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Abstract |
The major systematic review on street lighting and crime, Home Office Research Study 251, suggests that claims for the effectiveness of lighting against crime are justified. The review at first sight appears to be an appropriate statistical synthesis of all studies on street lighting and crime across the world. However on close examination, the statistical claims and methods are unfounded. In three cases examined there is a clear conflict between the evidence and the reviewers' interpretation of this. One of the principal problems is easily seen. The time-series of the original data from the Bristol study shows no good evidence for the crime reduction benefit of lighting. However the review gives the result for the same data as being extremely statistically significant. It is suggested that such a difference between the newly lit and the control areas occurring purely by chance is less than one in a billion, but this is manifestly wrong. Two other component studies, Birmingham and Dudley, are examined. |
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