Monday, September 28, 2015

How to Lie With Statistics Updated

How to Lie With Statistics is an old and good book on how not to be fooled by statistical tricks. I just came across one that, so far as I can remember (I read the book a long time ago) was not not included. 

Someone commenting on a Facebook global warming post put up this graph. Two comments later he wrote "Notice a trend?"

The trick, of course, is that the years are arranged in order of how hot they were. 2014 is at the right end not because it is the most recent year but because it was the hottest. 2012 is at the left end because it was the coolest of the years shown. Arranging them that way guarantees the appearance of a rising trend, whether temperatures are actually going up or down.

I am not certain that the person who put it up intended to imply that it showed a trend. He may have only meant that 2014 was hot and 2015 expected to be hot, as mentioned in his comment immediately after he put up the graph. But my guess is that either he had been fooled by the trick of drawing the graph that way or else he was deliberately trying to fool others.

I commented on it in the thread and will be interested to see his response.

Saturday, September 26, 2015

Hillary, Crichton, O'Rourke, Coulter and GKC

Scott on Slate Star Codex sometimes posts a collection of links with brief comments. I thought I would try it.


According to
Bloomberg, the FBI has succeeded in recovering some of the emails on the server that was supposedly wiped before handing it over to them. The reason this is a news story is that it might provide evidence against Hilary, emails that should have been turned over and were not because they contained information she did not want to get out. But whatever is on the server, the fact that the FBI was able to recover it is relevant to Hilary's qualifications to be president. Anyone living in the modern world and using computers should know that erasing a disk does not guarantee that the contents cannot be recovered. Even if she does not know much about computer technology, she ought to have people working for her who do. If she does not, that is evidence of incompetence, not in wiping a hard drive but in hiring and managing subordinates—a large part of a president's job.


Aliens Cause Global Warming is an essay by Michael Crichton on the way in which he believes that science has become corrupted in recent decades. The obvious application is to current climate controversies but the more general problem is what he views as a shift of the enterprise from the search for truth to a way of convincing people of things you want them to believe. His best example is probably the Nuclear Winter campaign:
The first announcement of nuclear winter appeared in an article by Sagan in the Sunday supplement, Parade. The very next day, a highly-publicized, high-profile conference on the long-term consequences of nuclear war was held in Washington, chaired by Carl Sagan and Paul Ehrlich, the most famous and media-savvy scientists of their generation. Sagan appeared on the Johnny Carson show 40 times. Ehrlich was on 25 times. Following the conference, there were press conferences, meetings with congressmen, and so on. The formal papers in Science came months later.
This is not the way science is done, it is the way products are sold. 
Part of the reason I agree with his point was an article I read at the time, written by one of the teams whose work fed into the nuclear winter conclusion. They conceded that a criticism that had been offered of their work was correct, concluded that fixing the error would reduce the length of nuclear winter from years to weeks. But they also found another mistake in their initial work with the opposite effect. Fixing that got it back to years.

There is nothing surprising or disturbing about the fact that published scientific articles sometimes have mistakes. I am currently in the middle of redoing an old project, my research on Icelandic law, and have concluded that at least some details in what I published more than thirty years ago were wrong. But there is a problem with proclaiming something as scientific fact before other people have had a chance to look at your research and critique it.

One interesting thing about that particular case is that it might be defended as a case of justified dishonesty. I can imagine a reasonable person deliberately misrepresenting the evidence, claiming it was much stronger than he believed it actually was, on the grounds that almost anything that reduced the risk of nuclear war, honest or dishonest, was worth doing. The counter-argument is implicit in Crichton's essay—that treating science in that way converts it from a mechanism for determining truth to a tool of partisan debate, with very bad long-term results.

A recent piece by P.J. O'Rourke takes Ann Coulter to task for tweeting during the September 16th debate:
Cruz, Huckabee Rubio all mentioned ISRAEL in their response to: “What will AMERICA look like after you are president.” 
How many f—ing Jews do these people think there are in the United States?
I am no fan of Coulter and enjoyed the essay, but with two reservations. The first has to do with the tweets. The reference to "f—ing Jews" is not about ethnicity. The implied point was that candidates focus on support for Israel to attract support from Jewish voters, and there aren't enough Jewish voters to make it worth doing. It is abrasively put, but it implies nothing about her view of Jews other than their numbers.

