From February 1999 to January 2001, a study was conducted in South Australia and Western Australia on 200 male offenders, mainly prisoners with convictions for violent offences. The aim was to determine what changes in the experience and expression of anger had occurred, before and after they participated in an anger management intervention.
These results were compared to a control group of offenders, who had been selected for intervention but had not yet received the program (waiting-list controls). The treated group showed very small improvements.
University of Sydney
Criminal rehabilitation
Statistical Thinking
- What questions do you have about the trial?
Study Design
Statistical Thinking
What is a randomized controlled double-blind study? Why is it good but rare?
Randomized controlled double-blind study
- Investigators obtain a representative sample of subjects.
- Investigators randomly allocate the subjects into a Treatment Group and a Control Group.
- The Control Group is given a placebo, but neither the subjects nor the investigators know the identity of the 2 groups (double-blind).
- Investigators compare the responses of the 2 groups.
- The design is good because we expect the 2 groups to be similar, hence any difference in the responses is likely to be caused by the treatment.
Homework
- How many phases of clinical trials are there?
- For which of these phases would double blind methods be most important?