Now here’s a scary headline and lead from the NYT:

Life Spans Shrink for Least-Educated Whites in the U.S.

For generations of Americans, it was a given that children would live longer than their parents. But there is now mounting evidence that this enduring trend has reversed itself for the country’s least-educated whites, an increasingly troubled group whose life expectancy has fallen by four years since 1990.

The rest of the story is full of lots more scary language, including references to the “years of life” supposedly being “lost” by folks at the bottom, some not-very-convincing speculation about causes, and a comparison to the shrinkage in Russian longevity after the Soviet system came apart.

The good news is that the bad news isn’t true, or at least that the study in question – done by a heavyweight team and published in Health Affairs – doesn’t show that it is true.

The shoe drops in the sixteenth paragraph:

Researchers said they were baffled by the magnitude of the drop. Some cautioned that the results could be overstated because Americans without a high school diploma — about 12 percent of the population, down from about 22 percent in 1990, according to the Census Bureau — were a shrinking group that was now more likely to be disadvantaged in ways besides education, compared with past generations.

Professor Olshansky agreed that the group was now smaller, but said the magnitude of the drop in life expectancy was still a measure of deterioration. “The good news is that there are fewer people in this group,” he said. “The bad news is that those who are in it are dying more quickly.”

In other words, women in roughly the bottom decile of the educational-attainment distribution in 2008 had a lower life expectancy than women in roughly the bottom quintile of that distribution in 1990. No sh*t, Sherlock. It’s clear from the paper that the authors had the data to do an apples-to-apples comparison, matching the bottom 12% in 2008 with the bottom 12% in 1990, but chose not to.

Now, the finding that whites in the bottom decile have lives about four years shorter than those in the bottom quintile — that is, the group consisting of the very-worst-off tenth and those just above them — is shocking enough. It’s at least suggestive evidence of the human costs of extreme inequality. It might even lead you to say that the policy of making the poor poorer acts as a kind of silent “death panel.” But what it doesn’t suggest is that things are somehow getting worse. (The fact that the U.S. is slipping in the world life expectancy league tables is much more bothersome, but the NYT reports that fact without analyzing it.)

Moreover, it would be hasty to conclude – as the journal paper and the news account both implicitly assume – that the difference came entirely from the social disadvantage created by not graduating from high school, as opposed to the social disadvantage and personal characteristics reflected in not graduating from high school.

Schoolwork is mostly boring, especially if you’re not very good at it, and dropping out means more time, right now, for either paid work or leisure, at some expense in future opportunities. You’d expect, other things equal, that people who “give no thought to the morrow” would be more prone to drop out, and also more prone to do other things that provide current benefit at future cost: smoking cigarettes, for example. You’d also suspect that they had, on average, less attentive parents.

So what we have here is not evidence of a health crisis, or even of growing inequality, but merely an excellent bad example for those who need to teach about sample selection bias.

Fortunately, there’s lots of actual bad news to fret about, so you needn’t miss your MDR of worry.

[Cross-posted at The Reality-based Community]

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Mark Kleiman is a professor of public policy at the New York University Marron Institute.