To Determine if Changing to White Light Street Lamps Reduces Crime: A Multilevel Longitudinal Analysis of Crime Occurrence during the Relighting of Leeds, a UK City

Abstract

This confirmatory study estimates the effect on Police Recorded Crimes (PRCs) of a relighting programme that installed nearly 80,000 white-light lamps, replacing predominantly orange ones, in the years 2005 to 2013, throughout the UK city of Leeds. Time series of weekly PRCs in all 107 Middle-layer Super Output Areas, while road lighting was being almost completely relit, were analysed using multilevel modelling. The background change in PRCs in each area, when and where no lighting was changed, was separated from that associated with when and where replacement white lamps were installed, by including a polynomial for the underlying time-trend. The key interest is how the replacement by new white lamps affects the rate of crime, from the start to the finish of the relighting. The results show that over the period, there was an estimated 2% rise in daylight adjusted darkness crime associated with relighting, 95% confidence interval (CI) (−3% to +7%). Similarly associated with relighting, (unadjusted) darkness crime showed a rise of 3%, 95% CI (−1% to +8%) and the round-the-clock measure of crime (the sum of darkness and daylight crime) gave an estimated rise of 3%, 95% CI (0% to +6%). Many checks were made, all giving consistent null results; that is, giving narrow confidence intervals around zero of only a few percent wide after relighting. Therefore, no evidence was found for an improvement (or detriment) in the city’s level of crime by relighting, contrary to the substantial reduction anticipated by the city council.