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Kostic, A., & Djokic, L. (2014). Subjective impressions under LED and metal halide lighting. Lighting Research and Technology, 46(3), 293–307.
Abstract: In order to compare subjective impressions created by LED and metal halide ambient lighting, a pilot project was conducted in a Belgrade park. All general requirements for an adequate comparison of subjective impressions were fulfilled. The survey was conducted using a questionnaire related to all aspects the researchers considered relevant for subjective evaluation of illuminated pedestrian paths in parks. It was concluded that the respondents, both those who had and those who did not have previous knowledge in the field of lighting, strongly preferred the use of metal halide lamps for the illumination of parks, which is in opposition to the statements of some LED manufacturers. It was also shown that light level and feelings of safety and comfort are evaluated as most important.
Lin, Y., Liu, Y., Sun, Y., Zhu, X., Lai, J., & Heynderickx, I. (2014). Model predicting discomfort glare caused by LED road lights. Opt. Express, 22(15), 18056.
Abstract: To model discomfort glare from LED road lighting, the effect of four key variables on perceived glare was explored. These variables were: the average glare source luminance (Lg), the background luminance (Lb), the solid angle of the glare source from the perspective of the viewer; and the angle between the glare source and the line of sight. Based on these four variables 72 different light conditions were simulated in a scaled experimental set-up. Participants were requested to judge the perceived discomfort glare of these light conditions using the deBoer rating scale. All four variables and some of their interactions had indeed a significant effect on the deBoer rating. Based on these findings, we developed a model, and tested its general applicability in various verification experiments, including laboratory conditions as well as real road conditions. This verification proved the validity of the model with a correlation between measured and predicted values as high as 0.87 and a residual deviation of about 1 unit on the deBoer rating scale. These results filled the gap in estimating discomfort glare of LED road lighting and clarified similarities of and differences in discomfort glare between LED and traditional light sources.
Marchant, P. R. (2011). Have new street lighting schemes reduced crime in London? Radical Statistics, (104), 39–48.
Abstract: Crime counts published by the Home Office for the Metropolitan Police
Crime and Disorder Reduction Partnership areas have been collated
across the years 2003-2009. The crime counts over time have been
modelled taking into account the âmultilevelâ (years within areas)
nature of the data. The key variable of interest, as a predictor of
within-area change of crime, is the proportion of a Core Investment
Period of new Private Finance Initiative street lighting which had been
completed up to the given time point as a predictor of within area
change of crime. The final model gave a 95% confidence interval for
the multiplier by which the number of crimes is increased of (0.87,
1.11), for a fully implemented lighting programme, consistent with
Marchant, P. R. (2010). What is the contribution of street lighting to keeping us safe? An investigation into a policy. Radical Statistics, (102), 32–42.
Abstract: Lighting of roads is said to be of benefit beyond giving the ability to be
able to see in the dark. It is claimed for example that lighting reduces
crime and traffic accidents by a considerable amount and it is
therefore necessary to have it for these reasons. My view remains that
this claim lacks evidence of a sufficiently high standard to warrant
using public safety as an argument. On the other hand there are
reasons why having a lot of light at night might be a bad thing. This
work continues a previous talk and article for Radical Statistics
My initial interest in this area was sparked through my interest in
astronomy because light pollution makes it hard to appreciate the
wonders of the night sky. It seemed to me that the belief that lighting
reduces crime was questionableâ¦. I then embarked on investigating
the crime reduction claim and found it suspect, as detailed in the
2006 Radical Statistics article. (See also Marchant 2004, 2005, 2007,
Marchant, P. R. (2006). Investigating whether a crime reduction measure works. Radical Statistics, 91.
Abstract: Crime is a serious business. It causes great distress and fear. It costs a lot
to deal with its consequences. In these regards crime shares much with
the problem of ill-health and disease. The application of sound science and
statistics has allowed great strides to be made in dealing with problems of
ill health. Medical statistics is one of the recognised, established
disciplines involved in researching healthcare.
The parallels between research in crime reduction and in healthcare do
appear to differ in terms of quality. Although there is still room for
considerable improvement in researching health-care, an investigation
into the underpinning of statistical methods used indicates that the
problems are substantially worse in the study of crime. The consideration
given to statistics in crime studies seems rather flimsy, yet important
claims are made which are statistical at source and may affect policy, and
so can have considerable costs attached. Therefore, for example, it is
important to know whether the underlying crime level has really changed,
rather than just being the result of perhaps sampling variation or some
artefact giving rise to statistical bias or systematic error. This is necessary
when trying to determine whether a Crime Reduction Intervention (CRI)
has actually worked.
I started examining the scientific basis of the claim for the effectiveness for
one particular CRI, basically because I was concerned about negative side
effects and I thought the claim implausible. I remain concerned and
unconvinced. The statistical issues and concerns I raise apply also to
investigating other CRIs and to existing published analyses.
This piece extends work presented in Marchant (2006); earlier work on the
statistical issues involved can be found in Marchant (2005a, b; 2004).