Portal de Periódicos da CAPES

PROTOCOL: Increased Police Patrol Presence Effects on Crime and Disorder

2016; The Campbell Collaboration; Volume: 12; Issue: 1 Linguagem: Inglês

10.1002/cl2.159

1891-1803

Cody W. Telep, David Weisburd, Sean Wire, David P. Farrington,

Policing Practices and Perceptions

Campbell Systematic ReviewsVolume 12, Issue 1 p. 1-35 PROTOCOLOpen Access PROTOCOL: Increased Police Patrol Presence Effects on Crime and Disorder Cody W. Telep, Cody W. TelepLead Reviewer: Cody W. Telep, Ph.D. School of Criminology and Criminal Justice Arizona State University 411 N. Central Avenue, Suite 600 Phoenix, AZ 85004 USA Phone: 602.496.1295 Fax: 602.496.2366 Email: cody.telep@asu.eduSearch for more papers by this authorDavid Weisburd, David WeisburdSearch for more papers by this authorSean Wire, Sean WireSearch for more papers by this authorDavid Farrington, David FarringtonSearch for more papers by this author Cody W. Telep, Cody W. TelepLead Reviewer: Cody W. Telep, Ph.D. School of Criminology and Criminal Justice Arizona State University 411 N. Central Avenue, Suite 600 Phoenix, AZ 85004 USA Phone: 602.496.1295 Fax: 602.496.2366 Email: cody.telep@asu.eduSearch for more papers by this authorDavid Weisburd, David WeisburdSearch for more papers by this authorSean Wire, Sean WireSearch for more papers by this authorDavid Farrington, David FarringtonSearch for more papers by this author First published: 01 July 2016 https://doi.org/10.1002/CL2.159 AboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat 2. BACKGROUND FOR THE REVIEW Patrol is typically the largest function in police agencies around the world, and the majority of officers tend to be assigned to general service duties (Bayley, 1992). Patrol officers generally spend their time responding to emergency calls for service from the public, deterring crime through their presence, and carrying out special assignments from supervisors. In recent years, it has become increasingly recognized that police agencies can have a beneficial impact on crime and disorder (Lum, Koper, & Telep, 2011; National Research Council, 2004; Telep & Weisburd, 2012; Weisburd & Eck, 2004). Police patrol officers have likely played a major role in police efforts to effectively address crime as these officers make up a substantial portion of police resources and are on the front lines responding to crime and citizen concerns on a daily basis. An important question is the extent to which increased police presence through increased police patrols impact crime and disorder. If police can deter crime through their presence, does increasing the quantity of this presence help reduce crime and disorder? Being present, of course, is not the only activity patrol officers engage in, but it a major component of patrol and one that is important to examine systematically because agencies around the world devote such extensive resources to police patrol. Our review follows the definition of "police patrol" from Kelling et al. (1974: 2) in the Kansas City preventive patrol study (see below): "to most, police patrol is equated with the visible presence of a police officer in the community, whether on foot or in a marked automobile." Thus, for our purposes, presence is the key component of patrol. We can also think of patrol work as generally falling into one of two broad categories: "answering assigned calls and conducting general surveillance" (Whitaker, 1982: 13). We are especially interested in the second category because the police have greater control over the time devoted to non-call presence and the ability to increase (or decrease) it. As we discuss below, this "general surveillance" can take on different forms with varying levels of focus. We recognize this is a simplification of the complex multitude of activities that fall under patrol work. But this categorization helps make clear what is and is not within the scope of this review, as we emphasize below in our summary of the theory and prior research guiding our inclusion criteria. Not all forms of police being physically present in an area qualify as patrol presence. The concept of "general surveillance" emphasizes a crime prevention focus through police visibility. This is different than officers being present to deliver a program in schools or attend a community meeting. Our emphasis is on the role of patrol presence for immediate crime prevention purposes. Based on the deterrence literature, crime should be reduced if police patrol can effectively increase the certainty that criminal activity will be observed and punished. One mainstay of policing since the 1930s has been random preventive patrol by automobile. Random patrol generally involves officers randomly driving around their beat or assigned area in downtime between calls for service (see Kelling & Moore, 1988). While preventive patrol has traditionally been allocated in beats or precincts, its proponents have emphasized the importance of providing the widest possible geographic coverage (Reppetto, 1976). The idea is to create a sense of omnipresence and to maximize deterrence by keeping offenders on their toes about when an officer will drive by next (see Kelling et al., 1974). This effort to create ambiguity in the minds of offenders about when police presence will next occur is supported by recent work in the deterrence literature. Loughran and colleagues (2011: 1056) emphasize the potential benefits of changing levels of patrol, noting "With the same amount of resources, an alteration of police policy by manipulating the ambiguity of the certainty of arrest would enable them to enhance the deterrent effect they have. Our finding with respect to ambiguity suggests it would be worthwhile for law enforcement to exploit any vagueness in perceptions of the risk of punishment." Loughran et al.'s (2011) recommendations are particularly relevant to hot spots policing (see below), but the ideas would