Evaluating the Psychometric Effects and Assessment of Inconsistent Responding on the Psychopathic Personality Inventory–Revised in a Correctional Sample

The current study aimed to examine the effects of inconsistent responding on Psychopathic Personality Inventory–Revised (PPI-R; Lilienfeld & Widows, 2005) scale scores and the utility of the IR scale in detecting such responding in a correctional setting. The study employed an internally controlled method of simulating inconsistent responding by inserting ascending levels of computer-generated random responses into PPI-R protocols. Participants were 218 male inmates from a medium-security prison in central Kentucky in the United States. Results indicated that psychometric properties of PPI-R scores were substantially attenuated at as low as 40% of random responding. Additionally, results indicated that an Inconsistent Responding (IR) Scale cut-off of 40 would provide the best balance between sensitivity and specificity in detecting invalid PPI-R protocols. Overall, this study highlighted the utility of the IR Scale in self-report psychopathy measures and the need to consider such response biases in research and clinical settings.

Development and Initial Validation of an Inconsistent Responding Scale for the Youth Psychopathic Traits Inventory

The Youth Psychopathic Traits Inventory (YPI) is widely used in research, but there currently exist no means to identify potentially invalid protocols resulting from careless or random responding. We describe the development of an inconsistent responding scale for the YPI using three archival samples of youths, including two from the United States (juvenile justice and middle school) and one from Germany (vocational training school). We first identified pairs of correlated YPI items and then created a total score based on the sum of the absolute value of the differences for each item pair. The resulting scale strongly differentiated between genuine protocols and randomly generated YPI data (n = 1,000) across samples (AUC values = .88−.92). It also differentiated between genuine protocols and those same protocols after 50% of the original YPI items were replaced with random data (AUCs = .77−.84). Scores on this scale also demonstrated fairly consistent patterns of association with theoretically relevant correlates.

Detecting Inconsistent Responding on the Youth Psychopathic Traits Inventory–Short Form

The Youth Psychopathic Traits Inventory–Short Form (YPI-S) is a convenient measure for assessing psychopathy in settings with constraints on resources. However, the YPI-S does not contain a means of detecting careless or random response styles. The present study describes the development and evaluation of an inconsistent responding scale for the YPI-S using five archival samples that vary in language (English, German, Italian, Dutch) and other participant characteristics (juvenile offenders, adolescent students). Inconsistency scores resulting from the new scale effectively distinguished genuine participant responses from randomly generated cases (area under the ROC curve [AUC] = .85-.90) and from cases in which 50% of original responses were replaced with random data (AUC = .75-.82). The associations between the YPI-S and theoretically relevant correlates were reduced among participants exceeding proposed cutoff scores for profile validity compared with associations among more consistent respondents.