Prospective crime mapping in operational context Final report

Figure A3.1: Changes in the spatial distribution of risk following the introduction of the pilotIt is important to bear in mind that this is a purely visual and descriptive analysis. Moreover, thepatterns are relative and do not necessarily indicate where the risk of burglary was greatest, but justwhere it changed the most. Nevertheless, what Figure A3.1 does illustrate is that risk moves evenwhen considered over fairly lengthy intervals of time, such as seven months. This mobility of risk isone of the underpinning justifications of Promap.With respect to statistical significance, an analytic approach worthy of discussion has been developedby Ratcliffe (2005). The aim of this is to detect changes in the spatial placement of crime over timewithin a particular area, such as a BCU. Using a Monte-Carlo simulation, the spatial patternsobserved can be compared against the null hypothesis that any changes observed could haveoccurred on the basis of chance. Consequently, the test developed provides an inferential statisticaltest of the visual analysis presented in Figure A3.1.88