apply to larger areas as well if the police are present with enough frequency to create ambiguity in the minds of offenders as to when the next period of presence will occur. Additionally, crime is expected to be deterred at the time officers are driving through (or sitting in) a particular area, because the certainty of punishment is highest when officers can physically view any crime or disorder activity. Durlauf and Nagin (2011) also argue that the certainty of punishment is key to understanding the deterrent effects of police patrol. Nagin (2013) expands on this argument, noting that the police role as "sentinel" or guardian is central to a deterrence regime. If the number of police or their targeting of offenders can be heightened to a significant degree than significant crime prevention benefits are likely to be gained: "increasing the visibility of the police by hiring more officers and by allocating existing officers in ways that heighten the perceived risk of apprehension consistently seem to have substantial marginal deterrent effects" (Durlauf & Nagin, 2011: 14). The importance of police as guardians relates to the arguments in routine activities theory (Cohen & Felson, 1979). Cohen and Felson (1979) argue that crime occurs when a motivated offender and suitable target come together in space and time in the absence of capable guardianship. Police are the best example of formal guardianship that can ideally disrupt the opportunities that could lead to criminal events. Thus, even if the number of motivated offenders and suitable targets remain constant, if police can increase their levels of capable guardianship at places, then crime could potentially be reduced. Increasing police presence can occur in a number of ways. As noted above, a common method dating back to the 1930s is changing levels of random patrols in beats or neighborhoods. We note here that our focus in this review is not on the effectiveness of random patrol per se, but rather the effectiveness of increasing police presence. Thus, we begin our review of the literature with a discussion of random preventive patrol both because it has traditionally been a common police presence allocation method and because increasing (or decreasing) levels of random patrol has been the subject of some prior research (see below). In the major study in this area, the Kansas City Preventive Patrol Experiment (Kelling et al., 1974)5 increasing (or decreasing) levels of preventive patrol did not have a significant impact on crime or victimization. In the Kansas City study, 15 beats in the South District were assigned to one of three conditions. In the five control beats, preventive patrol was left at the normal level of one car per beat. In the five reactive beats, preventive patrol was totally eliminated. Officers still responded to 911 calls in these beats but were instructed to not randomly patrol these areas between calls. In the five proactive beats, random patrol was increased with two or three cars assigned to each beat, thus doubling or tripling the amount of random preventive patrol. The results called into doubt the effectiveness of random patrol as a crime prevention tool. There were no significant differences across the groups in reported crime, arrests, and levels of reported victimization. The conventional wisdom after the Kansas City study was that random patrol did not work and that increasing or decreasing police presence would not impact crime rates (see Bayley, 1994; Weisburd & Eck, 2004). Gottfredson and Hirschi (1990: 270), for example, argued that, "no evidence exists that augmentation of police forces or equipment, differential patrol strategies, or differential intensities of surveillance have an effect on crime rates." Subsequent research examining the concentration of crime at place also called into question the logic behind random preventive patrol. Because crime is not randomly distributed across beats, but is instead highly concentrated (e.g., see Sherman, Gartin, & Buerger, 1989; Weisburd, Groff, & Yang, 2012), randomly allocating patrol resources does not seem to be the most efficient or effective way to control and prevent crime (see Telep & Weisburd, 2012). These findings on the high levels of concentration of crime at place helped influence the hot spots policing model of increased presence discussed more below. Despite these concerns with the logic underlying the approach, random preventive patrol is routinely dismissed as an ineffective strategy that police should not be using based largely on the results of just the Kansas City study. But as Sherman and Weisburd (1995) note, the small sample of beats in the study and the low base rates for many crimes created low statistical power, which made it difficult for the evaluation to discern a significant difference between the study groups even if one had existed (see also Sherman, 1992). Larson (1975) also notes that the patrol levels across the groups may not have been as different as intended, in part because officers were entering the reactive beats frequently to respond to calls for service. Other studies examining beat-based patrol increases found more positive results in terms of crime reduction (e.g., see Press, 1971; Schnelle et al., 1977), although these studies also suffered from methodological flaws. A more systematic examination of the impact of increasing patrol in beats or large geographic areas may thus provide a stronger answer to the question of "does random preventive patrol work?" than simply citing the Kansas City study as the final answer (see Sherman, 2013). In a recent review of systematic reviews in policing, Telep and Weisburd (2016) argued that while most police innovations in policing (see Weisburd & Braga, 2006) have been covered by an existing review, more traditional tactics in policing have received less attention. While these "standard model" tactics (Weisburd & Eck, 2004) such as