Wednesday, November 10, 2010

Prerequisite for going to the doctor: Math

It's become apparent to me that the innumerate masses in America must be having a hard time making good health care decisions. The information your doctors have is too complex for them to just sum it up for you - they'd basically be making the decisions for you. They can't do that, you have to interpret the data yourself. Innumerate people can't do anything with the data they're given, so they just make a judgment based on how it sounds.

Some data sound very worrisome when they are not. "This test result means your risk for Disease X is doubled". That sounds as if you're likely to have the disease. But it doesn't mean much unless you know what the baseline risk is. If it's 1 in 5000, then it's probably not worth worrying about the new test result. Odds are 99.96% that nothing is wrong with you. If you aren't able to figure this out, you might insist on a painful or invasive procedure to rule out the disease, just to alleviate your worry.

"Your child's weight is 20th percentile". That might sound dangerously small, but all it means is she's smaller than 80% of her peers. It doesn't tell you how much smaller. If you look at the distribution of children's weights, you might find that the difference between 20th percentile and 50th (average) is just a few ounces.

I could go on with dozens of examples. Why aren't there word problems in math books like this, rather than made-up scenarios about apples and train schedules? Maybe kids wouldn't be so quick to dismiss math as "something they don't need in real life".


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