The development of Integrated Offender Management (IOM) approaches have spread rapidly across England and Wales since 2009 when IOM was acknowledged by Government through the Home Office policy statement. The MoJ commissioned process evaluation of the five IOM pioneer sites (Senior et al 2011) found that assessing the impact and benefits of IOM was difficult given the definitional issues of IOM and problems in identifying additionality. To date, this remains a challenge for local agencies, despite attempts to facilitate this, such as the IOM efficiency toolkit (Home Office and MoJ 2011).
This paper will examine the challenges and limitations of the methodologies employed and will identify what lessons can be learned for evaluating other criminal justice initiatives such as Payment by Results schemes where definitions of interventions and additionality may be difficult to determine.