Saturday, January 10, 2009

Beer and ... crime

I often glimpse the local newspapers while visiting a foreign country (as long as it is in a language I can read). Yesterday, the Australian Herald Sun had the article "Drop in light beer sales blamed for surge in street violence".

The facts presented: "Light beer sales have fallen 15% in seven years, while street crime has soared 43%". More specifically: "Police statistics show street assaults rose from 6400 in 2000-01 to more than 9000 in 2007-08. At the same time, Victorians' thirst for light beer dried up."

The interpretation by health officials: "there was a definite connection between the move away from light beer and the rise in drunken violence."

The action: There is now a suggestion to drastically reduce tax on light beer to encourage people to switch back from full-strength beer.

I am far from being an expert on drinking problems or crime in Australia (although they are both very visible here in Melbourne), but let's look at the title of this article and the data-interpretation-action sequence more carefully. The title Drop in light beer sales blamed for surge in street violence implies that the drop in light beer sales is the cause of increase in violence. Obviously such a direct causal relationship cannot be true unless perhaps retailers of light beer have become frustrated and violent... So, the first causal argument (I suppose) is that the decline in drinking light beer reflects a move to full-strength alcohol, which in turn leads to more violence. If there indeed is a shift of this sort, then the decline in light beer sales is merely a proxy for violent behavior trends*.

The second causal hypothesis, implied by the proposed action, is that beer drinkers in Victoria will switch from full-strength to light beer if the latter is sufficiently cheap.

To establish such causal arguments I'd like to see a bit more research (which might already exist and not mentioned in the article):
  • Have people in Victoria indeed shifted from drinking light beer to full-strength beer? (perhaps via a survey or from transactional data at "bottle" stores) -- there might just be an overall decline in beer consumption, as well as an overall increase in violent behavior like in other places in the world
  • Has violence increased also by non beer drinkers? What about drugs, violent movies, shift of populations, economic trends, global violence levels?
  • If such a shift exists, what are its reasons? (e.g., better quality of full strength beer, social trends, price)
  • What segment of beer drinkers in Victoria becomes violent? (age, gender, employment, income, where they buy beer, etc.)
  • Is today's beer drinking population different from the population 7 years ago in some other important ways that relate to violence?
  • Has violence been treated differently over the years? (police presence, social norms, etc.)
  • Determine how price-sensitive today's drinkers-become-aggressors are.
Only after answering the above questions, and perhaps others, would I be comfortable with seeing a causal relationship between the price of light beer (compared to full-strength beer) and the levels of aggression.

And if beer drinking is indeed a cause of violence in Victoria, how about adopting behavioral and educational ideas from other countries like France? Or maybe alcohol is simply loosening the inhibitions on the growing aggressive 21st century society.

*Note: Even if light beer sales are merely a proxy for crime levels, they can be used for predictive purposes. For example, police stations can use light beer sale levels for staffing decision.

1 comment:

Unknown said...

This same type of implied causality is used all the time by politicians & pundits to spin a topic and persuade the public to take their viewpoint. Fox News takes this to new heights by blaming anything and everything on some liberal agenda. Such as the economic recession being caused by a rise in same-sex marriages, or increased gas prices the result of illegal immigration. How can they not care where their facts and numbers come from to back their rants?