Crime and the Depenalization of Cannabis Possession: Evidence from a Policing Experiment * We evaluate the impact on crime of a localized policing experiment that depenalized the possession of small quantities of cannabis in the London borough of Lambeth. Such a policy can: (i) impact the demand for cannabis in Lambeth as users move there to purchase cannabis; (ii) enable the Lambeth police to reallocate effort towards other types of crime. We investigate whether the depenalization policy impacts the level and composition of crime, using administrative records on criminal offences by drug type, and for seven types of nondrug crime. We find that depenalization in Lambeth led to significant increases in cannabis possession offences that persisted well after the policy experiment ended. We find evidence that the policy caused the police to reallocate effort towards crimes related to the supply of Class-A drugs, as well as reallocating effort towards non-drug crime: there are significant reductions in five types of non-drug crime, and significant improvements in police effectiveness against such crimes as measured by arrest and clear-up rates. Despite the overall fall in crime attributable to the policy, we find the total welfare of local residents likely fell, as measured by house prices. These welfare losses are concentrated in Lambeth zip codes where the illicit drug market was most active. Finally, we shed light on what would be the impacts on crime of a citywide depenalization policy, by developing and calibrating a structural model of the market for cannabis and crime, accounting for the behavior of police and cannabis users. This highlights that many of the gains of the policy can be retained, and some of the deleterious consequences ameliorated, if all jurisdictions depenalized cannabis possession. These results provide new insights for the current policy debate on the regulation of illicit drug markets.

The recently introduced national pupil database in England allows the tracking of every child through the compulsory phases of the state education system. The data from key stage 2 for three local education authorities are studied, following cohorts of pupils through their schooling. The mobility of pupils among schools is studied in detail by using multiple-membership multilevel models that include prior achievement and other predictors and the results are compared with traditional 'value-added' approaches that ignore pupil mobility. The analysis also includes a cross-classification of junior and infant schools attended. The results suggest that some existing conclusions about schooling effects may need to be revised. Copyright 2007 Royal Statistical Society.

We investigate possible explanations for the educational gender gap at age 16. We employ a national dataset of matched exam results of the cohort of pupils who took Key Stage 3 tests in 1999 and GCSEs in 2001. Our key result is the sheer consistency of the gender gap, across both the attainment and the ability distribution, with regard to both raw outcomes and value added. It is primarily driven by performance differentials in English. The generality of the gender gap suggests its source is not within-school practice, which means that policy directed at improving such practice may be misplaced.

Standard-Nutzungsbedingungen:Die Dokumente auf EconStor dürfen zu eigenen wissenschaftlichen Zwecken und zum Privatgebrauch gespeichert und kopiert werden.Sie dürfen die Dokumente nicht für öffentliche oder kommerzielle Zwecke vervielfältigen, öffentlich ausstellen, öffentlich zugänglich machen, vertreiben oder anderweitig nutzen.Sofern die Verfasser die Dokumente unter Open-Content-Lizenzen (insbesondere CC-Lizenzen) zur Verfügung gestellt haben sollten, gelten abweichend von diesen Nutzungsbedingungen die in der dort genannten Lizenz gewährten Nutzungsrechte. Abstract Basic methods to compute the required sample size are well understood and supported by widely available software. However, the sophistication of the sample size methods commonly used has not kept pace with the complexity of the experimental designs most often employed in practice. In this paper, we compile available methods for sample size calculations for continuous and binary outcomes with and without covariates, for both clustered and non-clustered RCTs. Formulae for panel data and for unbalanced designs (where there are different numbers of treatment and control observations) are also provided. The paper includes three extensions: (1) methods to optimize the sample when costs constraints are binding, (2) simulation methods to compute the power of a complex design, and (3) methods to consider in the sample size calculation adjustments for multiple testing. The paper is provided together with spreadsheets and STATA code to implement the methods discussed. Terms of use: Documents in

A vast literature uses ingroup biases to explain animus towards others. The notion can be extended to multi-identity societies, where social preferences are de…ned over one ingroup and multiple outgroups. We use a novel research design to recover the structure of social preferences across outgroups in a high stakes setting. We investigate whether increased animosity towards Muslims post 9-11 had spillover e¤ects on Black and Hispanic individuals in the federal criminal justice system. Using linked administrative data tracking defendants from arrest through to sentencing, we …nd that as 9-11 increased animosity towards Muslims, sentence and pre-sentence outcomes for Hispanic defendants signi…cantly worsened. Outcomes for Black defendants were unchanged. We underpin a causal interpretation of our …ndings by providing evidence to support the identifying assumptions underlying the research design. The …ndings are consistent with judges and prosecutors displaying social preferences characterized by contagious animosity from Muslims to Hispanics. To understand why increased animosity towards Muslims post 9-11 could spillover onto Hispanics, we draw on work in sociology to detail how Islamophobia and immigration have become intertwined in American consciousness since the mid 1990s, but were forcefully framed together in the aftermath of 9-11. We narrow the interpretation of the results as being driven by social preference structures using decomposition analysis, and correlating sentencing di¤erentials to judge characteristics, including their race/ethnicity. Our …ndings provide among the …rst …eld evidence of contagious animosity, so that social preferences across outgroups are interlinked and malleable.