Construct validity refers to a general approach to test validity that rests on the assumption that validation is theory-based. Construct validity is broadly opposed to operational definition in assuming that the same construct can be assessed fallibly by various measurement instruments. Initially, construct validity was seen as one type of validation among others and was rooted in logical empiricist philosophy of science. More recently, construct validity has come to be seen as the whole of test validity, subsuming other types as lines of evidence in support of construct validity and has become rooted in scientific realism. Recent work has proposed various modifications of the received view embodied in the Standards for Educational and Psychological Measurement.