Does watching TV cause autism?

I have no idea, but two gentlemen from the Johnson School of Management at Cornell and one from the Economics department at Purdue seem to think so. They have written…
Posted inStatistics

Next prohibition: salt

Here is a question I added to my chapter on logic today.

New York City “Health Czar” Thomas Frieden (D), who successfully banned smoking and trans fat in restaurants and who now wants to add salt to the list, said in an issue of Circulation: Cardiovascular Quality and Outcomes that “cardiovascular disease is the leading cause of death in the United States.” Describe why no government or no person, no matter the purity of their hearts, can ever eliminate the leading cause of death.

I’ll answer that in a moment. First, Frieden is engaged in yet another attempt by the government to increase control over your life. Their reasoning goes “You are not smart enough to avoid foods which we claim—without error—are bad for you. Therefore, we shall regulate or ban such foods and save you from making decisions for yourself. There are some choices you should not be allowed to make.”

The New York Sun reports on this in today’s paper (better click on that link fast, because today could be the last day of that paper).

“We’ve done some health education on salt, but the fact is that it’s in food and it’s almost impossible for someone to get it out,” Dr. Frieden said. “Really, this is something that requires an industry-wide response and preferably a national response.”…”Processed and restaurant foods account for 77% of salt consumption, so it is nearly impossible for consumers to greatly reduce their own salt intake,” they wrote. Similarly, regarding sugar, they wrote: “Reversing the increasing intake of sugar is central to limiting calories, but governments have not done enough to address this threat.”

Get that? It’s nearly impossible for “consumers” (they mean people) to regulate their own salt intake. “Consumers” are being duped and controlled by powers greater than themselves, they are being forced to eat more salt than they want. But, lo! There is salvation in building a larger government! If that isn’t a fair interpretation of the authors’ views, then I’ll (again) eat my hat.

The impetus for Frieden’s latest passion is noticing that salt (sodium) is correlated—but not perfectly predictive of, it should be emphasized—with cardiovascular disease, namely high blood pressure (HBP). This correlation makes physical sense, at least. However, because sodium is only correlated with HBP, it means that for some people average salt intake is harmless or even helpful (Samuel Mann, a physician at Cornell, even states this).

What is strange is that, even by Frieden’s own estimate (from the Circulation paper), the rate of hypertension in NYC is four percentage points lower than the rest of the nation! NYC is about 26%, the rest of you are at about 30% If these estimates are accurate, it means New York City residents are doing better than non residents. This would argue that we should mandate non-city companies should emulate the practices of restaurants and food processors that serve the city. It in no way follows that we should burden city businesses with more regulation.

Sanity check:

[E]xecutive vice president of the New York State Restaurant Association, Charles Hunt…said any efforts to limit salt consumption should take place at home, as only about 25% of meals are consumed outside the home.

“I’m concerned in that they have a tendency to try to blame all these health problems on restaurants…This nanny state that has been hinted about, or even partially created, where the government agencies start telling people what they should and shouldn’t eat, when they start telling restaurants they need to take on that role, we think its beyond the purview of government,” Mr. Hunt said.

Amen, Mr Hunt. It just goes to show you why creators and users of statistics have such a bad reputation. Even when the results are dead against you, it is still possible to claim what you want to claim. It’s even worse here, because it isn’t even clear what the results are. By that I mean, the statements made by Frieden and other physicians are much more certain than they should be given the results of his paper. Readers of this blog will not find that unusual.

What follows is a brief but technical description of the Circulation paper (and homework answer). Interested readers can click on.

Posted inFun

I’m thinking of turning to crime

He is a man of good birth and excellent education, endowed by nature with a phenomenal mathematical faculty. At the age of twenty-one he wrote A Treatise on the Binomial…
Posted inFun

A new movie rating scheme

Most newspapers rate movies on the star system. Four to five stars are printed, and from none to all of them are colored in. Supposedly, the more stars colored, the…

Dahn-Yoga Touted “Peer-Reviewed Study” Stinks

I have been asked to write this review by a party who wishes to remain anonymous because of the fear of reprisal. See this article for background. Also this.

Dahn yoga might not be of interest to you, but this review is larger than that. It will show you how easy it is to publish material in a well known journal that is poor at best. Civilians are often shocked to discover that peer-review is only a weak indicator of correctness. This article removes some of that mystique.

This article is long, but has to be.

Study Abstract

Sung Lee, an internist, while at the Weill Cornell Medical School, conducted an experiment of Dahn yoga. He published the results in the paper: Prospective Study of New Participants in a Community-based Mind-body Training Program. It appeared in the Journal of General Internal Medicine, 2004 July; 19(7): 760–765.

This study has been touted by Dahn sympathizers: Ilchi Lee (Dahn founder) boasts of it (pdf), TV broadcasts (Sung Lee’s picture is in the upper-right corner), as supportive research, chiropractors in Sedona, and fan sites of Dahn.

Lee went to several locations in New York City and recruited people to join a three-month Dahn (introductory) program. All of these people self-selected themselves into the program; they came seeking yoga; all were new to Dahn. All were asked, at the beginning and end of the study, a series of questions.

The main ones were from the SF-36, a standard questionnaire. The most useful SF-36 “item” is question 1: “In general, would you say your health is: Excellent (5)…Poor (1)?”1 Another is, “Have you been a very nervous person? (6) – (1)” This “instrument” is divided into domains, such as “vitality” and “mental health,” which are simple functions of the questions. The “nervous” question is part of the mental health domain. Another is, “Have you felt downhearted and blue? (6) – (1)”

Papers which use the SF-36 rarely show the questions; they are content to report on the domains. Seeing the exact questions makes them sound far less impressive than when stated in their usual academese. For example, Lee calls the SF-36 “a validated health assessment instrument.”

Averages of the US population of each of the domains exist. The participants in the Dahn study began with scores lower than the US average: a fact which is not surprising, considering these were people who were newly arrived for exercise training.

There was no control group: all received the Dahn training. 194 started, and 171 completed the study. Three out of four were women. Five of the 171 reported an injury due to the training: it is unknown how many of the twenty-three who dropped out were injured.

From the abstract: “New participants in a community-based mind-body training program reported poor health-related quality of life at baseline and moderate improvements after 3 months of practice.” This means that several of the people had small increases in their three-month SF-36 scores.

That is, some people went from answering “A good bit of the time” to “A little of the time” on the question “Have you been a very nervous person?” And so on for some of the other questions.

From this, Lee was able to say that “Dahn worked.” Actually, the best that could be said was “Dahn didn’t cause too much harm.” Here’s why.

Specific objections

I was at Cornell at the time Lee was completing, presenting, and writing up his study. I made my objections known at that time. You must also understand that in academics “A paper is a paper”, and nearly anything can be published in some peer-reviewed journal somewhere. Because of this, the number of journals is staggering: they increase constantly.