What Personality Scales Measure: A New Psychometrics and Its Implications for Theory and Assessment

Classical psychometrics held that scores on a personality measure were determined by the trait assessed and random measurement error. A new view proposes a much richer and more complex model that includes trait variance at multiple levels of a hierarchy of traits and systematic biases shaped by the implicit personality theory of the respondent. The model has implications for the optimal length and content of scales and for the use of scales intended to correct for evaluative bias; further, it suggests that personality assessments should supplement self-reports with informant ratings. The model also has implications for the very nature of personality traits.