Further Validation of the Response Inconsistency Scale for the Personality Inventory for DSM-5

Abstract

Assessment of protocol validity is essential for structured personality tests used in clinical decision making. Measures of inconsistent responding allow researchers and clinicians to identify random or careless response patterns that compromise an accurate interpretation of test results. Keeley and colleagues (2016) developed an Inconsistency scale (INC) for the widely used Personality Inventory for DSM-5 (PID-5; Krueger, Derringer, Markon, Watson, & Skodol. 2012. Initial construction of a maladaptive personality trait model and inventory for DSM-5. Psychological Medicine, 42(9), 1879–1890.). The INC produced highly promising results in initial validation studies, and the current study provides a series of additional tests of the adaptability of the INC item pairs across different populations, translations, and versions of the PID-5. Study 1 examines the diagnostic utility of a shortened version of the original INC scale (INC-S) that can be used with the 100-item version of the PID-5; optimum cut scores are identified for this short form adaptation. Study 2 cross-validates the INC-S and compares diagnostic utility to the INC in a sample that completed the full PID-5. Study 3 examines the diagnostic utility of the INC and INC-S using a German translation of the PID-5 with undergraduates and clinical patients. Overall, these validation studies provide robust support for the INC and INC-S scales to discriminate random-generated versus real PID-5 protocols.