Experimental research makes a statement about the psychological significance and quality of measurement regarding a diagnostic test. Usually, comparisons are made with other indicators and methods of measurement (e. g. an investigation is made into the relation between two different intelligence test methods. As both methods measure the same construct, the correlation coefficient between the two should be very large.)
A term used to indicate that the test scores are to be interpreted as indicating the test taker's standing on the psychological construct measured by the test. A construct is a theoretical variable inferred from multiple types of evidence, which may include the interrelations of the test scores with other variables, internal test structure, or observations of response processes, as well as the content of the test. In the current standards, all test scores are viewed as measures of some construct; construct validity is synonymous with validity. The validity argument establishes the claim for the construct validity of a test score interpretation or use. Ibid.
The extent to which scores or ratings on an assessment instrument relate to other variables or behaviours according to some theory or hypothesis.