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Estimating the Risk of Reoffending by using Exponential Mixture Models
Author(s) -
Copas J. B.,
Heydari F.
Publication year - 1997
Publication title -
journal of the royal statistical society: series a (statistics in society)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.103
H-Index - 84
eISSN - 1467-985X
pISSN - 0964-1998
DOI - 10.1111/1467-985x.00059
Subject(s) - prison , conviction , sample (material) , statistics , recidivism , psychology , computer science , actuarial science , econometrics , mathematics , criminology , law , economics , political science , chemistry , chromatography
In deciding whether to release a prisoner on parole, the Parole Board is provided with a statistical score which estimates the chance that the prisoner will reoffend within the period of time that he or she would otherwise be in prison. This score is based on a survival analysis of data on a sample of releases from long‐term prison sentences. To capture most reoffences which occur within 2 years of release, follow‐up must continue for at least 3 years to allow for the delay between offence and conviction. We reanalyse the data by using a model which explicitly allows for this delay. The new analysis can be applied to data with a substantially shorter length of follow‐up. This means that risk scores can be constructed from more up‐to‐date data and at less cost.