In some cases, in fact, there is evidence that the multiple dimensions within a disorder do have different etiologies. Many currently defined disorders appear to represent composites of multiple, separable constructs. Thus, the assignment of a disorder, use of disorder scores, or use of symptom counts as descriptions of clinical functioning or as variables in an analysis is problematic for at least two reasons. First, the scores represent the influence of multiple psychological constructs, so they lack clear theoretical meaning. Second, different individuals are likely attaining the same score through endorsement of different symptoms, so the relative degree of influence of the different constructs varies from person to person (McGrath, 2005). In such cases, the meaning of scores is not clear: The same diagnosis can be assigned to individuals experiencing meaningfully different forms of dysfunction.
