Detection of underreporting on the MMPI-A in clinical and community samples

The utility of traditional and supplementary underreporting scales in detecting underreporting of symptoms on the MMPI-A was investigated in clinical and community samples of adolescents ages 14 to 17. Half of each group was instructed to complete the MMPI-A as if they were attempting to create an impression of excellent psychological adjustment. The other participants completed the MMPI-A under the standard instructions. Underreporting scales were found to be moderately effective in discriminating standard from underreported profiles. The traditional L and K scales obtained correct classification rates ranging from 68% to 84%. Limited evidence for the incremental validity of supplementary scales over the L and K scales was obtained. Findings support the continued use of L and K for detecting underreporting. Additional research is needed to clarify the utility of supplementary underreporting scales.