Objectives

To determine whether the use and display of license plate readers (LPRs) enhance the crime prevention effects of police patrol, particularly by increasing initial and residual deterrence from patrol presence.

Methods

Crime hot spots in a large suburban jurisdiction were randomly assigned to receive intermittent patrols (15–30 min each) by officers with or without LPRs on their vehicles for 4.5 months. Data on 785 patrols at 33 hot spots were used to compare initial and residual outcomes of LPR and non-LPR patrols. Outcomes analyzed for each patrol visit via chi-square tests, survival analyses, and/or logistic regression included the following: the likelihood of a vehicle recovery or arrest; the likelihood of a new crime or disorder call in the location while the officer was present (measuring initial deterrence); time until a new crime or disorder call following the officer’s departure (measuring residual deterrence); and first type of call (crime or disorder) following the officer’s departure (measuring residual deterrence).

Results

LPR use increased stolen vehicle recoveries but not arrests. LPR use did not reduce the likelihood of a new call in the hot spot while an officer was present, nor did it affect the timing or seriousness of the next call following a patrol.

Conclusions

This study provides little clear evidence for the crime prevention efficacy of using LPRs in general patrol, which is a common practice in the USA. Police and researchers should give more attention to testing the relative benefits of different LPR uses and modes of deployment.

中文翻译：

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车牌阅读器是否增强了警察巡逻的初始和剩余威慑作用？准随机检验

目标

确定使用和显示车牌阅读器（LPR）是否增强了警察巡逻的预防犯罪效果，特别是通过增加巡逻人员的初始威慑力和残余威慑力。

方法

大型郊区辖区的犯罪热点被随机分配接受间歇性巡逻（每次巡逻15-30分钟），这些巡逻人员的车上有或没有LPR，为期4.5个月。使用33个热点处785个巡逻的数据来比较LPR和非LPR巡逻的初始结果和剩余结果。通过卡方检验，生存分析和/或逻辑回归分析的每次巡逻访问的结果包括：车辆恢复或逮捕的可能性；该人员在场时在该地点再次发出犯罪或骚扰电话的可能性（测量初始威慑力）；该人员离职后直至再次接到新的犯罪或骚扰电话的时间（测量剩余威慑力）；人员离开后的第一类呼叫（犯罪或混乱）（测量剩余威慑力）。

结果

使用LPR可以增加失窃车辆的追回率，但不会增加逮捕的风险。LPR的使用并没有减少在警员在场时在热点再次打出电话的可能性，也不会影响巡逻后下一次打入电话的时间或严重性。

结论

这项研究几乎没有明确证据表明在美国常规巡逻中使用LPR可以达到预防犯罪的功效。警察和研究人员应更加注意测试不同LPR用途和部署模式的相对优势。