Whether you attend, whether you contribute, whether you learn and pick up stuff in the program itself are the sorts of things the people running the programs will be measuring. Much of that is the kind of acquisition of knowledge and information, becoming more educated and having an understanding and taking pride in graduating from the program.
Within prison, as you've implied, there are a number of drivers that may be good or may be about gaming the system. It may be about if I do the right courses and show I've done these things it will improve my chance of release. The proof of that pudding is what happens in the community when re-exposure emerges again and how the work that has started within the prison, because it doesn't finish there.... You do the program, but then it is how you implement that, how that gets translated into real world experience that is crucially important. We know that from residential and community drug and alcohol work. We know that in terms of mental health in-patient treatments, community-based treatment. It's all very well to get the learning and understanding within one venue. It is your capacity to translate that learning into the new one that is where the rubber hits the road, and that's where you need high-quality community reintegration, supervision, and follow-up to ensure success. That's really the only place in which you can tell that it's worked or not, and that means measuring abstinence.