Comparing Idiothetic, Ipsative, and Normative Indices of Consistency

ABSTRACT Lamiell's (1981) “idiothetic” index has been praised for raising significant conceptual and methodological issues, but Paunonen and Jackson (1986a) indicated that it might not provide any unique information The current study demonstrates that the unique value of the idiothetic index relative to the ipsative, normative, and normative‐ipsative indices is dependent in part upon what information is collected and how it is analyzed Subjects completed inventories on three occasions that assessed seven dispositional variables Interindividual analyses indicated a high correlation between the idiothetic method and two of the other models, whereas intra‐individual analyses indicated a much lower degree of correlation Intra‐individual analyses indicated that the idiothetic method produced higher temporal stability coefficients The idiothetic index provides information not contained in a normative index and it may be more useful to personality researchers for the assessment of temporal stability and for the assessment of traits with extreme base rates