The point is, however, wrong—not because there are a lot of Jewish votes but because winning Jewish votes is not the reason the candidates talk about Israel. American conservatives are mostly pro-Israel for reasons that have nothing to do with their view of Jews, just as the American left is mostly anti-Israel for similar reasons. Republican candidates are trying to appeal to conservative voters; trumpeting their support for Israel is one way of doing so.

My other reservation had to do with O'Rourke's reference to Chesterton’s essay “The Problem of Zionism,” which implied that it was antisemitic. While it is possible to excerpt passages that sound antisemitic, it is also possible, perhaps  easier, to find ones that make Chesterton sound like a Zionist. For instance:
"It is our whole complaint against the Jew that he does not till the soil or toil with the spade; it is very hard on him to refuse him if he really says, 'Give me a soil and I will till it; give me a spade and I will use it.' It is our whole reason for distrusting him that he cannot really love any of the lands in which he wanders; it seems rather indefensible to be deaf to him if he really says, 'Give me a land and I will love it.'" 
For a more detailed discussion and defense of Chesterton, see the chapter on him in the second edition of my Machinery of Freedom.

Question: Would readers prefer it if I had posted this as three short posts instead of one long one?

CAGW and Consensus

Some years ago, Richard Tol published an article in the Journal of Economic Perspectives that pooled the work of everyone in the field to produce estimates of the net effect of various levels of warming, measured relative to pre-industrial temperatures. It included a graph showing estimated net cost, with an error range. The green lines show his results after correcting some errors in the original paper.

The solid green line shows the estimate. It is positive up to about two degrees, negative thereafter. The dashed lines are the boundaries of the 95% range. The high end (optimistic) does not go negative until 3°C.

What about the low end? At 3°C, the welfare impact is a reduction of 10%. The IPCC high emissions scenario, RCP8.5, which gets us to that temperature sometime in the second half of the century, assumes continued economic growth. If so, the 10% reduction in welfare due to AGW will be combined with an increase several times that large.

My previous post discussed an article in the Journal of the National Academy of Sciences which criticized the IPCC models and concluded that warming due to AGW had been reasonably stable for the past century at a little less than one degree/century. If that continues, by 2100 global temperature will be less than two degrees above its preindustrial level. On Tol's estimate, we will be better off than if there had been no AGW, worse off than if AGW had been a little slower. 

If, on the other hand, we accept RCP8.5, when we reach the 3° mark we will be worse off than if warming had not occurred, better off than we are now—even if we take the low end of Tol's predicted range of effects.

Which I think is an adequate response to people who tell me that to deny catastrophic effects of warming is to ignore the scientific consensus.

Friday, September 25, 2015

Modafinal, Steroids, and Competition

A recent discussion of a post on my favorite blog dealt with the implications of smart drugs, in particular modafinil. A number of people argued that the problem with permitting such things was competition. If one person uses them, others have to use them in order to compete with him, so you end up with whatever negative side effects the drugs have—modafinil does not seem to have many, but nobody knows for sure—and everyone in the same position as before.

That argument views economic competition as something like a football game, where one side wins and the other side loses—if you are not the best you are nothing. If that were true, most of the population of the world would be unemployed. Even without smart drugs, people vary in how able they are—they cannot all be the best.

Suppose the use of modafinal makes me 10% better at whatever I do. The result is not that someone with the same abilities who does not take it is useless, merely that I am ten percent more useful and so can expect an income about ten percent higher, whether my salary as an employee or my earnings if I am self-employed. I can decide for myself whether the additional income, or the additional leisure if I choose to work fewer hours instead of making more money, is worth whatever I think the risks of side effects are. If many people use smart drugs, some of the benefit might to go to other people either as lower prices for what the more productive workers produce or higher returns on other inputs to production. But somebody still gets the benefit of the additional productivity.

The source of the mistaken intuition is probably the analogous case of steroids in sports. There the right answer is less clear, depending on what it is that athletes produce. If what the fans care about is only relative ability, whether or not their team can beat the other team, then if everyone uses steroids the players are worse off—assuming significant negative side effects—and the fans no better off. If fans value absolute quality, enjoy watching athletes more the better they are, then the argument I have offered applies to that case as well. 

