Thursday, February 10, 2011

The Macdonald Laurier Institute On Canadian Crime

So, it is pretty clear that the Macdonald Laurier Institute (MLS), which put out this study criticizing Stats Canada's reporting of crime statistics, has close connections with the current federal government, whose ideological views the study seems to reinforce. I don't want to make too much of that, because its hard to argue against some of their more generic methodological recommendations: Stats Canada should report more fully and completely and in a more open fashion. So should every body that produces statistical information. But life is tough, and times are hard, and money is short.

So I am only going to touch on a couple of issues mentioned in the study (which, I am proud to say, I have actually read from end to end). Here's the first one:

The annual report on crime statistics, know as Juristat, routinely revises crime statistics from previous years upward in any given year’s report, making annual crime decreases appear more significant than they are.

OK. Below is the relevant time-series from the Juristat report in question. It displays the ebbs and flows in Canada's Crime Severity Index (note: a chart showing the more traditional measure of crime by volume can be found here. There is no accompanying graph, but it would look generally similar to the one below):
What the analysts from MLI are saying is that, when Stats Can reports the data point for 2009, it will be measured against a point on the graph representing 2008 that has been upwardly revised. Thus any decline year-over-year will be accented, and any increase muted. That's not surprising: an initial StatsCan crime report is issued, more data comes in that was not available at the publication date, and the report and accompanying graph is updated. It isn't as though there is anything that could be done to get around this this, other than making publication date so late that revisions are unnecessary.

But, more importantly, the issue MLI identifies only really applies to the last couple of data points on the X-axis of the graph above. Stats Canada figures might be revised once or twice, but eventually they become pretty much set in stone, so the revisions MLI notes will not alter the overall shape of the graph. Which is to say, the revisions will not show a long-term downward trend if there is an upward trend in the underlying crime data. The downward trend in crime that Stats Canada notes really is there.

There's one other point in the MLI study that I would like to touch on, because it seems representative of a number of the criticisms that they make:

This is, as the MLI admits, a methodological complaint. Stats Canada chops up and recombines its numbers based on a series of methodological decisions. But these are not the only decisions that could have been made, and indeed when you make re-cut the numbers as per MLI, you get table 7 above. The question then becomes whether this, as MLI asserts, is a "much better" way of chopping up and recombining the numbers or not, and whether the result is worthy of highlighting in the Stats Canada report, or not.

I will not defend the agencies various methodological decisions in this space, for they have already done on their own behalf, here.


pogge said...

Your last link gets me a Page Not Found error at the Montreal Gazette.

bigcitylib said...

Thx. Should work now.

Gayle said...

Scott Newark used to be a crown prosecutor in Alberta. He has an ideological bent that cannot be discounted when he publishes something like this. StatsCan, on the other hand, is objective.

As for the issue of including attempted murder in the homicide statistics - this is a stupid argument. StatsCan keeps statistics of reported and charged crime, not convicted crime. If we start including attempted murder that simply allows the police to artificially increase the statistic (thereby giving them ammunition to argue for more funding) because they can simply charge someone with attempted murder instead of aggravated assault and then claim homicides are going up.

Any criminal lawyer will tell you that attempted murder is extremely difficult to prove. Any criminal lawyer will also tell you that the police are often guilty of over charging. I once worked with a kid who was charged with 15 counts of attempted theft of motor vehicles, all of which were reduced to a single ticket once the lawyers looked at the case. A couple years ago in Edmonton 4 boys were charged with murdering a guy on a bus. The headlines were screaming for their heads. Yet, once all the facts were out it was apparent those 4 boys were defending one of their friends from an unlawful assault by the deceased (he was choking him). They pushed the guy who fell and hit his head. It was a fluke accident and all charges were dropped. Those 4 homicide charges still go down in StatsCan as 4 homicide charges, notwithstanding the fact they were not substantiated by any facts.

Mark Francis said...

It's a hack piece.

I read it too. There is an inherent dishonesty in the 'study' -- it presents many issues as unexplained (he loves the word 'inexplicable') by Stats Can, when in fact they are explained elsewhere. It's intellectual dishonesty, or at least incompetence, to not consider all reasonably available materials.

This guy would look out his window at night, and conclude there was no sun.

The publication he is criticizing is not supposed to be the be all and end all of crime stats. It's just an addendum. One could be excused for thinking that this is all he's ever read on the topic.

And though he is critical of crime stats these days, he seems uncritical of violent crime stats he compares against from the 1960s, which we know are severely under-representative of violence in society at that time. He even throws in a gratuitous "Shouldn't we be investigating why the 60s were better?". I mean really. Sexual assaults, still under-reported and not taken seriously enough, were barely acknowledged back then, as were domestic assaults.

Political fluff, written to get Flaherty et al pimping the private sector for more funding for the institute.

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