Friday, August 04, 2006

Poor use of percentages

One of today's top "news" stories in Britain has been that Britons, especially in the north of England, are drinking themselves to death. This we knew already, but now the Centre for Public Health has made local profiles in an effort to bring the issue closer to people. Also, to illustrate the seriousness of this, professor Mark Bellis, the director of CPH was saying that everyone in Blackpool and other northern regions is currently throwing away 23 months of their lives as a result of their heavy drinking habits.

And this was the mistake. When some happily drunk party-goers were interviewed for tv news, none of them thought this was serious. As one of them said, if you are going to live to be 77 or 78, what's 76 compared to that? Indeed. When you are 20, you don't exactly look forward to those last years of your life, and the difference between dying at 76 and 78 is small, or the first would actually be favoured, as it would mean that you need to spend a shorter time being a boring old-timer.

Unfortunately, this is not how it works. They were simply saying that the life expectancy in the Northern regions is 23 months lower than the national average is, and that the biggest contributing cause they can see is drinking. I think. There might be some more sophisticated stats involved, they might be able to factor out the alcohol-related deaths and the 1 to 2 years was arrived to by looking at the impact of these to the average life expectancy. I can't be bothered to check, beacuse it's irrelevant to my point. Which is that 23 months on the level of averages means that it covers all tea-totallers and church-ladies who take one sip of sherry after Sunday service. And the difference to the average is contributed by those who binge every week, meaning that they are actually likely to die at 50 when their livers implode, and not at all likely to make it to 76. Many of them actually die accidentally much earlier, and their drinking habits contribute to this either directly or indirectly.

While scare-tactics (and showing swollen livers, clogged arteries and mangled bodies in tv-ads etc.) tend to turn against themselves as well, I think that the message of this study will be thoroughly misunderstood. While the CPH was trying to say that binge drinking is very dangerous and its effects can be measured, and what is discovered is unsettling, the message the bingers take home is that what they do is relatively safe, and party on.

I'm beginning to think that differentiation on your heath (insurance) costs based on your drinking, smoking and eating habits is the only way to make a difference. While this would be nearly impossible to implement, not to mention very unpopular as a policy, perhaps threatening with it works better than threatening with liver failure and heart disease.


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