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Tuesday, 23 February 2010

Cycles and Rhythms of Policing

My colleague at the Centre for Advanced Spatial Analysis (CASA) at University College London (UCL), Fabian Neuhaus is interested in the cycles and rhythms of life - see his blog UrbanTick here.

Policing has cycles and rhythms which can clearly be seen in the plotting of CAD incidents over time. Just to show you that these are not unique to the borough I am studying now I have compared it with the first borough I analysed on this blog; this is borough A. The present borough is Borough B. Both are inner-London boroughs. The data for Borough A is April 2007 to March 2008, Borough B the complete year of 2009.

The point I am making with the top graph is the similarity in call volume profile of the two boroughs across a 24 hour period. The second to top graph shows the same thing but this time just using "I" calls to show a similar call profile; and because I only use "I" calls in the subsequent graphs.

The third graph I find slightly humorous having worked on and managed response teams. I have only included "I" calls that have had five or more units assigned to them. Usually the most serious calls. What I find humorous is the obvious dip in such calls between 1700hrs and 1900hrs and less obvious but detectable, between 0900hrs and 1100hrs. This is of course when the meal breaks for police officers occur which means there are less officers to attend calls.

The fourth graph shows that the rhythms occur, with subtle differences over the week days.

The fifth graph I have thrown in to show that there is also variation in this data. This shows the months of year split into days of the week. There are indication of seasonal variations - more calls in the summer and perhaps the influence of events, for instance sporting events, in May.

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