“…Moderating variables commonly suggested to account for the inconsistent performance of instruments across studies are inter rater agreement, missing values, sample selection bias, and widely differing outcome measures (e.g., in terms of the duration of follow-up periods, official vs. unofficial sources utilized, incon sistent definitions for recidivism; see, e.g., Craig, Beech, & Browne, 2006;Falshaw, Bastes, Patel, Corbett, & Friendship, 2003;Hanson, 2002;Marshall & Barbaree, 1988). Although sam ple selection and outcome measures can be put on the same metric by studying the performance of alternative instruments in the same sample (Hanson & Morton-Bourgon, 2009;Langton et al, 2007; and the present study), this does not hold for the issues of interrater agreement and missing values.…”