A More Nuanced View of Reliability: Specificity in the Trait Hierarchy. (May 2015)

• Record Type: Journal Article
• Authors: McCrae, Robert R.
• Is Part Of: Personality and social psychology review. Volume 19:Number 2(2015)
• Page Start: 97
• Page End: 112
• Publication Date: 2015-05
• Subjects: Five-Factor Model -- consensual validation -- scale development -- scalar equivalence -- reliability; Personality -- Periodicals; Social psychology -- Periodicals; 155.05
• DOI: 10.1177/1088868314541857
• Languages: English
• ISSNs: 1088-8683

Abstract

Retest reliability is a better predictor of validity than is internal consistency. One explanation for this is item-specific variance, which distinguishes different nuances of a facet and contributes to retest reliability but not internal consistency. Specific variance at the facet level is temporally stable, consensually validated, and heritable; a consideration of the role of specific variance in personality measures leads to a distinction between traits as the intersection (∩) versus the union (∪) of their constituents. I discuss specific variance at the item level and its implications for scale development and argue that retest reliability outpredicts internal consistency because item-specific variance has been shown to be observable, and is probably heritable and stable. I consider some implications of these ideas for the use of single-item scales, the causal interpretation of traits, and the notion of scalar equivalence. Finally, I note that the sources of random error in scales are still poorly understood.