Ambiguous Measures of Unknown Constructs: The MMPI-2 Fake Bad Scale (aka Symptom Validity Scale, FBS, FBS-r)

The Fake Bad Scale (FBS; Symptom Validity Scale) has fundamental psychometric flaws, interpretive problems, and potentially adverse societal consequences that are not appreciated by Ben-Porath et al. (Psychological Injury and Law 2(1), 62–85, 2009a, b). The FBS was constructed without due consideration to scientifically based guidelines for scale development (Clark and Watson, Psychological Assessment 7, 309–319, 1995; Jackson, Psychological Review 78, 229–248, 1971; Nunnally 1978; Holden and Troister, Canadian Psychology 50, 120–130, 2009). After almost two decades in existence, its face, content, and construct validity have not been established in the empirical literature. Oft-cited discriminant studies that appear to support the FBS are premature because of the scale’s unestablished psychometric foundation. In addition, these studies have significant methodological weaknesses that preclude definitive conclusions about what the scale actually measures. We review these weaknesses and recent legal cases that challenge the scale. We recommend that the FBS’s validity and fairness be addressed in an independent scientific review by the Buros Mental Measurement Test Evaluation System, a non-profit center specializing in the evaluation of commercially available tests.