Prospective crime mapping in operational context Final report

More documents

Recommendations

Info

Figure 2.6: Nearest neighbour index: retrospective and prospective methods0.60.5nearest neighbour index0.40.30.20.1retrospectiveprospective01 9 17 25 33 41 49 57 65 73 81 89 97k-orderThe results of the nearest neighbour analysis suggest that the prospective method generateshotspots that are perhaps of more practical use than their retrospective equivalents, in thatthey yield more burglary risk per distance moved for patrolling officers.Shift by shift analysisA still further development of the system would be to generate predictions that were specificto particular police shifts. Recorded crime data are imperfect for this purpose, since theyretain a degree of uncertainty about the precise time of an event, but within the limits of thedata to hand, knowing how crime patterns vary by shift offers a clear operational benefit.Otherwise, a forecast for the day would represent the average pattern over the three shifts,but fail to represent the actual geographical patterns for any individual shift. Simpson’sparadox emerges again! To illustrate, consider two areas, A and B. Area A has a high crimerisk during the morning and evening, whereas area B has its highest risk during the afternoon.If one takes the average risks across the two areas, area A would be identified as having thegreater overall risk. However, during the afternoon it would be area B to which operationalresources would most profitably be deployed. The importance of this effect depends upon anumber of factors, one of which is the particular operational tactics to be deployed. Wherehigh visibility policing is used, or temporary measures are implemented with celerity, it iscrucial to know how crime problems move over the course of the day. If longer term crimeprevention interventions are deployed, the highest implementation dosage would be directedto the areas that have the overall highest risks. The point can be made the other way round.Between-shift differences in presenting crime problems should be one factor in determiningthe balance between short-term and long-term interventions.To summarise the story so far:1. the effects identified in Promap are robust, occurring with slight variation across allthe areas studied;2. exploring the relationships closely offers a route forward to refining and optimisingPromap;3. the basic instrument could be developed to meet the tailored needs of a willing policearea.27
3. Tactical options and selecting a pilot siteIn this section there will be a discussion of process by which a pilot area was chosen.Additionally, consideration is given to the types of tactical option that might be usefullyemployed alongside the system developed. The reason for this was that the success of anycrime reduction strategy is contingent upon the identification of the right tactical options thatwill trigger the relevant crime reduction mechanisms (e.g. Tilley, 1993). In the current project,which places its emphasis on the application of a predictive mapping system updatedroutinely, consideration of a number of factors is required. At the time of the research, thefollowing section was produced to provide a number of tactical options that could be usedoperationally to realise the advantages which may accrue from use of the Promap technique.Since the Promap exercise currently concentrates on the crime of domestic burglary(although it has wider potential applicability) so too do the tactical options. It is important tosay that despite this exercise the authors deferred to the policing craft of the operationalofficers who used Promap. The attempt here is simply to make available their current thinkingon tactical implications based on the literature on effective crime reduction.To provide a context for the review that follows, similarities and differences among the threepolice BCUs that were selected as potential pilot sites for the study will be outlined. Followingfrom this, a matrix of a number of tactical options, constructed from evidence of what works,will be discussed. The matrix also provides some guidance on the agencies that are in alllikelihood most suitably placed to implement the different options at the local level. This will befollowed by a discussion of a number of novel possible tactics. Finally, the area andtimescales for the delivery of these tactics will be mentioned emphasising the necessarymechanisms needed to reduce burglary.Potential pilot sitesTo identify a suitable pilot site