Analysis of Minnesota Multiphasic Personality Inventory-2-Restructured Form response bias indicators as suppressors or moderators in a medical setting.

Abstract

The use of response bias indicators in psychological measurement has been contentious, with debate as to whether they actually suppress or moderate the ability of substantive psychological indicators to identify the construct of interest. Suppression would indicate that predictor variables contain invalid variance that the bias indicators can suppress, while moderation would indicate differential levels of predictive validity at different levels of bias. Response bias indicators on the Minnesota Multiphasic Personality Inventory (MMPI)-2-Restructured Form (MMPI-2-RF) [infrequent responses (F-r), infrequent somatic responses (Fs), infrequent psychopathology responses (Fp-r), adjustment validity (K-r), uncommon virtues (L-r), symptom validity (FBS-r), and Response Bias Scale (RBS)] were tested to determine whether they suppressed or moderated the ability of the Restructured Clinical Scale 1 (RC1) and Neurologic Complaints (NUC) scale to discriminate between epileptic seizures (ES) and nonepileptic seizures (NES, a conversion disorder that is often misdiagnosed as ES). The MMPI-2-RF was completed by 399 patients with a confirmed diagnosis of ES or NES via Epilepsy Monitoring Unit evaluation. Moderated logistic regression was used to test for moderation, and logistic regression was used to test for suppression. Most of the response bias variables showed a suppressor effect, but moderator effects were not found. These findings extend the use of bias indicators to a psychomedical context.