures all relevant aspects of the intended psychological construct. For example, a psychometric assessment designed to measure “extraversion” is likely to incorporate several distinct sub traits, such as gregariousness, sociality, assertiveness, and enthusiasm. Each of these sub-traits is an equally important aspect of extraversion, and thus an assessment which collectively measures these sub traits can be said to show content validity. Conversely, if a measure of extraversion only measures gregariousness, and omits the other sub traits, this assessment can be said to lack content validity.
Content validity is normally ascertained using a group of subject matter experts, who will each give their opinion regarding the assessments content validity. If a sufficient number of those subject matter experts deems the assessment to measure all the requisite sub traits associated with that construct, then the assessment can be said to show content validity. Unlike construct validity and criterion-related validity, content validation is an inherently subjective process, and relies heavily on the expertise of the subject matter experts themselves.