researchers visited three areas during the first quarter of 2005to gain an in-depth knowledge of how each dealt from day to day with its problem ofresidential burglary from both analytical and operational perspectives. Visits took place overten weeks and involved meetings with key officers as well as attendance at tasking and coordinationmeetings for each of the areas. The three sites visited were Corby andWellingborough in the Northamptonshire force area and, ‘A’ Division in DerbyshireConstabulary. Table 3.1 provides a comparison of the areas and summarises some of themain points for each.All three areas were National Intelligence Model (NIM) compliant and tasking and coordinationis thus organised in a similar way. ‘A’ Division is much larger than either Corby orWellingborough Sectors, comprising an entire BCU, and had a much higher volume ofdomestic burglary. Intelligence is disseminated in a similar fashion across the three areas andall analysts were capable of producing crime point maps using a GIS, and did so fortnightly.None of the analysts in any of the areas routinely (if at all) generated retrospective hotspotmaps of the kind discussed in the previous chapter. All three areas have gazetteers that cangeocode data. This is done only when a map is produced. The geocoding process itselfappeared to be quick in all areas. However if the datum was not assigned a postcode (as isthe case in about 10% of crimes), geocoding was manual and hence time-consuming. Whileeach area had a different crime recording system, ‘A’ Division incorporated the most recentdata as its system was updated every twenty-four hours.28
Page 2 and 3: 1. UCL JILL DANDO INSTITUTE OF CRIM
Page 4 and 5: ContentsAcknowledgementsExecutive s
Page 6 and 7: 2.5 Illustration of a simple neares
Page 8 and 9: Project outcomesPatterns of burglar
Page 10 and 11: those that involved collaboration w
Page 12 and 13: 1. IntroductionThis report represen
Page 14 and 15: optimally calibrated system, the go
Page 16 and 17: e ij = n .j x n i.nWhere, e ij is t
Page 18 and 19: Table 2.2: Knox ratios for Mansfiel
Page 20 and 21: Table 2.6: Monte-Carlo results for
Page 22 and 23: Table 2.10: Weekly Knox ratios for
Page 24 and 25: Table 2.14: Monte-Carlo results for
Page 26 and 27: Figure 2.1: The five policing areas
Page 28 and 29: The results for area 5 again demons
Page 30 and 31: The bandwidth used to generate the
Page 32: a densely populated urban area this
Page 35 and 36: Table 2.24: Average number of crime
Page 37: Patrolling efficiencyAs discussed e
Page 41 and 42: Selecting a pilot siteThe decision
Page 43 and 44: Table 3.2: Tactical options matrixT
Page 45 and 46: Type ofinterventionStudyUse ofintel
Page 47 and 48: Other potential tactical optionsAt
Page 49 and 50: 4. System development and evolution
Page 51 and 52: the same time of day as each other
Page 53 and 54: unfortunately, implementation or us
Page 55 and 56: any tactical options were employed
Page 57 and 58: the end of the pilot. In addition t
Page 59 and 60: Figure 5.1: Promap dissemination pr
Page 61 and 62: the busy schedule of the new Divisi
Page 63 and 64: Tactical deliveryCommand Team daily
Page 65 and 66: Table 5.3: Number of respondents wh
Page 67 and 68: permitted, up to four plain clothed
Page 69 and 70: observation made by those who used
Page 71 and 72: A simple time-series analysis (see
Page 73 and 74: Two approaches were used to compute
Page 75 and 76: Figure 6.3: Changes in the proporti
Page 77 and 78: Figure 6.5: Changes in the proporti
Page 79 and 80: With respect to implementation real
Page 81 and 82: ReferencesAggresti, A. (1996) An In
Page 83 and 84: Johnson, S.D., Summers, L., and Pea
Page 85 and 86: Appendix 1. The information technol
Page 87 and 88: Figure A1.2: Stand-alone applicatio
Page 89 and 90:
Recommendations that may be realise
Page 91 and 92:
Section 1: knowledge and understand
Page 93 and 94:
Extra Comments (please outline any
Page 95 and 96:
In relation to the evaluation of in
Page 97 and 98:
Time-series analysisFor the purpose
Page 99 and 100:
Figure A3.1: Changes in the spatial
Page 101 and 102:
Figure A3.2: Lorenz curves showing
Page 103 and 104:
To recapitulate and elaborate, the
Page 105 and 106:
Concluding comments on methodThe te
Page 107 and 108:
Figure A5.2: An enlargement of the
Page 109 and 110:
Figure A5.6: Prospective map magnif
Page 111:
Produced by the Research Developmen
show all

Prospective crime mapping in operational context Final report

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?