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Monday, 7 February 2011

London Wards December 2010 crime and disorder clustered, classified and mapped

Over the weekend I have been trying to improve on my the map in my last post from a London perspective. London was clustered in a group that I classified as having robbery and burglary problems due to where the cluster centres were for that group. In fact London does have robbery problem according to the figures that were used in the K-means clustering method but the burglary figures showed that London had a burglary problem that was about average. It was the small force of Bedfordshire that was clustered with London that does have a big burglary problem and a also a robbery problem that pushed the centre of the cluster in the direction of burglary.

I have used the same methodology as in the last post to create a classification for London shown above but without dividing numbers by police officers and staff numbers. I have excluded three Wards, Heathrow Villages, St James and West End for two reasons.
  •  St James and West End Wards are not shown in the published tables, they are split into eight sub-wards with no information about their locations.
  • Heathrow Village is Heathrow Airport that clustered uniquely unsurprisingly, St James and West End always cluster together with a far higher crime rate than any other wards. Removing these gives a better scale to the other Wards.
I have been experimenting using the December 2010 crime statistics shown on the official Metropolitan Police website to split up the other crime category into, criminal damage, drugs, theft, etc. The problem with doing this is that it decreases the weighting of the burglary, robbery, etc crimes and ASB in relation to the other crime category. To me the choice of restricted crime categories and ASB reflects the importance of these crimes are to the police and the public. By keeping to those categories and weighting them equally in my clustering I do not have justify anything. Soon as I start making my own selections I have to justify my choices.

Back to the map. In broad terms it shows what I expected. There are a couple of surprises,
  • the location of the boroughs showing robbery problems, though having checked these do include personal and business robberies; my previous analysis has been exclusively on personal robbery.
  • the variation in vehicle crime numbers.
It has to be borne in mind that December 2010 was an unusual month with the heavy snowfalls. I need to analyse few more month to see how stable this classification is.

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