Outdoor Lighting and Crime - Amper

If there is some substance to the belief that more and brighter outdoor lighting would help
reduce actual crime, then extending the belief to its ultimate stage means there should be little
or no crime in the bright outdoor lighting conditions of daytime, but that is far from the facts.
For example, 54% of violent crime in the USA occurred between 6 am and 6 pm, and only
20% of rapes involve unknown assailants at night (BJS 1999). Only 35% of all burglaries in
the USA are reported to have occurred at night, or 48% of all burglaries for which the time of
occurrence is known (UCR 1996). Note that these figures are for all reported crime in the
whole of the USA, which gives them substantial face validity. In England and Wales, crime
survey results indicated that nearly two-thirds of the total of assaults, burglaries, robberies,
thefts and vandalism occurred after dark (Ramsay and Newton 1991, ONS 2000). An
unresolved issue is the extent to which the proportion of crime at night is influenced by
effects of light at night rather than by other factors such as the available amount of leisure
time at night.
Effects of light on actual crime have been investigated with field studies, but extraneous
influences have often confounded the results. Crime-reducing, nil, uncertain, and crimeincreasing
effects of light at night have variously been reported for night or day or both.
Thorough scientific reviews published in 1977 and 1997 in the USA concluded that the effect
of lighting on actual crime was unknown. Nevertheless, crime prevention specialists and
some academics have asserted that lighting is important, at least in some circumstances, in the
fight against crime. Recent UK findings of beneficial effects of brighter lighting have
bolstered this view despite complaints, by others, of procedural and analytical shortcomings
in the studies.
Part 1 indicates that, in general, lighting and crime experiments have not been planned and
executed well enough for the results to be considered reliable. There is evidence of
systematic bias towards a beneficial effect of lighting on crime. Industry and company
funding is known to be associated with an unjustifiable excess of findings beneficial to the
industry or company concerned. In some or even the majority of cases, areas with
substantially elevated crime incidence (crime hotspots) have been chosen for experimental
treatment. Regardless of how ineffectual the treatment might be, reduced crime afterwards
relative to control areas is naturally more likely and the increased lighting tends to get the
credit for the beneficial result. Pooling results to get apparently greater precision and
reliability does not eliminate such systematic bias. Results obtained by an instance of this
method were shown to be improbably large, given the possibility that the experimental
treatment could be repeated many times, with claimed crime reductions for each treatment
compounding to values far lower than have ever been observed. The main conclusion of Part
1 is that increased outdoor lighting has not been shown to have a reliably beneficial effect in
reducing crime.
Marchant (2003) examined the statistical methods used in the Dudley and Stoke-on-Trent
lighting and crime experiments and in the meta-analysis described in Part 1. He found
several errors that were serious enough for the conclusions of these studies to be rejected.
This is independent support for the writer’s findings about these studies, and it strengthens the
case that the main conclusion of Part 1 is correct.
Strident campaigns based on the apparently erroneous results have encouraged public lighting
projects for crime prevention in the last few years, especially in the UK. Street crime in the
UK rose by 28% in the year ending in April 2002 (Hoge 2002).
2