Underreporting of psychopathology on the MMPI-2: a meta-analytic review.

Meta-analytic techniques were applied to studies of the MMPI-2 in which participants given standard instructions were compared with participants instructed or believed to have been underreporting. Traditional and supplementary indices of underreporting yielded a mean effect size of 1.25, suggesting that underreporting respondents differ from those responding honestly by a little more than 1 standard deviation, on the average, on these scales. Analyses of classification accuracy suggested that several scales are moderately effective in detecting underreporting, although accuracy decreases if participants have been coached about validity scales. Base rates of defensive responding in relevant populations are reviewed, and methodological issues, including research designs, coaching, and incremental validity of supplementary underreporting scales, are discussed.