Conceptual analysis of psychological test scores and other diagnostic variables.

For the clinician, the validity of a test or assessment technique resides in the range and structural clarity of the information it provides him about the individual client with whom he works. 2 devices, for example, might be equal in forecasting a particular criterion, yet differ widely in their personological implicatons. Analysis of this problem permits specification of 3 levels of evaluation: primary, secondary, and tertiary. The conceptual model defined by these levels would appear to incorporate the kind of information which the diagnostician desires, and which indeed he must have if he is to function in an insightful and fully professional manner. The purpose of this paper is to offer a point of view concerning the meaning of measurement in psychology. Attention is centered on the use or application of such measures, and what they tell the interpreter about the individual who has been tested. Significant prior discussions of the validity issue in testing and diagnosis have sought to classify tests according to the criteria employed in their construction and evaluation (cf. Cronbach & Meehl, 1955), and to specify ways in which discriminations may be sharpened (cf. Campbell & Fiske, 1959). These emphases are important, but nevertheless do not touch on all of the significant facets of meaning subsumed under the concept of validity. The intention here is to present a different perspective, one which stresses the implications of any scale or variable when it is brought to bear upon the analysis of the individual case. From this perspective, the practitioner in testing seeks variables which permit individuated descriptions of the subject who has been tested, forecasts of what he will say or do,