Prospective crime mapping in operational context Final report

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Table 2.10: Weekly Knox ratios for Ashfield (values in bold are statistically significantaccording to the residual scores (not shown), N=1012)WEEKS1 2 3 4 5 6 7 8 9 10 11 12100 1.61 1.44 1.28 1.22 1.06 1.02 0.96 0.96 0.96 0.97 0.97 0.97200 1.46 1.29 1.25 1.18 1.08 1.00 0.99 0.99 0.98 1.01 0.94 0.93300 1.43 1.39 1.23 1.17 1.08 1.05 0.99 0.98 0.94 0.97 0.95 1.00400 1.20 1.16 1.15 1.12 1.08 1.06 1.00 0.96 0.96 0.95 0.95 0.98500 1.13 1.10 1.05 1.03 1.00 0.99 0.97 1.01 1.02 0.96 0.97 0.96600 1.20 1.16 1.13 1.09 1.07 1.05 1.01 1.04 1.04 1.04 1.04 1.05700 1.35 1.20 1.16 1.13 1.06 1.02 1.01 0.96 0.96 0.99 1.01 1.04800 1.06 1.03 1.04 1.00 0.98 0.96 0.97 0.97 0.98 1.01 1.02 1.05900 0.96 0.98 0.97 0.97 0.96 0.91 0.90 0.94 0.96 1.00 1.08 1.121000 0.93 0.96 0.97 0.96 0.99 0.99 1.00 1.03 1.03 1.06 1.03 1.06Corby Police SectorFor Corby, the most recent data available at the time of analysis covered the period January-December 2003. There were only 429 burglaries for this period in Corby. The results, shownas Tables 2.11 and 2.12, are again very consistent. Unlike the above analyses, while moreburglaries occur within 100m and one month of each other than would be expected on thebasis of chance, the difference is not statistically reliable. However, this may be due to thelow sample size (e.g. the expected cell count for that cell was five times lower than the samecell for Mansfield), particularly for that cell, rather than reflecting an irregularity in the patternof the communicability of risk. As with the analyses for Mansfield the analyses suggest thatthe risk of burglary communicates over a distance of up to 700m and endures for one month,although houses within 401-500m appear not to be at significantly heightened risk.Table 2.11: Knox ratios for Corby (values in bold are statistically significant accordingto the residual scores (not shown), N=429)MONTHS1 2 3 4 5 6100 1.17 1.07 1.11 1.02 1.06 0.87200 1.20 0.99 1.22 1.02 0.89 0.96300 1.13 0.94 0.90 1.12 0.96 0.92400 1.22 1.01 1.02 1.05 1.10 0.96500 1.04 1.04 1.02 1.09 1.09 1.03600 1.11 1.08 1.11 1.02 1.02 1.02700 1.12 1.01 1.11 0.91 0.98 1.03800 1.02 1.06 1.07 0.98 1.13 1.06900 1.02 1.04 1.05 1.03 0.93 1.111000 1.10 0.91 1.09 1.03 1.06 1.06As with the results for Mansfield, the Monte-Carlo analysis suggests that around 20 per centmore burglaries occurred within 101-200m and one month of a burgled home. Alsoconsistent with the findings for Mansfield, the risk to houses within 401-500m of burgledproperties appears to be elevated yet non-significant.For completeness, an additional Knox analysis was conducted to examine the temporal trendin more detail. However, as this analysis generated a larger number of cells than the monthlyanalysis and there was such a low volume of crime for this area, the results were consideredunreliable and will not be discussed further. Because of the essential similarity of the data11
across areas it is thought likely that the same patterns underlie the Corby data, andapplication of predictive mapping in low crime areas is by no means regarded as unprofitable.Table 2.12: Monte-Carlo results for Corby (values in bold are statistically significant,N=429)MONTHS1 2 3 4 5 6100 1.18 1.02 1.12 1.02 1.09 0.87200 1.20 0.96 1.23 1.03 0.88 0.96300 1.13 0.93 0.86 1.16 0.91 0.96400 1.22 1.03 1.04 1.07 1.09 0.96500 1.04 1.04 1.04 1.07 1.05 1.10600 1.11 1.12 1.08 1.01 1.04 1.00700 1.12 1.03 1.07 0.93 0.99 1.03800 1.02 1.07 1.06 1.02 1.14 1.07900 1.03 1.07 1.08 1.02 0.97 1.101000 1.09 0.92 1.09 1.04 1.06 1.06Alfreton ‘A’ DivisionFor ‘A’ Division in Derbyshire, the period for which the most recent data were available at thetime of analysis was April 2003-March 2004. There were 1,703 burglaries during this period.More recent data are now available but were not used for the analyses in this section of thereport. Tables 2.13 and 2.14 show the Knox and Monte-Carlo analyses. A similar patternemerges to those presented above, although the risk appears to communicate over a greaterdistance than for the other areas. Thus, the results suggest an elevated risk to those up to900m from burgled homes for around one month.Table 2.13: Knox ratios for ‘A’ Division (values in bold are statistically significantaccording to the residual scores (not shown), N=1703)MONTHS1 2 3 4 5 6100 1.37 0.93 0.91 0.93 0.85 0.76200 1.29 0.93 0.91 0.93 0.93 0.96300 1.19 1.00 0.94 0.94 0.83 0.90400 1.17 0.97 0.99 0.94 0.85 0.91500 1.08 0.95 0.91 0.98 0.85 1.02600 1.09 1.02 0.95 0.95 0.89 0.95700 1.07 1.00 0.95 0.95 0.88 1.07800 1.06 1.02 0.94 0.98 0.98 0.95900 1.16 1.03 0.97 0.91 0.93 0.891000 1.04 1.03 0.99 1.01 0.86 0.94As with the other analyses, the Knox ratios shown in Table 13.2 demonstrate a pattern ofdistance decay. That is, the risk of burglary is greatest nearest to burgled homes, after whichit remains elevated but clearly diminishes. Expressed in a slightly different way, just under 40per cent more burglaries occurred within 100m and one month of each other than would beexpected on the basis of chance. This is the highest concentration observed for that cellacross the data sets analysed. In contrast, around eight per cent more burglaries occurredbetween 400-800m and one month of each other than would be expected.12
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 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 and 38: Patrolling efficiencyAs discussed e
Page 39 and 40: 3. Tactical options and selecting a
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
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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
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Figure A1.2: Stand-alone applicatio
Page 89 and 90:
Recommendations that may be realise
Page 91 and 92:
Section 1: knowledge and understand
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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
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To recapitulate and elaborate, the
Page 105 and 106:
Concluding comments on methodThe te
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Figure A5.2: An enlargement of the
Page 109 and 110:
Figure A5.6: Prospective map magnif
Page 111:
Produced by the Research Developmen
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Prospective crime mapping in operational context Final report

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