30 Comments

www.overcomingbias.com - da best. Keep it going! GlenStef

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Then I got nothing

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Thanks for the link anyway.

I wanted to hear more about the stupidity of the medium IQ too.

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I think the standard survey by Gottfredson is "Why g matters" but that might not be the most direct answer.

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"how surprisingly stupid are the mid IQ"

Can you blog some on that, or maybe link to Gottfredson's talk, if available? This could shed some light on the practical meaning of IQ not just as a way of expressing relative ranking but rather in the context of absolute performance at tasks that a high-IQ person may deem important.

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Actually I was the last speaker.

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Garret Jones has written about just that:http://www.economist.com/bl...

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http://www.msnbc.msn.com/id...

The controversy over the eligibility of this athlete with congenitally defective lower legs is interesting re sports enhancements. Though he would doubtless be pretty fast on natural legs, his artificial legs seem rather likely to be better than the real thing.

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Viola, it has indeed been studied. But the controversy continues:Quitkin et al. (2000) assert that, in their analyses, the placebo response rate in studies using active placebos is similar to that using inert sugar pills (viz., about 30%). In contrast, Moncrieff and colleagues (2002) conducted a meta-analysis of available antidepressant trials using active placebos and found that the difference between antidepressants and active placebo was negligible, and was much smaller than in trials using inert placebos. Furthermore, unblinding still could not be ruled out entirely in the active placebo trials because of methodological limitations.

I haven't read that many meta-analyses on any subject, but I will say that I haven't seen meta-analysts comment very much about just what proportion of the analyzed literature they had examined prior to devising their inclusion criteria for the meta-analysis. This is relevant in obvious ways to the question of the objectivity of such meta-analyses. Of course if they are experts in the field they might have read a lot of that literature long before, over years or decades, and be rather aware of what sort of study design features correlate with certain results.

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Robin, leaky placebo blinding certainly does seem like the prime crux of the antidepressant effectiveness debate, at least to this casual reader on the subject. Has anyone ever tried a study with an active placebo producing dry mouth or whatever?

One could reduce de-blinding even more by limiting a study to subjects with IQ 90-95. Since this would not take us far from the population IQ mean, there would be little sacrifice of ecological validity, and it seems obvious that people under IQ 95 are less likely to de-blind themselves.

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On that front it's also important to remember that the aristocracy was always well-nourished, at all times from the beginning of history (and also relatively freer from infection, in case that also matters for IQ). Quite possibly little or no Flynn effect has occurred in the highest class. But that class has always been tiny, and its incremental IQ advantage over the next-best has never made any significant difference in population mean IQs.

This helps explain why Shakespeare, Newton, Euler, the high-medieval cathedrals, and the Book of Job rate highly by today's standards, despite the Flynn effect. Today, we certainly do have world-historical artists alive, at least in my opinion (see the best works of Arvo Part, Terrence Malick, Cormac McCarthy). But, if anything, we have fewer than you might expect when comparing today's population figures to those of 1850 or 1200 AD, or 500 BC

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You can find a similar effect by looking at raw IQ scores from many years ago. Were our great-grandparents really mentally retarded? (They were certainly *shorter* than people who live today...)

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So, is Linda's talk online?

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> IQ is about 70... Yet these people seem to be able to survive on their own

There is an explanation for this:

There are two types of retardation: familial and organic. The former is caused by normal population variation in intelligence while the latter is caused by diverse individual problems such as genetic defects or head injuries. Related to this, the IQ scores of people with familial retardation correlate normally with their parent and sibling's IQ scores (.50), while the IQ scores of people with organic retardation are not much associated with the IQs in their family.Retardation is measured by a combination of IQ and adaptive scales. Sometimes an IQ of 70 is used as the threshold of retardation. People with familial retardation and organic retardation of matched IQ perform the same in academic and training contexts, but organically retarded individuals do worse on the adaptive scales which measure things such as self-care, motor skills, and social functioning, signifying a broader range of mental dysfunction and some sort of developmental damage.

- "James Watson Tells the Inconvenient Truth: Faces the Consequences"

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See pp 367-9 in Jensen's "The g Factor" - one can read them for free on amazon.com.

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