Planning to Evaluate a Sex Offender Treatment Program/Strategy? What Are Some Challenges?

Concerns about reoffending and requirements to respond in the same way to all sex offenders can make it difficult to determine what approaches are effective for sex offenders.

Concerns about reoffending by sex offenders may make the use of a control group unacceptable. When ethical and legal issues make it difficult to conduct experimental evaluations of sex offender programs that include random assignment to a treatment group or a control group that receives no specialized treatment, evaluators can use other methods to establish comparison groups. For instance, sex offenders can be assigned to either a treatment group receiving the treatment of interest or a comparison group receiving some other method of treatment.

When legislation or other requirements call for all sex offenders to be dealt with in the same manner, such as registering upon release from prison, it can be hard to assess the impact of an approach. One way to address this is to compare sex offenders released prior to the enactment of the new legislation to those released after the enactment of the new legislation. Another option is to conduct cross-jurisdictional evaluations; studies can compare offenders in jurisdictions with different requirements or methods of dealing with sex offenders, for example.

Attrition from treatment by high-risk sex offenders is particularly problematic.

Sex offender programs generally have a high percentage of sex offenders who do not complete treatment. The offenders at highest risk are also those most likely to drop out or be expelled from treatment. Evaluations in which large numbers of high-risk offenders have dropped out of treatment must account for attrition or risk biasing the findings toward those who do complete treatment.

Low base rates of reoffending and small sample sizes make it difficult to determine program effectiveness.

Official recidivism data indicate that relative to the reoffense rate for other offenders, sex offenders are less likely to commit new sex offenses. Low base rates of recidivism for sex offenders may make it difficult to find long-term treatment benefits in follow-up studies. In addition, sex offender outcome studies have often had small sample sizes (200 participants or fewer). One way to address this is to have a larger sample size to study sex offenders than one would ordinarily use for recidivism studies or to conduct meta-analyses of several studies with small sample sizes.

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