Scores from the Psychopathy Checklist–Revised (PCL-R) are used to support decisions regarding personal liberty. In our study, performed in an applied forensic psychiatric setting, intraclass correlation coefficients (ICC) for absolute agreement, single rater (ICCA1) were .89 for the total score, .82 for Factor 1, .88 for Factor 2, and .78 to .86 for the four facets. These results stand in contrast to lower reliabilities found in a majority of field studies. Disagreement among raters made a low contribution (0%-5%) to variability of scores on the total score, factor, and facet level. For individual items, ICCA1 varied from .38 to .94, with >.80 for seven of the 20 items. Items 17 (“Many short-term marital relationships”) and 19 (“Revocation of conditional release”) showed very low reliabilities (.38 and .43, respectively). The importance of knowledge about factors that can affect scoring of forensic instruments (e.g., education, training, experience, motivation, raters’ personality, and quality of file data) is emphasized.

Anna M. Dåderman, Åke Hellström
Criminal Justice and Behavior, January 9, 2018