Comments on: Mapping Crime in Oxford Over Time

By: Ian Turton

Ian Turton — Sat, 15 Aug 2009 20:59:52 +0000

So did you allow for the background population or not? unless you link to your methods it looks like a pretty coloured map with no scientific value like all the other crime maps out there. Have a look at chapter 2 (the one I wrote with Stan Openshaw) and then decide if your map mean anything.

By: Ian

Ian — Sat, 15 Aug 2009 12:37:29 +0000

Thanks for the interest in the crime map – I led the project at Cimex. Re: “this is an example of people who donâ€™t know what they are doing not bothering to read the literature”:

We worked closely with Spencer Chainey on this project (Chapter 5 of the book you recommend – Director of Geographical Information Science at the Jill Dando Institute of Crime Science, University College London) and the various local services in Oxford. All our data processing and map based presentation techniques (using geocoded source data) were approved by University College. The important thing here was to make the content accessible to broader public audience and to compliment the stories on the associated TV show and the feedback we received form user testing was this did succeed.

By: Ian Turton

Ian Turton — Thu, 13 Aug 2009 18:23:26 +0000

As with so much of the current NeoGeography we are seeing these days this is an example of people who don’t know what they are doing not bothering to read the literature and use existing techniques that the PaleoGeographers solved in the early 1990′s.

Check out http://books.google.com/books?.....38;f=false for example.

Ian

By: David Lamb

David Lamb — Thu, 13 Aug 2009 00:25:22 +0000

I don’t know how heat maps are generally constructed, but suspect it is based on kernel density techniques. This technique would require geocoding all the crimes, and choosing a bandwidth that would determine how many of those points would influence the resulting density value. The bandwidth can really toy with how the overall density surface looks. As has been explained to me, data like this would probably benefit more from a variable bandwidth technique which might help with the underlying population density (as mentioned by srboisvert).

This book explains it better than I could: http://www.spatialanalysisonli.....nsity.html

By: Jo Jordan

Jo Jordan — Wed, 12 Aug 2009 19:13:47 +0000

The trouble is there is so much crime there that the whole map is covered. Lol! Must remember that when I go there next.

By: srboisvert

srboisvert — Wed, 12 Aug 2009 11:53:40 +0000

I’ve gotten maps like this from my local police force. The problem is that they tend to actually be maps of population density. With a comparable crime rate a higher density area – with apartment buildings – always looks like a it has a greater crime problem.