How similar are personality scales of the “same” construct? A meta-analytic investigation

An underlying assumption of meta-analysis is that effect sizes are based on commensurate measures. If measures across studies do not have the same empirical meaning, then our theoretical understanding of relations among variables will be clouded. Two indicators of scale commensurability were examined for personality measures: (1) correlations among different scales with similar labels (e.g., different measures of extraversion) and (2) score reliability for different scales with similar labels. First, meta-analyses of correlations between many commonly-used scales were computed, both including and excluding scales classified as non-Five-Factor Model measures. Second, subgroup meta-analyses of reliability were examined, with specific personality scale as moderator. Results reveal that assumptions of commensurability among personality measures may not be entirely met. Whereas meta-analyzed reliability coefficients did not differ greatly, scales of the “same” construct were only moderately correlated in many cases. Some improvement to this meta-analytic correlation occurred when measures were limited to those based on the Five-Factor Model. Questions remain about the similarity of personality construct conceptualization and operationalization.