Not being a sports fan, I cannot offer an informed opinion on which is the case.

The same confusion between economic competition and sports competition shows up in one of George Orwell's mistakes. In a very interesting joint review of The Road to Serfdom and a  book by Konni Zilliacus, a left wing Labor politician, he wrote:
The trouble with competitions is that somebody wins them. Professor Hayek denies that free capitalism necessarily leads to monopoly, but in practice that is where it has led ...
Which, fortunately, is not true.

[An earlier discussion of the same issues, not in the context of smart drugs]

Sunday, September 20, 2015

An Explanation for the Pattern of Warming

I have been arguing for some time that what the pattern of global warming suggests is a rising trend due to AGW with an alternating trend from some other cause superimposed on it, the latter having a period of about sixty years. On that interpretation, the period of stable to slightly falling temperatures from about 1940 to 1970 and the period of roughly stable temperatures from 2002 on represent periods when the two trends were pushing in opposite directions and so roughly canceling each other, the rapid warming from about 1910 to 1940 and 1970 to 2002 periods when they were reinforcing each other.

The conventional explanation for the mid-century pause is that it was due to aerosols producing a temporary cooling effect. That became less plausible, at least to me, when the pause reappeared, roughly on schedule. If I am correct, the IPCC models, by special casing the earlier pause instead of treating it as part of a recurring pattern, overestimated the average rate of warming, treating periods when the two trends reinforced as if they were the norm, the period when they canceled as a special case.

I have now come across an article in the Proceedings of the National Academy of Sciences that supports my interpretation of the pattern, based on analysis of the 353 year Central England Temperature Series, the longest instrumental temperature record that exists. The authors conclude that there is a recurrent multidecadal oscillation with a period of about seventy years, likely due to the Atlantic Multidecadal Oscillation. They reject the aerosol explanation and conclude that:
The underlying net anthropogenic warming rate in the industrial era is found to have been steady since 1910 at 0.07–0.08 °C/decade, with superimposed AMO-related ups and downs that included the early 20th century warming, the cooling of the 1960s and 1970s, the accelerated warming of the 1980s and 1990s, and the recent slowing of the warming rates.
Almost precisely my conjecture—I slightly underestimated the period of the oscillation—with an explanation and a lot more data.

Friday, September 18, 2015

If Obama is a Muslim, He is a Very Bad One

Various people, including Donald Trump, have suggested that Obama was not born in the U.S. and may be a Muslim. The former claim, while it may be false, is not absurd—there is no obvious way of being certain of the details of the birth more than fifty years ago of someone of no particular prominence. The claim he is a Muslim, on the other hand, has at least two serious problems. 

One of the binding obligations of Islam is to pray five times a day, in a specified manner (with some possible variations), at specified times. If Obama has managed to do that through most of two terms without anyone noticing, he is a very talented man. A second binding obligation is to fast through the month of Ramadan—neither eat nor drink in daylight hours.

Thursday, September 17, 2015

Did Ahmed Make a Clock?

Speaking at an afternoon news conference outside the family’s home, Ahmed’s father said he’s proud of his son and wowed by his skills.
“He fixed my phone, my car, my computer,” Mohamed Elhassan Mohamed said. “He is a very smart, brilliant kid.”
Public discussion of the case centers on whether or not the school and the police unreasonably over reacted. As best I can tell the answer is that they did. But what interests me is an entirely different question. A central feature of the story is how talented Ahmed is, a fourteen year old engineering marvel. That makes it a better story, better for the news media and better for Ahmed. But is it true?

One commenter on a blog I read, looking at the picture of what he brought into school, concluded that what it was was an old clock the innards of which Ahmed had taken out of its case and transferred to a briefcase. I do not know enough about electronics to offer an intelligent guess as to whether he was right, but it seems plausible enough—and well within the ability of a fourteen year old. 
If so, this is not only about school officials over reacting. It's also about the willingness of the media to tell a good story without any serious effort to find out if it is true.

P.S. A fairly detailed analysis of what the clock was: