Tuesday, October 30, 2007

The Causal Relationship Will Be Between This Stick And Your Head

As a recovering scientist, one of my public policy bugbears is the flagrant misuse of statistics. What is worse is when that misuse comes from the academics themselves...

The Independent on Sunday reports the findings of a study in the journal Environmental Research claiming that the fall in violent crime in the US in the 1990's was the result of banning leaded petrol. Researchers report a "very strong association" over a period of fifty years between childhood exposure to lead and crime rates in adulthood. Similar trends are reported to have been seen in individual US cities and in other nations around the world.

This is by no means the first study to suggest a left-field cause for this particular drop in the crime rate, as at least one blog this week (though which one I've shamefully forgotten) pointed out when referring to The Impact Of Legalized Abortion On Crime, co-authored by Freakonomics' Steven Levitt.

Now let's face it, you don't have to be a recovering scientist to realise that the flaw in these studies is the failure to recognise that even the strongest correlation is not necessarily causal (although if you do need help with this concept, Wikipedia offers some delightful examples...)

What all this brings home to me, however, is the scale of the task we face as liberals on crime and the importance of making an impact. Pretty much everything Labour and the Conservatives (and, for that matter, the SNP and Plaid) say and do on crime is predicated on the idea that crime is perpetrated by bad people and that if there were only less bad people things would be all right.

That there are serious social scientists eager to support that assumption is of real concern. That there are serious politicians who would use those assumptions to ignore the deprivation that is the real cause of crime is just shameful.

1 comment:

James said...

I'll go along with that, so long as you aren't suggesting that there isn't a link between the number of pirates on the High Seas and global warming. Because that would be heresy.