A study of recidivism rates found that prisoners who participated in educational programs returned to prison at half the rate of non-participants. Critics noted that program participants volunteered—they may have been more motivated to change than non-participants from the start. A randomized trial would better isolate the program's true effect, but ethical concerns limit such experimental designs in prison settings.
The passage suggests that
educational programs definitely cause reduced recidivism
motivation has no influence on rehabilitation outcomes
randomized trials have no ethical constraints
self-selection into programs can complicate interpretation of their effectiveness
Correct Answer: D
Choice D is the best answer. Volunteer bias makes it hard to know if the program or pre-existing motivation caused results.
- Context clues: Volunteers "may have been more motivated...from the start."
- Meaning: Self-selection introduces an alternative explanation for outcomes.
- Verify: The call for randomized trials shows the selection issue is a real methodological problem.
đź’ˇ Strategy: When participants choose to participate, infer possible selection bias.
Choice A is incorrect because the selection effect creates doubt about causation. Choice B is incorrect because motivation is suggested as an alternative explanation. Choice C is incorrect because "ethical concerns limit such experimental designs."