random preventive patrol are generally seen as outdated, they continue to occupy a substantial portion of police time and resources and so more systematic inquiry into their effects would be worthwhile. This is not to necessarily suggest that additional studies collected in this review will demonstrate that random preventive patrol is a highly effective approach. But it also seems imprudent to argue that a tactic is ineffective largely based on the results of a single study that suffers from issues of methodology and statistical power. A systematic review offers an opportunity to carefully assess the existing evidence base for random preventive patrol and other methods of increasing police presence. Increasing police presence is not limited to random patrols at the beat level. Increasing preventive police patrols has also been an important component in a number of interventions at smaller units of geography than the police beat. Many of these interventions have focused on crime hot spots. Crime hot spots are small units of geography with high rates of criminal activity. The specific geographic area that makes up a hot spot varies across studies, ranging from individual addresses or buildings (e.g., Sherman et al., 1989) to single street segments (i.e. both sides of a street from intersection to intersection; e.g., Sherman & Weisburd, 1995) to small groups of street segments with similar crime problems such as a drug market (e.g., Weisburd et al., 2006). As noted above, because crime is so highly concentrated, the hottest spots in a city, regardless of the specific unit of analysis chosen, are responsible for a large chunk of a jurisdiction's crime problem. The concentration of crime at place has become well established through research over the last two decades. From Sherman et al.'s (1989) groundbreaking finding that 3.5 percent of addresses in Minneapolis included 50 percent of crime calls to the police (see also Pierce, Spaar, & Briggs, 1988), to more recent work by Weisburd and colleagues in multiple cities that shows that just five percent of street segments produce 50 percent of the crime each year (Weisburd et al., 2004; Weisburd, Telep & Lawton, 2014; Weisburd & Amram, 2014; Weisburd et al., 2012), there is growing consensus that crime is highly concentrated at small micro geographic units in cities. Indeed, Weisburd et al. (2012) argue that we have to recognize a "law of crime concentrations at places." Hot spots policing, also sometimes referred to as place-based policing (see Weisburd, 2008), covers a range of police responses that all share in common a focus of resources on the locations where crime is highly concentrated. The original hot spots policing experiment in Minneapolis (Sherman & Weisburd, 1995) focused on trying to increase patrol levels on high crime street blocks up to three hours per day. Sherman and Weisburd (1995) used computerized mapping of crime calls to identify 110 hot spots of roughly street-block length. Police patrol was doubled on average for the experimental sites over a 10-month period. Officers in Minneapolis were not given specific instructions on what activities to engage in while present in hot spots. They simply were told to increase patrol time in the treatment hot spots. The study found that the experimental as compared with the control hot spots experienced statistically significant reductions in crime calls and observed disorder. More recently, additional rigorous studies have focused on increasing police patrol presence in high crime or at risk places. The Sacramento Police Department, for example, used 15 minute stops by officers in a random order to increase police presence on high crime street segments (Telep, Mitchell, & Weisburd, 2014). The study was guided by recommendations by Sherman (1990) and Koper (1995) to deliver police presence in medium-length doses in an unpredictable order to maximize the deterrent effect of the police. In Sacramento, the approach was successful as treatment group hot spots had significantly fewer calls for service and Part I crime incidents than control group hot spots when comparing the three month period of the experiment in 2011 to the same period in 2010. Ratcliffe and colleagues (2011) evaluated the impact of using foot patrol to increase patrol levels in high crime areas in Philadelphia. Results suggested significant declines in violence in the treatment hot spots compared to the control sites. The intervention was particularly effective for hot spots that reached a threshold of violence (i.e. the hottest hot spots). Other presence-based hot spots studies include Di Telia and Schargrodsky's (2004) evaluation of the impact of adding police officers to guard Jewish and Muslim buildings following a terrorist attack in Buenos Aires, and Taylor, Koper, and Woods' (2011) analysis of the impact of increased presence in lengthy crackdowns in high crime locations in Jacksonville, FL. These hot spots or micro place interventions generally show stronger evidence of effectiveness, in part because police are maximizing their deterrent ability by focusing in on the highest crime places. Hot spots are much smaller than the police beats and neighborhoods used in many interventions designed to increase random patrols, but the logic here is similar. The goals of hot spots interventions focused on increasing police presence are to both deter criminal activity and increase levels of guardianship. As Koper (1995) argues, the deterrent ability of the police is likely enhanced in these smaller units, because potential offenders are more likely to see police and be aware of their increased presence. In reviewing the evidence on police presence, Nagin (2013) finds overall support for using increased presence in small geographic units to reduce crime. He argues "The evidence is clear that large changes in police presence do affect crime rates. The change in presence may be the result