Objectives

This study examines the effect Project Green Light Detroit (PGLD), an integrated CCTV program, on crime at commercial and non-commercial city parcels in Detroit, MI.

Methods

A quasi-experimental design was used by implementing a difference-in-differences model with adjustments made for variation in treatment timing and treatment heterogeneity.

Results

Findings from the study indicate that PGLD increased reporting of property crimes at some participating locations but did not significantly impact violent or disorder crimes. Most of the impact of PGLD was attributable to locations that joined the program early in its implementation.

Conclusions

Studies examining treatment effects that are implemented over time should adjust for variation in treatment timing and treatment heterogeneity. Several new statistical methods exist that can implement these in a variety of software packages.

中文翻译：

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评估治疗异质性下的因果效应：对底特律闭路电视节目的评估

目标

本研究考察了底特律绿灯计划 (PGLD) 项目（一个综合闭路电视节目）对密歇根州底特律商业和非商业城市地块犯罪的影响。

方法

通过实施差异中的差异模型，使用准实验设计，并针对治疗时间和治疗异质性的变化进行调整。

结果

研究结果表明，PGLD 增加了一些参与地点的财产犯罪报告，但并未显着影响暴力或混乱犯罪。PGLD 的大部分影响归因于在项目实施早期加入该项目的地点。

结论

检查随时间实施的治疗效果的研究应根据治疗时间和治疗异质性的变化进行调整。有几种新的统计方法可以在各种软件包中实现这些方法。