crime reduction interventions

Research methods for evaluating crime reduction interventions

The question relates to how we may go about evaluating crime reduction interventions. 
For example, probation is a crime reduction intervention, but does it work? How can we answer that question? Should we look at statistics? What are the advantages and disadvantages of looking at statistics. Should we interview probation officers? Should we interview offenders who are on probation? Should we interview offenders who have completed a sentence on probation? What are the advantages and disadvantages of these methods.
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