Initial Validation of Short Forms of the SIMS for Neuropsychological Evaluations

Abstract

The Structured Inventory of Malingered Symptomatology (SIMS) is a measure of impression management that covers a range of symptomatology through 75 items and five scales, some of which are particularly relevant for cognitive evaluations. The aims of the current projects were to (1) reduce the length of the SIMS to the items most predictive of symptom validity on the Minnesota Multiphasic Inventory-2-RF, (2) explore the factor structure of the remaining items, and (3) test the degree to which the final scale identifies individuals with inadequate performance validity. The sample consisted of 249 veterans referred for outpatient neuropsychological assessment and completed the SIMS, most of whom also completed the MMPI-2-RF and measures of performance validity. Results identified items from the Neurological Injury (11 items) and Amnestic Disorders scales (8 items) that were most strongly related to its theoretically consistent MMPI-2-RF scales and that two distinct factors corresponding to the original scales were identified on factor analysis. The revised subscales correlated at r = 0.55, and each scale had acceptable internal consistency (α = 0.76–0.84), and the Amnestic and Total Revised SIMS were adequately able to identify individuals failing measures of performance validity. The reliability and validity of the SIMS for Neuropsychological Settings (SIMS-NS) and its Amnestic subscale, despite its brevity, were practically psychometrically equivalent to the original SIMS and one prior short form of the test.