Media and Crime Statistics: A lack of critical analysis

January 4, 2014

Both the Ottawa Citizen and Ottawa Sun reported that in 2013 Ottawa saw a 28 per cent decrease in the number of Christmas time  break and enters.

The Ottawa Police’s PR department were quick to point out that that the decrease is due to increased incarceration of offenders – more bad guys behind bars.

A 28 percent reduction in break-ins sounds impressive.  However, looks can be deceiving and unfortunately the Sun and Citizen applied little intellectual rigour to their reporting of the statistics or to the police’s explanation for the decrease.

The main issue with attributing any meaning to the 28% decrease in break and enters is the limited nature of the sample size.

There were 23 break and enters over the Christmas period this year compared to 32 last year.  The limited nature of these sample makes it very difficult to separate meaning from noise.

In short, due to the small sample size the influence of randomness can prevent meaningful analysis.

I won’t launch into a long post about sample size problems – it is however a fascinating topic that cries out for its own lengthy post (as a starting point this short baseball video may help explain some of the problems with small sample sizes).

We are talking about 9 fewer burglaries.  Are the 9 fewer break and enters due to incarceration of offenders or is the decrease due to random chance or can the decrease be explained by some other combination of factors (weather, citizen vigilance, a larger trend, the decrease in household valuables, etc..)?

The police provide no information to support their contention that incarceration of burglars is making our homes safer and the media asks no questions on this issue.

How many burglars are incarcerated, when were they incarcerated, how many burglaries were they responsible for, did they commit a break and enter last year?  Without this type of information there is simply no way to test the police’s theory.

It is a good thing that there are fewer residential burglaries over the holidays.

It may even be natural for the police to want to take their share of the credit for the decrease.

However, it is most unfortunate that the Ottawa media is satisfied with simply parroting the Ottawa Police’s simplistic analysis of crime statistics without applying any critical evaluation.

Crime, crime trends, and criminal justice are complicated issues.  The public deserves criminal justice analysis from the media that is fair, balance, and critical.  In short – reporting that rises to more than reprinting police quotes.