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A theory of offending

Australian Institute of Criminology, John MacLeod
22 March 2005 -

Dr John MacLeod
Research Development and Statistics Directorate, Home Office, United Kingdom


Dr MacLeod's analysis is based on several cohort samples drawn from the Offenders Index, a database of all standard list (more serious) convictions in England and Wales from 1963 to the present. The analysis has identified distinct groups of offenders. The characteristics of these groups can be accurately modelled using a relatively simple mathematical formulation. This mathematical model is consistent with a theory of criminal careers in which offending is a Poisson process with constant rate and constant probability of desistance after conviction. Dr MacLeod's theory challenges the conventional wisdom of criminal careers and provides a theoretical explanation for the age crime curve in which age is not a causal factor. The theory has been used to construct forecasting models for prison and probation services and in the identification of persistent offenders.

Dr John MacLeod has worked in the various research departments of the Home Office for the past 30 years, initially as an Operational Researcher, and from the mid 1980s also as a Criminologist. He has undertaken research on tape recording police interviews with suspects, police activity analysis, performance measurement and more recently in various aspects of criminal careers research. His first degree is in mathematics, statistics and computer science. Mid-career, he completed a M.Phil. and Ph.D in Criminology at the Institute of Criminology, Cambridge. He is a Fellow of the Institute of Mathematics and its Applications and a member of the British Society of Criminology.

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