Source: (2002) In, Measuring the Impact of Imprisonment: papers from a roundtable held in London on 9 November 2001. London: International Centre for Prison Studies. Kings College. Pp. 17-21.While various models for the nature and purpose of prison have come and gone over the years, Stephen Duguid writes that the public has retained a common sense view that prisons ought to deter people from further crime or even persuade or enable them to choose other vocations after release. He notes that, in line with this, there are signs that prison systems are again showing interest in rehabilitation and reduction in recidivism as a measure of their success. Against this background, Duguid reflects on the use of recidivism data in evaluating the effectiveness of prison programs.