The experimental design of this study used a waiting-list control group. This control group was made up of offenders who went through pre-program assessment, but were then randomly assigned to the program waiting list. All offenders in the sample were subject to at least 12 months follow-up after release. Statistical controls were used to correct for the possible effects of these differences. This high recidivism rate illustrates the relatively high-risk nature of the sample offenders.
Cognitive skills training generally targets offenders at high risk of recidivism.
The reduction in reconvictions was even greater. However, statistical controls indicate that these effects were reduced when differences in the criminal history variables for the two groups were accounted for. These numbers also suggest that offenders who started but did not complete the program had higher recidivism rates than those who did. The dropouts simply may have been higher-risk offenders. About two thirds of the dropouts withdrew for reasons such as lack of interest or disruptive behaviour.