Wednesday, January 03, 2007

Education And Health

An interesting New York Times article discusses some of the research that has gone into disentangling the relationships between higher levels of education and longevity. It's been known for some time that education and health in general are positively correlated ( when one goes up, so does the other, on average), but understanding why this correlation exists is harder.

For example, it could be that ill health in childhood causes people to have less education. Or that higher education levels are just a proxy for higher income levels and that it is more income which makes people healthier. Or it could be that education in itself somehow protects health, perhaps because schools teach either health information directly or skills which can also be used to get better health information. Or it could be that the jobs educated people have cause less wear-and-tear than the jobs that are available to those without education. Or education might change the way people are able to make choices which involve short-term discomfort or sacrifices but long-term health benefits.

This last-mentioned hypothesis is one which Adriana Lleras-Muney, one of the researchers cited in the NYT piece, seems to support:

Dr. Lleras-Muney and others point to one plausible explanation — as a group, less educated people are less able to plan for the future and to delay gratification. If true, that may, for example, explain the differences in smoking rates between more educated people and less educated ones.

Smokers are at least twice as likely to die at any age as people who never smoked, says Samuel Preston, a demographer at the University of Pennsylvania. And not only are poorly educated people more likely to smoke but, he says, "everybody knows that smoking can be deadly," and that includes the poorly educated.

But education, Dr. Smith at RAND finds, may somehow teach people to delay gratification. For example, he reported that in one large federal study of middle-aged people, those with less education were less able to think ahead.

"Most of adherence is unpleasant," Dr. Smith says. "You have to be willing to do something that is not pleasant now and you have to stay with it and think about the future."

He deplores the dictums to live in the moment or to live for today. That advice, Dr. Smith says, is "the worst thing for your health."

Hmm. Could be. On the other hand, the research itself can't single out this explanation as the most likely one. Economists call the above phenomenon "time preference", the preference for present consumption over future consumption. We all have some time preference. Just think of whether you'd rather have a thousand dollars today or in ten years' time. The preference is caused by the future being uncertain, the possibility that you will not be around in ten years' time and the fact that waiting for ten years requires abstinence. What the explanations in the NYT article add to this is the idea that the less educated might have a higher rate of time preference.

Is this true? And if it is true, how does education affect time preference? I can see the point of lower incomes causing a higher rate of preference for the present, because survival is more important than whatever might happen in some far future date. In a way, if the present is a miserable place to be, anything that can assuage the misery rises in value.

I'm wondering if the connection between education and health via this avenue isn't still contaminated by the lower wealth levels of those who are less educated. Even if we manage to control for income and current wealth in studies of health, we may not be controlling for the person's lifetime wealth. Education could then be the proxy for that as well as any other effects it might have on health.