Monday, March 15, 2010

A defence of the Spirit Level that is not really a defence

Sociology-professor Denny Vårgerö today writes (in Swedish) an article about inequality and mortality. He has a graph that links income with mortality, showing that lower income people are more likely to die.

1. First a small point: Vårgerö writes that our critique of the Spirit Level is that the choice of countries and the measure of inequality influences the results.

Our critique is much more powerful than that. In ALL definitions of inequality and REGARDLESS if we looked at 21, 23 or 28 countries, there was no statistically significant relationship at conventional levels between inequality and mortality.

The writes or the Spirit Level are deliberately confusing their readers in PRETENDING that we are just nitpicking about inequality measures.
Professor Vårgerö: Don't take their word for it, they are fooling you.

2. A larger point:

This graph does not in itself prove that lower inequality would save lives, because of reverse causality. If you are of poor health, you will earn less, and also be more likely to die. This is extremely important for interpreting his graph.

Vårgerö neglects this problem, which I find astonishing. The left and left leaning social scientists in Sweden really needs to learn about causality.

Furthermore, there are missing variables that co-determine life expectancy and income. A particularly important one is education: more educated people take care of themselves better, and earn more. Vårgerö mentions this second point at least.

3. The most important point:

The claim in the Spirit Level is not that low income kills you as Vårgerö seems to think. It is that the high income for the rich *cause* others people in society to die from stress. That is why they do all those cross country comparisons, they believe the income of OTHER PEOPLE is what is the core of the issue, not your own income (as Vårgerö uses).

It is of course far from common sense observations that educated people take better care of themselves and thus live longer. (and people with more self-discipline are more likely to get educated in the first place).

It is also different than Vårgerös point that lower income causes you to die.

If the Spirit Level was just claiming that low income is bad, it would not have gotten so much attention. Everyone already know that (although the causal effect on mortality in countries with Universal Health care have not been understood).

Vårgerö does not seem to realize that they make a much stronger claim: that the income of other people determined my health, and that high income is bad. That is why they are obsessed with inequality measures, rather than income measures.

Does Vårgerö really want to defend the astonishing claim in the Spirit Level? If so, does he have any casual evidence for it? He only has my own income and my chance of dying in the graph, which leads me to believe he has not studied the argument in the Spirit Level carefully.

I already posted this paper by Magnus Johannesson and Ulf-G. Gerdtham about Sweden, but let me post it again:

"We test whether mortality is related to individual income, mean community income, and community income inequality, controlling for initial health status and personal characteristics. The analysis is based on a random sample from the adult Swedish population of more than 40,000 individuals who were followed up for 10–17 years. We find that mortality decreases significantly as individual income increases. For mean community income and community income inequality we cannot, however, reject the null hypothesis of no effect on mortality."

Lower income is associated with mortality (the causality problem is of course still there), but income INEQUALITY is not. According to Johannesson and Gerdtham Vårgerö is right and the Spirit Level is wrong. But Vårgerö does not understand in his SVD article that he and the Spirit Level are making different, in some terms opposite claims.

He is defending people who actually disagree with him. I suppose one reason is that The Spirit Level argument about inequality killing you through stress is hard to defend scientifically.

A simpler reasons seems to be that Vårgerö thinks The Spirit Level just sais inequality=bad, and we are saying inequality=good, so he wants to defend them.

But I don't think inequality is good, and I strongly believe in raising the income of the poor in Sweden, and even stronger in raising their health status. What I oppose to is the bad science in the Spirit Level, and the claim that lowering the level of the educated will magically help the uneducated health status.

4. Look for a moment at this graph from the Swedish National Institute of Public Health. It shows unhealthy habits and education and income. The lower your education and the lower your income, the more likely you are to have unhealthy habits.


5% of Swedish men with high education smoke, compared with 27% of the unemployed and 32% of those on long sick-leaves.

The first question is, why do we think these people are more likely to die? Because they have low income, or because they have bad health habits?

The second question is: do we think they have bad habits because the rich have high incomes? If the poor stayed poor and uneducated, but I raised the marginal tax on the rich, would mortality of the poor go down?

The answer matters enormously for policy. If you believe the junk science of the Spirit Level, the problem in society are the rich and educated. If we target them, and make them poorer, social problems of the poor will automatically solve, because they were caused by envy and relative status.

The Swedish health policy instead sensibly focuses on the behavior and living standard of the poor, and tried to solve them through education, information, taxes on alcohol and tobacco. If the Spirit Level is correct, we have been silly to do this. The problem are not the poor, the problem is the rich! If you see a kid in school smoking, don't focus on him. Find the kid from a good home not smoking and getting straight A:s, and punish him. This will reduce the stress of the kid smoking, and solve his health problems.

Does this sound insane to you? It should. And if you want to make insane claims like this, at least have some empirical evidence, which demonstrates causation.

No comments:

Post a Comment