of an unplanned event, such a terror alert that triggers a large increase in police officers in public spaces, or it may be a strategic response to a known crime problem, such as in hot spots policing deployments. In either case, crime rates are reduced in places where police presence has been materially increased" (Nagin, 2013: 42). Not all hot spots policing studies, however, focus exclusively on increasing police presence. Indeed, a number of different approaches can be taken to dealing with crime hot spots, including nuisance abatement programs (e.g., Mazerolle, Price, & Roehl, 2000), problem-oriented policing (e.g., Braga et al., 1999; Weisburd & Green, 1995), and drug house raids (e.g., Sherman & Rogan, 1995). We are not including studies examining these other approaches to dealing with high crime places. We recognize that these other types of interventions may also involve increases in police presence. Nonetheless, in an effort to avoid problems of disentangling the effects of multiple treatments simultaneously (e.g., the SARA model of problem-oriented policing vs. increased presence), we will focus only on those hot spots studies focused entirely (or almost entirely) on increasing police presence. We also recognize that this will still lead to some overlap with the studies included in the hot spots policing systematic review by Braga, Papachristos, and Hureau (2012). Any hot spots interventions focused on the strategies listed above or other strategies not related to simply increasing police presence will not be covered by our review and as a result, we do not expect the overlap between the two reviews to be substantial. Additionally, as we noted above and discuss below, we also expect our group of eligible studies to include non-hot spots studies focused on increasing police presence in larger geographic areas, such as beats. In their moderator analysis, Braga and colleagues (2012) found that hot spots studies focused on increased police presence had a significant impact on reducing crime and disorder, although the magnitude of this impact was less than that of problem-oriented hot spots studies. As we describe below, we will code any activities that study authors note that police engaged in while increasing patrols, but the primary focus of the program must be to simply increase police presence and not to engage in any particular problem solving or enforcement activity. Moderator analyses in this review will hopefully allow for comparisons of increased police presence in beat-based random patrol vs. hot spots policing, an important comparison for examining the relative benefit of adopting hot spots policing over a more standard patrol model. This will ideally provide important new insights to the evidence base on patrol strategies because, to date, there has been no direct comparison of random patrol to other patrol approaches like hot spots policing (Sherman, 2013).1 We suspect that many police interventions examining increased patrol and/or presence will focus on either the police beat or a micro place (e.g., hot spot) as the unit of analysis, although police could increase patrol levels at any unit of geography from very small (e.g., a particular school or interaction) to very large (e.g., an entire jurisdiction). Our main requirements (discussed below) are that the increase in police presence be the focus of the intervention and that the evaluation examine crime and disorder outcomes using a rigorous research design. Just as the unit of analysis for interventions that increase police presence can vary, so can the dosage or intensity of increased police presence. Dosage and intensity can be assessed by examining both the number of extra officers added to each geographic unit and the amount of time these extra officers are spending in the unit relative to comparison sites. These levels can vary considerably from study to study and could include, for example, having an extra patrol car conducting random patrols in a beat 24 hours a day (e.g., the proactive beats in Kelling et al., 1974), having a single officer present in a hot spot 24 hours a day (e.g., Lawton, Taylor, & Luongo, 2005) or having a crackdown team of multiple officers present in a hot spot for a few hours at a time (e.g., Taylor et al., 2011). To the extent possible based on information provided by authors, we will code the dosage (number of officers) and intensity level (amount of time spent) for each eligible study. We will not limit our review to any particular dosage or intensity level as long as treatment sites are receiving increased patrol compared to control sites. We plan to use a similar coding scheme regardless of the geographic unit in which the police presence occurs. To the extent possible based on information provided in eligible studies, we will note the number of extra officers and/or patrol cars added to the intervention site (whether that be a hot spot, police beat, or some other unit) and the amount of time these officers were spending each day in the designated intervention site. Finally, in any sort of place-based police intervention, there is a risk that police actions will shift crime or disorder to other places where programs are not in place. This phenomenon is usually termed displacement, and it has been a major reason for traditional skepticism about the overall crime prevention benefits of place-based prevention efforts (see Reppetto, 1976). The assumption that displacement is an inevitable outcome of focused crime prevention efforts though has been replaced by a new assumption that displacement is seldom total and often inconsequential (see Weisburd et al., 2006). Displacement in place-based police interventions at both the micro-level (Bowers et al., 2011) and the meso-level (Telep et al., 2016) have been the focus of prior systematic reviews and both of these reviews find more evidence for a "diffusion of crime control benefits" (Clarke & Weisburd, 1994) to areas nearby than for displacement. We will collect and code data on displacement in our eligible studies (see below), but suspect our findings will be in line with these two prior Campbell reviews focused specifically on the topic. 