Saturday, March 28, 2009

Beating The Odds

Above is a link to a BBC article about a man who survived both the Hiroshima and Nagasaki bombings. In 2009, he is still alive at 93.

What are the odds? Well for Tsutomu Yamaguchi, the odds are 100%. That's the way it works for individuals. Either something happens to you or it doesn't.

It is a different matter for populations of individuals. Identify a group of 1000 American men my age. The probability of death by heart disease for a member of that group is pretty high. Let's say 30%. However, each one of those men will or will not die of heart disease. On a more personal level, I will or will not die of heart disease. We may construct the sentence "Kent has a 30% chance of dying of heart disease." That is actually meaningless. Either I will die of heart disease, or I won't.

What is the probability that someone in the same group of 1000 men will be killed by hand gun? Let's say it is .1% So one guy dies via handgun. That tells me that most guys my age would benefit more from taking measures to avoid heart disease than they would benefit from wearing a bullet proof vest. But what if I am the one guy who will be shot. Dang, should have worn the vest! And I could have eaten all the bacon and eggs I wanted.

Here is another way to look at it. If I can convince 1000 men to change their diet and exercise, perhaps the probability of death by heart disease might drop to 20%. Two hundred men die of heart disease, instead of 300. So one hundred lives are saved, right?


Those one hundred men will die of something else. Perhaps the average age at death might go up a few years (that is not a foregone conclusion). However, I cannot conclude that preventative measures mean that I will live longer.

Hearing what the probability is for a population really can't tell me much about what will happen to me. I may have other reasons for eating well and exercising. I might obtain a relatively immediate benefit. But I shouldn't be surprised if I am hit by a truck, struck by lightning, or choke to death on a chunk of steak.

The good new is that I may be the next guy who lives through two nuclear attacks. I may be the guy standing next to the guy killed by lightning. There are a huge number of possiblities open to me, regardless of how many heart attacks hit the middle aged guys around me. I want to live my life thinking about the possibilities for good stuff happening.

I plan to put more energy into the "immediate benefit" stuff.

Photo Credit: Licorne by Pierre J.
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