Nuanced HEXACO: A Meta-Analysis of HEXACO Cross-Rater Agreement, Heritability, and Rank-Order Stability

Most Five-Factor Model questionnaire items contain unique variance that is partly heritable, stable, and consensually observable, demonstrates consistent associations with age and sex, and predicts life outcomes beyond higher-order factors. Extending these findings to the HEXACO model, we meta-analyzed single-item cross-rater agreement, heritability, and two-year stability using samples from six countries. We analyzed raw item scores and their residual variance and adjusted the estimates for measurement unreliability. Median cross-rater agreement, heritability, and stability estimates were, respectively, .30, .30, and .57 for raw items and .10, .16, and .39 for item residuals. Adjusted for reliability, the respective medians were .46 and .25 for cross-rater agreement, .46 and .39 for heritability, and .87 and .94 for stability. These results are strikingly consistent with FFM-based findings, providing non-dismissible evidence that single items index a partly unique level of the trait hierarchy – personality nuances –with trait properties comparable to those of higher-order traits.