Shining a light on evidence-based policy: street lighting and crime

Many social, scientific and political debates are conducted using numerical information to support an argument. The question is: “does the evidence stand up?” Certainly the question ‘does a crime reduction method work?” is one which must ultimately be settled using numbers, because if the method does work, crimes will be fewer, on average. This brings in the discipline of statistics, simply because we need to be convinced that any reduction observed is more than might reasonably be expected to have occurred anyway; i.e. due to the many other factors which can affect the number of crimes committed and counted.