Effects of closed versus open groups on attrition and recidivism outcomes for sex offenders in custody-based treatment programmes

ABSTRACT There is growing recognition for the importance of group processes in treatment for sexual and other offenders. However, there is little evidence about the influence of programmming factors that affect the composition of groups, including use of closed or open groups. The current study examined how group format was associated with programme attrition and reoffending outcomes for sex offenders attending custody-based treatment programmes. Cohorts of offenders who attended a programme as it transitioned from a closed group format to an open group format were compared to cohorts of offenders in a second programme that remained in closed group format over the study period (n = 490). We found that post-intervention cohorts in both programmes showed reductions in rates of programme non-completion which were not significantly associated with group format. Group format was not a significant predictor of reoffending outcomes. The results suggest that both open and closed groups may be viable alternatives for achieving treatment outcomes in intensive sex offender programmes.