Mixed group validation: A method to address the limitations of criterion group validation in research on malingering detection

Mixed group validation (MGV) is offered as an alternative to criterion grou p validation (CGV) to estimate the true positive and false positive rates o f tests and other diagnostic signs. CGV requires perfect confidence about e ach research participant's status with respect to the presence or absence o f pathology, MGV determines diagnostic efficiencies based on group data; kn owing an individual's status with respect to pathology is not required. MGV can use relatively weak indicators to validate better diagnostic signs, wh ereas CGV requires perfect diagnostic signs to avoid error in computing tru e positive and false positive rates. The process of MGV is explained, and a computer simulation demonstrates the soundness of the procedure, MGV of th e Rey 15-Item Memory Test (Rey, 1958) for 723 pre-trial criminal defendants resulted in higher estimates of true positive rates and lower estimates of false positive rates as compared with prior research conducted with CGV, T he author demonstrates how MGV addresses all the criticisms Rogers (1997b) outlined for differential prevalence designs in malingering detection resea rch. Copyright (C) 2000 John Whey & Sons, Ltd.