Thursday, July 12, 2012

60 Steps Revisited: Step 23 - Diagnose Your Hot Spot

Back in 2009, I did a series of posts covering the excellent book Crime Analysis For Problem Solvers. The book is published by the US DOJ's Problem Oriented Policing Center (POP Center). Because of the value I think this book has for crime analysts, and policing in general, I am going to re-post this series on here on the blog.

I know that it's been a while since I posted in my series covering Crime Analysis For Problem Solvers. Now that the holidays are over and we're all back in the office regularly, it's time to look atStep 23 - Diagnose Your Hot Spot. With the increase in mapping capabilities in law enforcement software packages, there is an increase in these programs offering "Hot Spot" tools to designate a geographic location as a "hot spot" based on crime data. But what is a "hot spot" and why are they important?

The authors of Crime Analysis For Problem Solvers define three different types of Hot Spots.
  • Hot dots are locations with high crime levels. These show crime concentrated at facilities or at addresses of repeat victims (see Steps 28 and 29). Multiple crime events at places are represented by dots.
  • Hot lines are street segments where crime is concentrated. These might occur, for example, if vehicles parked along particular streets suffer high rates of break-ins. Multiple crimes along street segments are shown with lines.
  • Hot areas are neighborhoods where crime is concentrated. Hot areas arise for a variety or reasons. Area characteristics may give rise to crime. Or a hot area may contain many separate and discrete problems. On maps, hot areas are shown as shaded areas, contour lines, or gradients depicting crime levels.
Geospatial analysis to identify Hot Spots will help you in identifying problematic areas. In my workflow, after I pull Calls and Offense data from our records management system and into our GIS, I'll then run these crime layers through CrimeStat, a spatial statistics analysis tool, to create additional Hot Spot layers for my crime maps.

Running a Hot Spot tool to identify Hot Spots on a map should not be the end of your analysis. Just knowing that there is a problem in a particular geographic location is not enough. This is alluded to in this chapter by the authors who conclude the chapter with this:
Hot spot analysis can be a valuable tool early in the problem-solving process, but having discovered hot spots, you need to ask why some spots are hot and others are not. Stopping analysis after the discovery of hot spots can result in superficial analysis and the implementation of ineffective responses. If there is no geographical component to the problem, hot spot mapping has little utility and you must use other analytical approaches.
Hot Spot analysis identifies geographic areas that need further analysis to identify specific problems and develop solutions to those problems. However, it's not the end of your analysis but instead it's just a beginning.

Next time, we'll cover Step 24 - Know When To Use High-Definition Maps.

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