Monday, October 06, 2008

Lynn and Vanhanen data not perfect, but best, most comprehensive available

In a previous post looking at the relationship between a country's average intelligence and the ideal age advantage of men in the eyes of the country's women, Agnostic wonders if there aren't more reliable sources for IQ data than Lynn and Vanhanen. Specifically, he points to some digging by Dienekes that seems to show Lynn inexplicably adjusted Greek IQ downard a couple of points in one of the two samples used to compute the nation's average. Dienekes argues that the other result L&V use (showing an average IQ of 87) should be given little weight because it was conducted in 1961 on 9-14 year olds before universal education had been adopted in Greece.

Other aptitude testing results lend credence to the L&V estimate, however. The Programme for International Assessment (PISA), tests 15 year-olds every three years in the areas of reading, math, and science. PISA results convereted to IQ scores on a scale with a 15-point standard deviation puts Greece at 91 in '06, one point lower than L&V's estimate. In '03, PISA scores suggested an IQ of 92, identical to L&V's most recent data, so large fluctuations don't appear to offer an explanation.

L&V's numbers hold up pretty well against PISA results. For the 50 countries where both L&V and PISA estimates are available for '06, the correlation between the two is a statistically significant .81 (p=0). This relationship is similar to the relationships found between the figures Lynn lays out in Race Differences in Intelligence (p173-175) and the International Studies of Achievement in Mathematics and Science, for which 52 countries provide results. Lynn's estimates correlate with these scores in the range of .81-.89, depending on the year and subject of the test.

Unfortunately, these tests only extend to OECD countries and a handful of middling countries that are trying to get in, like Russia and Brazil. L&V's estimates allow for far more extensive international correlations to be searched for.

GNXP's Jason Malloy suggested I look to a site by Volkmar Weiss for additional numbers from German professor Heiner Rindermann, who composed his own estimates by combining L&V estimates with results from PISA, PIRLS (a reading assessment), and TIMSS. I'm not sure where Rindermann's numbers come from for many third-world countries, as only around 50 or 60 mostly developed countries participate in them, but I may be missing something (the paper is not open access). Whatever his methodology, these results correlate at .94 (p=0) with V&H's estimates. That would be more telling if I knew how much weight Rindermann gave to V&H's data in coming up with his estimates, but they're essentially interchangeable regardless.

Weiss makes the case that the small variances between L&V and PISA suggest the existence of dysgenic effects in some countries*. His assertion is based on the differing periods of time the respective tests are measuring. L&V are using figures derived from people who are today somewhere between midlife crisis and the grave. PISA and others like the aforementioned PIRLS or TIMSS, in contrast, are looking at contemporary teenagers. I've suggested something similar may be happening in the US, specifically in the Southwest, where estimates several decades old vary most greatly with contemporary estimates based on NAEP scores (they are stable over time in the rest of the country).

Given their consistent relationship with other international testing results, the L&V estimates remain among the most thorough and wide-ranging available, so I'll continue to use them.

I could substitute Rindermann's figures, which are as expansive as L&V's are, but the extremely low values given to sub-Saharan Africa make me less comfortable with their reliability. For example, Sierra Leone is given a 59, and that's with L&V's 63 pulling it up to some extent. If L&V are given half weight, that'd mean the other tests put the country's average at an almost unheard of 55 (that'd put the average Sierra Leonean at about the 0.1 percentile in the US). Somalia strains credulity to the greatest extent of all. L&V put it at 84 to Rindermann's 58. At a half-weight, that's 32 (!) from non-L&V data. Even at one-fourth weight, it's only 51.

At almost non-existent levels of education in many of African countries, scholastic aptitude tests are probably going to tend to understate actual IQ relative to tests like Raven Progressive Matrices. Anyway, I see no compelling reason to assume Rindermann's are necessarily superior. I suppose I could run both sets to try to better distill real relationships, but as we're looking at estimates not absolutely precise values, and they are already so similar, that won't add much value.

The data are here.

* Among those said to be undergoing dysgenic changes in average intelligence: Hungary, Luxembourg, Germany, Greece, Poland, Spain, Italy, the US, and Mexico.


Stopped Clock said...

You can look at the Somalia data and wonder why Rindermann placed them so low, or you can look at it the other way and wonder why L&V's book placed them so high. 84 is pretty high for sub-Saharan Africa ... heck, they even beat Egypt!! I'm sorry but I have to take this as more evidence that we just don't have very good information for the average intelligence of most Third World countries. I cannot believe that there is a 21 point IQ gap between Somalia and Ethiopia.

BGC said...

Because IQ is an ordinal scale, not a ratio scale, it is hard to know what is credible and what is not. I don't find any of theses estimates literally incredible, since we don't know enough about distributions of IQ in genetically different groups.

Look at the recent data on pygmies - summarized at

Some pygmies reach sexual maturity age 12 and have an average life expectancy of 24. Yet the authors assert (in the papers from which this report comes) that pygmies probably have the same intelligence as humans of normal stature. That I _do_ find incredible. (i.e. that a human brain of 'normal' intelligence can be grown in 3/4 of the time - 12 instead of 16 years).

