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.

If you weren’t worried before, then take a look at this shocking new climate forecast!

No, only kidding. This is the real forecast:

Sorry. Can’t help myself. Here are four more “forecasts”.

Each of the “forecasts” were generated by what is called a “random walk.” Here is what that is. Grab a coin and go out and stand on a corner of some sidewalk that stretches for a long way in both directions. Call one direction “positive” and the other “negative”. The corner you start at will be called “zero”. Flip your coin: If it is heads, then take one step forward toward positive; if tails, then take one backward toward negative. Keep doing this for a long time and soon you will find…that your neighbors think you are crazy.

But that’s a random walk. If you do the coin flips and steps for a long enough time, you’ll find that you spend a heck of lot more time than you might have guessed on either the positive or the negative side. You will probably find that, when you quit, you are way up along the positive side, or way down along the negative. This is true even though the average of those coin flips, the +1s and -1s that make up your steps, is pretty near 0; and even though the average goes to 0 the longer you flip the coin.

The “climate model forecasts” generated above were done so by reference to a paper by A.H. Gordon, available here, called “Global Warming as a Manifestation of a Random Walk”. It is a very readable paper that bears attention.

Gordon proposed that a climate could be made by generating random “shocks” to a climate system. What’s that? Well, imagine the climate is going along peacefully, maintaining its temperature and minding it’s own business, when suddenly—bame!—some external force causes it to change its temperature up or down. An external force might be a change in the Earth’s orbit, or a shifting in cloud cover, or a flock of birds flying this way or that, or anything. This shock persists in the system for some time; little shocks build up and over the course of a year the climate—the mean temperature—changes. It is just as likely for this random-walk climate’s temperature to go up as it is to go down,.

Random walks have some surprising properties which, by virtue of being surprising, are not intuitive. The first is that we’d expect adding random ups and downs (1s and -1s) together would get us a bunch of no changes (or 0s). We don’t get 0s, but numbers which travel far from 0 as time goes on. In fact, it can be shown—via something called the arcsine law—that it’s more probable that this climate will be at an extreme value whenever the series stops, and will not be near 0. The pictures show this.

What about the real climate, the one we actually live in? It’s certainly true that the real climate experiences external shocks of every kind. Gordon found (over the period he looked and with one particular, often used data set) that temperatures went up about just as many times as it went down, just like what would be expected in a random walk climate. He found that the value of the temperature at the end of the series he had was an extreme one, just like we would be expect in a random walk climate. He made a lot of pictures, like we have, and noticed that a lot of them look just like our real climate.

The pictures that make up our and Gordon’s “arcsine forecast”, for technical reasons, aren’t 1s and -1s, but numbers simulated from a normal distribution with a central parameter of 0, which means the numbers are equally likely to be above 0 as below 0 just like in the -1/+1 random walk, but here they can be any number greater or less than 0 (the standard deviation parameter, for those who know of such things, is set at 0.12, which is the same as the estimated standard deviation parameter for actual global mean temperature; see Gordon’s paper for a fuller description).

What does all this say about the real climate? That it happens to look just like a bunch of random numbers. Gordon cautions, “That is not to say that the temperature record is a random walk, but that it does possess similar features.” The surface temperature records “also exhibits properties of the arc-sine law. It is concluded that the global series could have arisen from random fluctuations and could therefore be analogous to arc-sine law governed by random walks.”

This means the climate we have might be less controllable than we thought it was (controllable negatively or positively through man’s activities).

He ends with some sage advice:

It is important to examine all ways and means by which the observed data series develop trends before facing hard and fast conclusions that any particular activity is the one and only responsible agent.

Below is the code where you can generate your own arcsine climate model forecast in R: