Engel-Small, Erika A., and Diefendorff, James M.

Journal of Applied Social Psychology, Vol. 36, Issue 2,  Pages 297-320

The present study examined two possible ways of increasing the predictive validity of personality measures: using observer (i.e., supervisor and coworker) ratings and work-specific self-ratings of the Big Five personality factors. Results indicated that among general self-ratings of the Big Five personality dimensions, Conscientiousness was the best predictor of in-role performance, and Agreeableness and Emotional Stability were the best predictors of extra-role performance. Observer ratings of personality accounted for incremental variance in job performance (in-role and extra-role) beyond that accounted for by general self-ratings. However, contrary to our expectations, work-specific (i.e., contextual) self-ratings of personality, generally did not account for incremental variance in job performance beyond that accounted for by general self-ratings.