"We can't allow things that are inaccurate to stand." — The Word of Our Dan, February 19, 2008.

Sunday, October 17, 2010

Oh noes! Crimes!

A strange and contra-factual statistical claim in a James McLeod piece in Saturday’s Telegram:

Homicide rate on the rise

The province’s chief medical examiner said the number of homicides here is on the rise.

There were 70 homicides in the province between 1997 and 2009.

Stop. Right. There.

The phrase “70 homicides in the province between 1997 and 2009”, comprises thirteen calendar years if counted inclusively, which means an average of about 5.4 homicides per year. (“Homicide”, in the criminal law sense of the term, includes first- and second-degree murder, manslaughter, and infanticide.)

And that is about all the phrase “70 homicides in the province between 1997 and 2009” can tell you. It says absolutely nothing about whether the number or rate of homicides are increasing, decreasing, or stable.

So, what is actually going on?

Well, with a note of caution since the local year-over-year numbers are almost too small to play with in the first place, the answer would seem to lie somewhere between “stable” and “decreasing”. This chart* compares the homicide rate per 100,000 population for Canada, the province, and the St. John’s metropolitan area, since 1961 at the national and provincial level, 1981 for metro St. John’s:

A few things worth noting:

First, despite the widespread popular belief to the contrary, the homicide rate in Canada has been on a relatively steady downward trend since the peak of around 3 per 100,000 was reached in the mid-1970s.

Second, with the exception of a few outlying years, the homicide rate in the province and in the St. John’s metro area is consistently at, or much below, the all-Canada figures.

Third, while there are some years in which the homicide rate in the province or in St. John’s spike upwards, there is no pattern to the spikes. “Spike” years are followed, thankfully, by “crash” years, such as 1999 and 2004 when there were just two homicides reported in the province, 2001 (just one), or 1990 (none).

In case you are having (understandable) trouble spotting any local trends in such blippy figures, here is the same data, averaged out over ten years so as to make long-term trends visible. For example, the figures for 2008 are the trailing averages for the ten calendar years from 1999 to 2008 inclusive:

While there was a long-term increase in the homicide rate in St. John’s through the 1990s, that trend reversed itself a decade ago, to the point where the long-term figure for St. John’s recently dipped below the provincial rate.

And the provincial rate is stable.

There is absolutely no support to be found in the official crime statistics for the assertion that homicide is on the rise in Canada, in Newfoundland and Labrador, or in St. John’s.

It’s a good thing though, that innumeracy isn’t a Criminal Code offence.

[Data source for charts: Statistics Canada CANSIM Tables 253-001 and 253-004.]

Labels: , ,


At 1:17 PM, October 17, 2010 , Blogger Edward Hollett said...

Part of the problem with the story is that Avis compared an eight year period with a 12 or 13 year period and then went "A-ha!".

Macleod just ran with what he had. The problem is with Simon's characterisation.

However, as you noted, part of the period he selected includes that uptick period in St. John's and didn't really look at the patterns or actual trends.

Even if you look at absolute numbers - as opposed to number of homicides per 100K population, there is still not something to get alarmed about.

And the claim about two serial killers? Without much more evidence and a discussion of the specific cases, Avis appears to be was irresponsibly sensationalising.


Post a Comment

Subscribe to Post Comments [Atom]

<< Home