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September 20, 2007
Effectiveness of London's Cameras for Solving Crimes
From Schneier on Security linking to thisislondon.co.uk:
Some politicians in the UK analyzed the number of cameras in particular areas and compared that with the proportion of the crimes solved. They found that police "are no more likely to catch offenders in areas with hundreds of cameras than in those with hardly any."
I agree with the many people who noted flaws in the logic and data with this argument. However, I am glad that there are people asking these kinds of questions. Maybe as cameras spread to the US, there will be more American data on the effectiveness of cameras.
Some interesting statistics from the article:
There are now 10,524 CCTV cameras in 32 London boroughs funded with Home Office grants totalling about £200million.
Wandsworth has 993 cameras, Tower Hamlets, 824, Greenwich, 747 and Lewisham 730, but police in all four boroughs fail to reach the average 21 per cent crime clear-up rate for London.
By contrast, boroughs such as Kensington and Chelsea, Sutton and Waltham Forest have fewer than 100 cameras each yet they still have clear-up rates of around 20 per cent.
Quotes from comments on Schneier's blog on the flaws with the study:
To show that cameras do not help, you need to compare statistics for the same place before and after cameras were introduced. The article compares the resolution of crimes in areas differing concentrations of cameras to a mythical "average crime solving rate". Since crime is known to vary strongly by area anyway, the conclusions are void.
what is it that makes those areas have more cameras?
what are the crimes in the different areas, are the crimes different between the areas of high and low surveillance?
Do the introduction of cameras change the type of crime. Are there trends of crime changing as more cameras are introduced.
Percentages are one thing but what are the actual figures.
And glaringly missing are the figures over time. ie How do the percentages of solved crimes change as more cameras are introduced. Did they stay the same even when more cameras where introduced.
What are the national averages of solving crimes for all the particular crimes in each area.
Posted by rshah at September 20, 2007 10:33 PM
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