Arnold Kling  

More on the Height of Bravery

North on Adaptation... Watch the Platforms, Not the W...

A commenter on my post on the slowdown in America's height gains refers to Michael R. Eades, who points out that the original research was pretty much self-refuting.

It should be real easy to determine whether the above sociological jibberish holds any merit: simply compare wealthy Americans (all of whom presumably have decent healthcare) to wealthy Europeans and poor Americans (who presumably have bad healthcare) to poor Europeans (who supposedly have the same health care as the wealthy). If the wealthy Americans and Europeans are the same height and the poor Americans are shorter than the poor Europeans, then we could maybe make a case for a difference in health care. If both rich and poor Europeans are taller than their American counterparts, then it’s tough to make a case for a healthcare difference causing the problem.

The authors do look at this. And what do they find?

The lagging U.S. height performance is not caused by a long left tail in the height distribution. Heights are normally distributed and the whole U.S. height distribution is shifted to the left. In other words, rich Americans are shorter than rich western Europeans and poor white Americans are shorter than poor western Europeans.
Case closed. Or as Samuel Johnson would have said, “There’s an end on’t.” It ain’t a difference in the healthcare system.
Eades goes on to propose increased consumption of soft drinks, either by itself or as a displacement for milk, as the culprit. That is plausible, but unproven speculation.

My point in bringing this up is that the original study commits a classic fallacy, which is to label the unexplained in a regression. When you use regression analysis, you include some variables and you exclude others. The latter are excluded because you cannot measure them or you do not know what they are. They are called the "omitted variables" or "error term" in regression terminology.

It is a fallacy to interpret the error term as representing exactly one omitted variable--health care in this case. Another classic example of this fallacy was committed by Christopher Jencks, who found that his measures of IQ and schooling together explained less than 50 percent of the variation in earnings, and decided that the remainder had to be "luck." Again, he was labeling his ignorance, not making a valid inference.

What I find disturbing is that Paul Krugman devoted a column to trumpeting this research. I cannot imagine in a million years that he would have been as laudatory of an equally shoddy paper that reached a conclusion in support of American capitalism.

I, too, am guilty of wanting to give the benefit of the doubt to papers that support my viewpoint. But I would like to think that I approach all research with at least some methodological skepticism, rather than assume that if the results come out to my taste it must be good work. In any event, when I link to a paper, I strongly urge you to read it yourself and to think about possible flaws.

Comments and Sharing

CATEGORIES: Economic Methods

COMMENTS (6 to date)
dearieme writes:

Oh, the idea that the explanation could be "healthcare" in the sense of doctors-and-nurses is so obviously silly that no-one would take it as anything but kite-flying, would they?

Floccina writes:

Speaking of bias this is a link that I saw on the Brad Delong Blog:

June 16, 2007

“Tax Gap Puts Private Equity Firms on Hot Seat

This week, Goldman Sachs, Wall Street’s most profitable firm, reported that it earned about $3.4 billion for the second quarter. As always, it set aside a big chunk of money — $1.1 billion, or about 32 percent — to pay corporate income taxes on its healthy profits.

Then there’s the Blackstone Group — the first big-name private equity firm to proceed with plans to go public in the United States — whose business is similar in many ways to Goldman’s. In the first quarter, Blackstone, a privately run partnership dominated by Stephen A. Schwarzman, earned about $1.1 billion before taxes. Its tax bill? Just $14 million, or 1.3 percent.

Even after the Blackstone partners pay their share, the total should still come to less than half that of their Wall Street counterparts.

The gap is the latest example of an advantage that has existed for decades but gone largely unnoticed — until now. It has allowed private equity firms, like Blackstone, to operate as partnerships and to pay far lower tax rates than corporations, giving them an advantage that critics say is unfair.

Moreover, their partners generally pay no more than 15 percent in taxes on most of the money they earn from the firm, compared with the top individual rate of 35 percent....”

As far I can figure out and according to my accountant the 15 percent dividend tax rate is not applicable to partnerships, s corp’s, or LLC’s. In partnerships, s corp’s, or LLC’s the owners pay taxes on earning/profits and make distribution (not really dividends).

Unless I am wrong and the above partnership is a special case (which I always hold out as a possibility because tax code is so convoluted – but it would have to be a special case) the above article is scandalous. The journalist should have known better.

What does this article say about the New York Times.

jaim klein writes:

Omitted variable

But of course. They measured only vertical length. But Americans started to grow less vertically and more horizontally. Include the horizontal variable and you will have Americans that are bigger than Europeans. More money spent on health and on food produces more voluminous Americans.

Bryan Pick writes:

Ah yes, the "residual fallacy." I recently wrote a post that was partly about how the fallacy is used to "prove" sex discrimination in wages... just like it's been used to "prove" genetic inferiority.

Jason Malloy writes:

An article in the New Yorker several years ago 'explained' this by asserting that the American poor were making the American rich shorter as well by getting their poor germs on them:

As more and more Americans turn to a fast-food diet, its effects may be creeping up the social ladder, so that even the wealthy are growing wider rather than taller. “I’ve seen a similar thing in Guatemala,” Bogin says. “The rich kids are taken care of by poor maids, so they catch the same diseases. When they go out on the street, they eat the same street food. They may get antibiotics, but they’re still going to get exposed.”... If the poor are pulling all of us down with them, some economists say, why didn’t Americans shoot up after the war on poverty, in the nineteen-sixties? Komlos isn’t sure. But recently he has scoured his data for people who’ve bucked the national trend. He has subdivided the country’s heights by race, sex, income, and education. He has looked at whites alone, at blacks alone, at people with advanced degrees and those in the highest income bracket. Somewhere in the United States, he thinks, there must be a group that’s both so privileged and so socially insulated that it’s growing taller. He has yet to find one.

The article also asserts that "By and large, though, any population can grow as tall as any other". Mmm hmm. Bad assumptions lead to bad conclusions.

Brad Hutchings writes:

Krugman is smart enough to know that this result cannot pass the sniff test for anyone with a critical mind. So, being the smart people we are, we react to the result by deconstructing it and finding fault. Amongst ourselves, we know it's BS and we know why. Meanwhile, amongst Krugman's readers, many of whom are very happy to hear such a result, it pretty much goes unchallenged. In that market of ideas, Krugman wins.

Sometimes you fight BS with S from a bigger B. This height thing reminded me of my last trip to Paris, in September 2000. On a free day (it was a biz trip), I walked clear from La Defense on the west side of Paris to Notre Dame (on the east) and back. 16 miles or so round trip. As I got past Notre Dame, my Nike sandals broke. So I stopped in a little shoe shop. I wear size 11 (a slightly above average size in my recent experience in the sneaker game) in most shoes, so I told the shop owner. She converted to the European size and told me she didn't know if she had anything that large in stock because French men's feet aren't so big. My quip then was "that's not all that's small on French men" but my thought now is "obviously a result of socialized medicine". Any academic care to study the issue?

Comments for this entry have been closed
Return to top