Although a large number of offenders are released to parole each year, little is known about the effectiveness of parole supervision in reducing re-offending. The few studies that have been conducted provide mixed results and, for the most part, have been unable to rule out the possibility of selection bias. The present study is the first to evaluate the effectiveness of parole supervision using propensity score matching techniques. It compares two groups of offenders, carefully matched in terms of factors likely to affect re-offending but differing in terms of whether they are supervised. The results suggest that parole supervision does reduce the risk of re-offending.
For time series of count data, correlated measurements, clustering as well as excessive zeros occur simultaneously in biomedical applications. Ignoring such effects might contribute to misleading treatment outcomes. A generalized mixture Poisson geometric process (GMPGP) model and a zero-altered mixture Poisson geometric process (ZMPGP) model are developed from the geometric process model, which was originally developed for modelling positive continuous data and was extended to handle count data. These models are motivated by evaluating the trend development of new tumour counts for bladder cancer patients as well as by identifying useful covariates which affect the count level. The models are implemented using Bayesian method with Markov chain Monte Carlo (MCMC) algorithms and are assessed using deviance information criterion (DIC).
PurposeThe purpose of this paper is to determine whether trends in arrests for heroin, amphetamine‐type substances (ATS) and cocaine can be used as indicators of trends in the use of these drugs.Design/methodology/approachThe question was addressed using ARIMA models to analyse the relationship between arrests and emergency department (ED) admissions for narcotics, amphetamine type substances (ATS) and cocaine.FindingsStrong positive correlations were found for the narcotics and cocaine series between arrests and EDs in the same month (contemporaneous correlation) and between arrests in the current month and overdoses in earlier months (lagged correlation). The contemporaneous correlation between ATS arrests and EDs was slightly less strong than the lagged correlations at two and four months. A jump in ATS EDs, was followed by a jump in arrests in the same month and then two and four months later.Practical implicationsArrests for narcotics use/possession, ATS use/possession and cocaine use/possession may in some circumstances provide useful intelligence about drug trends and/or a basis for evaluating the impact of police drug law enforcement activity on the use of narcotics, ATS and cocaine when other stronger measures of drug use are not available.Originality/valueEfforts to evaluate local drug law enforcement activity on illicit drug use have been hampered by poor measures of trends in illicit drug use at small area levels. This is the only study the authors are aware of that has examined the long‐term relationship between illicit drug arrests and emergency department admissions for illicit drug use.
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