In the second place, though the scale has a variety of employments, one being as input into structured and semi-structured clinical assessments, its primary employment- certainly in research- is as an instrument of scaling. The choice researchers have consistently made to interpret the multidimensional findings as novel insights into the nature of the construct, rather than as bearing on the construct validity of the scale, is an arbitrary one, and in no way constitutes a scientific setting to rest of concerns over the latter issue. Empirical results seeming to show that the items of the PCL-R are multidimensional could be entertained as calling into question the construct validity of the scale as a measure of psychopathy. In the first place, the construct of psychopathy has traditionally been considered to be dimensional and unitary (e.g., Neumann, Hare, and Newman, 2007a). However, for two reasons, it is the putative multidimensionality which should be most concerning. It is apparent that, in the estimation of many, the major difficulty posed by this state of affairs is simply the absence of a consensus on an issue central to an accounting of the PCL-R's psychometric characteristics. It seems the only thing upon which there is agreement is that the PCL-R does not have a unidimensional structure. Employing, almost exclusively, variants of linear factor- and principal component- analytic methodology (exploratory and confirmatory hierarchical, correlated factor, and bifactor with and without testlets or parceling, etc.), psychopathy researchers have proposed, to date, a considerable diversity of structures, estimated at 11 or more (Pérez, Herrero, Velasco, and Rodriguez-Díaz, 2015). Test analytic work on the scale has spawned not only multifarious conclusions about its structure, but, also, as a byproduct, long-standing and, at times, acrimonious disputation on the issue.

From a test standards perspective, it is somewhat difficult to reconcile this widespread employment with the contentiousness surrounding current understanding of the PCL-R's psychometric behaviour. International surveys of forensic mental health professionals indicate that the PCL-R is among the tests most commonly used to assess violence risk. Facilitated by authorized translations into dozens of different languages, it has been adopted for use by correctional and forensic psychiatric agencies around the world.

Since an account of the development of the original version was first published in a journal article >35 years ago (Hare, 1980), the scale has come to be employed widely in both clinical and research settings.

The Hare Psychopathy Checklist-Revised (PCL-R Hare, 1991, Hare, 2003) is a 20-item expert observer rating scale of psychopathic (antisocial, dissocial) personality disorder. Empirical support for this position is provided by a small-scale dimensionality analysis informed by the UMLV sense of unidimensionality. A reconsideration of the scale's theoretical structure singles out the unidimensional monotone latent variable (UMLV) brand of unidimensionality as the one appropriate to the role of grounding dimensionality assessments of the PCL-R. Herein, we argue that the purported multidimensionality might, in actuality, be an artifact of the grounding of dimensionality assessment on species of dimensionality- those specific to principal component and linear factor analysis- which are incongruous with the scale. In the second, unidimensionality is the sole psychometric justification for employing a composite of test items to scale individuals. In the first place, because the construct of psychopathy has traditionally been considered to be dimensional and unitary, results seeming to show that the PCL-R is multidimensional could be taken as calling into question the construct validity of the scale as a measure of psychopathy. The implications of multidimensionality for the scale are nontrivial. Investigation into the structure of Hare's Psychopathy Checklist-Revised (PCL-R) has consistently shown it to be multidimensional.

Hare psychopathy checklist