outdoor lighting and crime, part 1 - Astronomical Society of Victoria

guidelines it is up to authors to decide whether to mention potential sources of bias. In this
case, its non-mention does not seem justified, particularly in view of the unpalatably large
effects of financial and nonfinancial conflicts of interest that have been described recently in
leading scientific journals (see Section 2.1 above.)
5.5.2 Measure of effect
The odds ratio used by Farrington and Welsh (2002a,b) seems to be inverse of that required.
It most directly represents a change in crime in the control area relative to the experimental
area, which is not the most convenient arrangement when making practical use of the result.
In an ideal quasi-experiment, extraneous influences would be negligible and so would be the
actual after/before change in the control area. In further lighting and crime experiments and
analysis, it is suggested that the measure of effect should be the reciprocal of the odds ratio
used by Farrington and Welsh. Then it would directly describe the effective after/before
change in crime in the treated area. A decrease in crime would give an odds ratio of less
than 1, and an increase in crime, an odds ratio of greater than 1. To avoid possible confusion,
the quantity might usefully be given a different name, say ‘crime ratio’, ‘crime response’,
or ‘crime effect ratio’. It would also seem useful to try to keep direct and indirect effects
separate, or at least night and day effects.
6 FEAR OF CRIME
The literature on fear of crime is extensive (Semmens 1999 [99]), although much of it is not
about lighting. Other bibliographies (eg Nottingham 2001 [75]) provide additional material.
Sherman et al. (1997) [102] has a critical review, including the use of lighting to allay fear.
The widely accepted position is that people tend to fear crime more when they are in dark
or dimly lit places, especially if there are no others or a small number of strangers about. In
given circumstances, fear of crime is almost universally reported as being greater at night
than it is by day, regardless of what the risks of actual crime are. Females are generally
reported as being more fearful of crime than males. Survey data (eg Maguire and Pastore
2002, Table 2.4.1 [64]) tend to support these statements. It therefore reasonable to use
artificial lighting to reduce fear of crime provided that this does not materially increase the
risk of actual crime or cause some other adverse effect such as affecting driver vision or
threatening biodiversity.
Caminada and van Bommel (1980) [16] devised experiments based on the observation
that people tend to feel safer when there is enough ambient light to recognise faces of others
nearby. They found that semi-cylindrical illuminance is a better indicator than other measures,
such as vertical plane illuminance, for defining the face recognition distance. The
cylinder axis remains vertical. The azimuth of the axial plane can be in either of two orientations,
as appropriate: one parallel to the street length and the other normal to it. For
face recognition at 4 m and 10 m, the semi-cylindrical illuminance needs to be 0.8 and 2.7
lux respectively, provided there are no sources of excessive glare present. At 4 m, an alert
person was thought able to take evasive or defensive action if a threat were perceived. The
10 m distance was considered to provide a greater margin for comfort.
Caminada and van Bommel’s work provides an empirical quantitative basis for lighting
as a means to reduce fear. The concept of face recognition distance is mentioned in the
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