A little exercise in reasoning and in politicized science reporting

The Washington Post had an article with this headline that caught my eye:
"Study Finds Eating Red Meat Contributes to Risk of Early Death."

Does the study really "find" that? Let's see what the article actually says...

The lead paragraph: "Eating red meat increases the chances of dying prematurely, according to a large federal study that offers powerful new evidence that a diet that regularly includes steaks, burgers and pork chops is hazardous to your health."

Oh my! Let us read on to see how this study demonstrates this. The next graph says:

"The study of more than 500,000 middle-age and elderly Americans found that those who consumed the equivalent of about a small hamburger every day were more than 30 percent more likely to die during the 10 years they were followed, mostly from heart disease and cancer. Sausage, cold cuts and other processed meats also increased the risk."

Hmmm...can you see the logical fallacy revealed here?

The second paragraph tells us the study discovered an association. People who eat certain meats are more likely to die. But is that the same thing as causation?

The answer, dear reader, is that it is not. Why not?

Well, for example--aren't you curious, as I am, to know anything else about these folks who died earlier? And about those who, despite stuffing all that meat down their gluttonous throats, did not proceed to die earlier? Why weren't they 100% more likely to die earlier?

Perhaps because of...other variables? Such as exercise, weight, smoking, stress, other vices...who knows what?

The article says, later, that the study accounted for those variables. Over a half-million volunteers filled out detailed questionnaires in 1995; then, "Over the next 10 years, 47,976 men and 23,276 women died."

Okay; that's concerning, no question. But again, this inquiring mind wants to know: how inquisitive were the researchers into other behaviors and stresses, and changes in habits, over the following ten years?

The article proceeds to say that "routine consumption of fish, chicken, turkey and other poultry decreased the risk of death by a small amount, the study found."

It occurs to me that they may have cause-and-effect backwards: perhaps people who lead healthier lifestyles tend to eat fish and turkey; and those attached to decadence prefer those "bad meats" we just heard about.

In the interest of full disclosure, I happen to love all those "bad meats" and I don't keep measures of how much I eat; and I am rather more, er, "ample" than I ought to be. Certainly, there may be a direct causation there.

Trouble is, there is also interesting evidence that folks who go on diets consisting overwhelmingly of such meat--bad plus good--lose weight! Hmm, how to factor that in?

Now, I would have ignored this article, as garden-variety sloppiness, until I read this:

"'This would be the Rolls Royce of studies on this topic,' said Barry M. Popkin, a professor of global nutrition at the University of North Carolina, who wrote an editorial accompanying the study. 'This is a slam-dunk to say that, "Yes, indeed, if people want to be healthy and live longer, consume less red and processed meat."'"

I suppose it's rather uppity of me to cross swords intellectually with Professor Popkin, but--wouldn't the "Rolls Royce" of a study such as this eliminate other variables, in order to demonstrate, clearly, cause-and-effect?

The Meat Institute ("boo! hiss! we know their agenda) makes the reasonable--but not devastating--observation that "the findings...were based on unreliable self-reporting by the study participants." Which--if such self-reporting is unreliable (I don't know if it is, but it seems that it might be), it might mean anything: the early-to-die folks might have eaten rather more meat than they wanted to report, or done other unhealthy things they didn't like to talk about, or overstated how much they exercise, etc. Or it might mean something else; or it might be that self-reporting is, in fact, as reliable as other tools. Might have been nice to have had a rejoinder to that point; but the Washington Post didn't expect anyone would take seriously what a trade group would say in, harumph!, obvious self-interest!

After that offensive interlude, the article takes us back to the voice of sweet, non-profit wisdom: the National Institutes of Health, AARP, and the Harvard School of Public Health! Surely we can trust them!

Now, sarcasm aside, I concede the study itself may well be more probative than is clear from the article; my criticism is directed against the article, and I am, yes, skeptical about just what the study does, and does not, demonstrate. We would all do well to be skeptical of such things, particularly as reported in the media.

But it was the final two paragraphs that caused me to chuckle knowingly, and write this post. Just tell me if you can see what it might have been:

In addition to the health benefits of reducing red meat consumption, a major reduction in meat consumption would probably have a host of other benefits to society: reducing water shortages and pollution, cutting energy consumption, and tamping down greenhouse gas emissions -- all of which are associated with large-scale livestock production.

"There's a big interplay between the global increase in animal food intake and the effects on climate change," Popkin said. "If we cut by a few ounces a day our red meat intake, we would have big impact on emissions and environmental degradation."

Nope, no political agenda there, is there?