3. OBJECTIVES OF THE REVIEW The objective of this systematic review is to synthesize the extant empirical evidence (published and unpublished) on the effects of increased police patrol presence on crime and disorder. Specifically, this review will seek to answer the following questions: 1. How does increased police patrol presence affect crime and disorder? 2. Do crime and disorder effects vary based on the intensity of the police intervention? 3. Do crime and disorder effects vary based on the geographic unit of analysis for the police intervention (e.g., hot spots vs. police beats)? 4. Do the effects of police patrol presence vary by the types of crimes examined? 5. Do different types of police patrol have differential influences on crime and disorder (e.g., foot patrol vs. motorized patrol)? 4. METHODOLOGY 4.1 Criteria for inclusion and exclusion of studies in the review The eligibility criteria are as follows: Population. Studies must involve geographic areas of a city or other jurisdiction as the unit of analysis. There must be at least one geographic area of the jurisdiction designated as the treatment/intervention area. There is no limit to the number of treatment/intervention sites in a particular jurisdiction. Intervention. The intervention must be an instance of a police or law enforcement agency increasing police patrol presence in a specified geographic area in an attempt to address crime and/or disorder. Thus, we are not interested in the effectiveness of a particular strategy or tactic per se. The intervention must involve increasing patrol resources in a specified geographic area. The geographic area is not restricted to a particular size and could include (but is not limited to) street segments, police beats, or neighborhoods. The police intervention must be limited to (or focused almost entirely on) increasing the amount of time officers are spending in the geographic area for the purpose of immediate crime prevention. For example, a hot spots intervention focused entirely on increasing officer time in the hot spots would be included, while a problem-oriented hot spots approach would not. We will code any activities police are engaged in during times of increased patrols. Data on these activities may include, for example, information on arrests made, citations written, and pedestrian or vehicle stops made. To be eligible, the intervention must be focused primarily on increasing police presence and not on any particular enforcement activity or other strategy (e.g., problem solving, zero tolerance arrests). Comparator conditions: A study must include a control/comparison group that did not receive the intervention. The group must be of the same geographic size as the target area (e.g., comparing a treatment beat to a comparison beat). In other words, we will not include designs in which a target beat, neighborhood, etc. is compared to the rest of the jurisdiction. Outcomes: The study must examine at least one crime or disorder related outcome. This could include measures related to total crime or disorder or total amount of a particular crime or disorder type. Most studies will likely use official police department data to measure crime outcomes, typically data from citizen calls for service or incident reports. Some studies may use victimization data collected from interviews or surveys to measure crime outcomes. Disorder outcomes will usually be measured from some combination of calls for service, incident reports, and researcher observations of physical and social disorder. Designs: A study much be a true experiment (randomized controlled trial) or a quasi-experiment with a comparison group Exclusion criteria We will exclude any studies that do not include a comparison group and only assess the impact of police presence on crime by examining outcomes before and after an intervention (pre-post studies) because of our concerns about the internal validity of these studies. Because we want to ensure we are capturing all relevant studies of the impact of increased police presence, we will collect pre-post studies, but will not include these studies in our main analysis. We may decide to conduct a separate examination of these pre-post studies depending on the number of studies we identify. We will not exclude studies on the basis of language or geographical location. Limited resources do not allow us to search in languages other than English, but we will obtain and translate non-English language studies with English abstracts or keywords that are identified in our search. 4.2 Search strategy for identification of relevant studies Several strategies will be used to perform an exhaustive search for literature fitting the eligibility criteria. First, a keyword search will be performed on an array of online abstract databases (see lists of keywords and databases below). Second, we will review the bibliographies of past reviews of police presence.2 Third, we will perform forward searches for works that have cited seminal studies on increasing police presence.3 Fourth, we will review the tables of contents of leading journals in the field to ensure our searches have not missed relevant articles.4 Fifth, we will search the publications of several research and professional agencies (see list below). Sixth, after finishing the above searches and reviewing the studies as described later, we will e-mail the list to leading scholars knowledgeable in the area of police presence. These scholars will be defined as those who authored a study that appears on our inclusion list. This is likely to identify additional studies, as these experts may be able to refer us to studies we may have missed, part