Spearman's Test Score Model: a Restatement

Abstract

A re-examination of Spearman's (1910) paper led to the conclusion that he did not subscribe to a platonic distinction between true and error scores, or to the restrictive and empirically intractable postulate of constant true scores in repeated measurements with the same test. He argued instead for the reality of possible systematic variations in observed scores under repeated measurements, variations which required determination and not elimination, with an overlay of nonsystematic variations due to factors whose modes of operation were such as to baffle investigation and control. Spearman's distinction was a pragmatic one between the predictable and the unpredictable with theoretical overtones hitherto overlooked in psychometrics, and contained an implied plea for an experimental psychometrics.