Has a statistician demolished the idea of a single general intelligence factor?

Cosma Shalizi is a rather egotistical-sounding young man of apparently Afghan ancestry. He is also an assistant professor in the Department of Statistics at Carnegie Mellon University in Pittsburgh. On his blog, Three Toed Sloth, he has a long post demonstrating that a popular form of mathematical analysis generically called factor analysis cannot be used to demonstrate the existence of IQ (or 'g' as we psychometricans call it).

His criticisms are perfectly correct. Factor analysis cannot prove ANYTHING in fact. It is just a convenient but rather arbitrary way of summarizing a set of correlations. Factor analysis is such a weak technique that I myself in my more than 200 published academic papers have used it only rarely -- even though I normally present my research results in correlational form. It is my rather severe view that most (though not all) theories in psychology can be substantiated or dismissed with just one Pearsonian correlation coefficient. Anything else tends to suggest poor research design to me. (Yes. I do know about non-linear relationships. I tested for one such in my very first dissertation, in fact).

The sloth is also correct in saying that much of the research into IQ has used factor analysis as a way of summarizing findings. That the findings are not DEPENDANT on that descriptive technique is the point he appears to overlook.

The underlying finding for 100 years or more is that ability to solve one sort of puzzle generalizes strongly to the ability to solve other quite different sorts of puzzle. Problem solving ability is general, no matter how you choose to summarize that. And problem-solving ability is what IQ or 'g' measures.

Perhaps the biggest surprise is that verbal ability (as indexed -- say -- by the number of rare words understood) correlates well with mathematical ability (as indexed -- say -- by ability to detect complex numerical sequences). This is despite the fact that many people report being good in only one of those areas. I am in fact one of those who are good with words but shaky with mathematics. Yet I did for some years teach statistics at a major university. I obviously had some mathematical ability despite my discomfort with the subject. And it is the genes too. My son now teaches mathematics at another major university. And at school he was always a couple of years ahead of his class in reading ability too. Pesky stuff, that IQ.

The sloth should rise above his fascination with mathematical processes and focus on the underlying reality.

There is another over-enthusiastic blog here that claims that the sloth "offers an exhaustive demolition of the idea of a single general intelligence factor". The blogger apparently believes that the sloth has magically made lots of large correlation coefficients disappear. One of the commenters on that blog made an excellent point in addressing the common allegation that IQ tests measure only the ability to pass IQ tests. He said:

"If IQ tests are worthless, then so are college degrees. What do they really measure other than the ability to pass college classes? Nothing. Maybe we should assign MDs by lottery as well. I'll let you go first on the triple bypass surgery under your new world order."

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ELSEWHERE

U.S. Forces Could Attack Iran if Needed: "While military action against Iran is a last resort, the U.S. has the resources to attack if needed despite the strains of wars in Iraq and Afghanistan, the top U.S. military officer said Thursday. Navy Adm. Michael Mullen, the chairman of the Joint Chiefs of Staff, said the focus now is on diplomacy to stem Iran's nuclear ambitions and its support for insurgents in Iraq. But, he told reporters, "there is more than enough reserve to respond (militarily) if that, in fact, is what the national leadership wanted to do."

Fact-free Leftist illusions: "The alternative Western view of Middle East strategy--so influential in academic, media, and to some extent diplomatic circles-has a six-point program that boils down as: Make deals with Iran, Syria, Hamas, and Hizballah; ally with Muslim Brotherhoods; and split Iran and Syria. Those more extreme who advocate this approach are sympathetic to these forces, seeing them as more misunderstood victim than aggressive oppressor; the more moderate among them merely think the radicals can be moderated through concessions and confidence-building measures. In other words, they are not really adversaries but either already good guys or can be converted into playing that role. By this analysis, those who claim these radical regimes and movements are dangerous due to their radical ideology, violent methods, and totalitarian goals are standing in the way of solving issues quickly, painlessly, and peacefully. They are warmongers perpetrating needless conflicts. This analysis generates tremendous anger against the United States and Israel or anyone else who tries to explain that this approach will not work. Through this transformation, those who generate grievances that create terrorists or don't want to give in to the terrorists' demands are the real villains"

Cardinal signals firm Vatican stance with Muslims: "The top Vatican official for Islam has praised a novel Muslim call for dialogue but said real theological debate with them was difficult as they saw the Koran as the literal word of God and would not discuss it in depth..... The fact that Muslims can build mosques in Europe while many Islamic states limit or ban church building cannot be ignored, he said. "In a dialogue among believers, it is fundamental to say what is good for one is good for the other," he said."

Media can distort anything into anti-capitalism: "Financial Times columnist Clive Crook has had it. Reading MSM's take on the recent World Economic Outlook published by the IMF he feels like the characters of Ayn Rand's Atlas Shrugged. No, he is NOT a right wing conservative. He writes for the Atlantic Magazine and National Journal. It is just that he knows enough about economics to finally get what she got 50 years ago - Capitalism is moral and technological innovators are vilified heroes who actually make the world better. The opposite is true of anti-Capitalists, be they from the right or from the left"

Foolish optimism: "The Bush administration's plans to convene a new round of Israeli-Arab diplomacy on Nov. 26 will, I predict, do substantial damage to American and Israeli interests. As a rule, successful negotiations require a common aim; in management-labor talks, for example, both sides want to get back to work. When a shared premise is lacking, not only do negotiations usually fail, but they usually do more harm than good. Such is the case in the forthcoming Annapolis, Maryland, talks. One side (Israel) seeks peaceful coexistence while the other (the Arabs) seeks to eliminate its negotiating partner, as evidenced by its violent actions, its voting patterns, replies to polls, political rhetoric, media messages, school textbooks, mosque sermons, wall graffiti, and much else. Damage will be done should the Israeli government make "painful concessions" and get a cold peace or empty promises in return, as has consistently been the case since 1979. This lop-sided outcome would, once again, boost Arab exhilaration and determination to eliminate the Jewish state."

For more postings from me, see TONGUE-TIED, EDUCATION WATCH INTERNATIONAL, GREENIE WATCH, POLITICAL CORRECTNESS WATCH, GUN WATCH, SOCIALIZED MEDICINE, FOOD & HEALTH SKEPTIC, AUSTRALIAN POLITICS, IMMIGRATION WATCH INTERNATIONAL and EYE ON BRITAIN.

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