Nobody is now doing international IQ surveys (which would be quite straightforward nowadays). Such a study could easily refute L&V if they are wrong. But of course there is the serious possibility that such a study would confirm L&V...

Indeed, nobody is even doing national IQ surveys (nothing in the UK since Lynn's estimations of 32 years ago).

Nobody is even surveying comparative IQ in colleges (so we don't know precisely the effects of educational expansion). Nobody is even using IQ to discover the effect of education and which education system is best (which is what Rindermann is arguing for).

Do you ever get the feeling that there are forces at work who don't want to know about IQ differences - I mean who really really don't want to know?

The resulting paucity of directly-measured IQ information and lack of replication makes it easy to maintain a pretence of being scientific, while on principle rejecting inconvenient IQ-based arguments by endless and richly-imaginative methodological nit-picking.

al fin said...

IQ and genetics are like the two components of a binary toxin. Mix them, and you are dead--as far as contemporary political correctness in leftist dominated academics and popular culture are concerned.

bgc: nobody in the funding agencies and foundations wants to know the answers that AE etc. are asking. Their motto: "better not to know."

Under Obama, this phenomenon of runaway PC can only get worse. Anyone who tries to oppose it must face the Thought Police.

Peter said...

When I looked at the Swivel link I stopped on the very first line and thought something was very odd. PISA reports an average IQ of only 80 for Argentina, a country with a largely European-descended population. That can't be right.

Audacious Epigone said...


As BGC says, it's certainly not perfect. That's discouraging on one hand--it really shouldn't be that difficult for accurate, standardized results to be produced. A joint effort by universities in multiple continents could easily (logistically that is, not politically) pull it off. On the other hand, that the data aren't perfect and yet we see so many robust correlations with quality of life factors suggests that the true relationships are even stronger than what is presumed.


From those Rindermann papers (thanks again!), I see that there is no uniform weight for L&V--the more copious the data from scholastic tests, the less L&V factors in. What do you think of the presumed 5 point docking of countries without L&V data? That strikes me as too arbitrary a change, especially since he's still using the other tests to get an aggregate score (thus weakening the overall correlation between the various scholastic tests and L&V).


I'm sure you've seen it, but for those who have not, here is Godless Capitalist's argument that an Obama/Biden Presidency would be bad for flushing out HBD realities.


Yes, that does seem low. I wonder what Argentina's school attendance rates are. Rindermann docks points as the percentage of students participating in scholastic tests drops.

Stopped Clock said...

Totally worthless personal anecdote: my Spanish teacher in 8th grade told me "if this was Argentina, you'd all be working in gas stations by now." (And that wasnt meant as insult, as far as I could tell.)

Also, while I basically agree about the Pygmies probably having lower IQs than other Africans, isn't brain growth pretty much unrelated to sexual maturation? I mean, the age of the onset of puberty has been getting lower and lower over the past few hundred years, but our brains aren't maturing any faster, as far as I know.

(Also, this may or may not be relevant, but: one of my textbooks says that the brain reaches 95% of its adult size by age ten, and that the remaining growth (which can take more than ten years) is mostly in areas of the brain responsible for emotion rather than cognition; however a 10 year old is not, generally speaking, the intellectual equal of an adult because there is still a lot of development going on ... but, as I said, little or no actual literal growth in the brain actually takes place after age 10, so even if physical growth were to stop very early, such that the brain had no room to grow anymore, all of those processes which normally take place after age 10 could still take place because they apparently don't require the brain to increase in size. Which is why, I imagine, midgets are not generally known to be mentally retaƕded.)

al fin said...

Thinking of IQ as mental age may explain how low-IQ populations in Africa and South America can function fairly well in primitive societies.

They are not disabled as long as they are not required to maintain a high tech society, and keep the power flowing and planes flying.

Of course with Pelosi, Boxer, Reid, Salazar etc. trying to choke off energy supplies to the US, even a semi-intelligent population can behave like a troupe of shrieking monkeys, if ideologically predisposed to do so.

Jason Malloy said...

GNXP's Jason Malloy suggested I look to a site by Volkmar Weiss for additional numbers from German professor Heiner Rindermann... I'm not sure where Rindermann's numbers come from...

I'm sorry, I just did that for a quick link. Rindermann's actual 2007 paper -- which explains his methods -- has always been available in the gnxp forum, as noted in the Watson post. It is also available on Rindermann's website (PDF).

For an independent look at African IQ scores, see here. I'll send it to you.

Steve Sailer said...

Lynn is not as young as he used to be, and I've noticed now and then what appear to be occasional clerical errors in his numbers. That's another reason people shouldn't get worked up about individual country scores from L&V. There are only a few countries where there is so much data (e.g., Japan) that you can feel really confident about that one country's score.

Instead, look at the big picture, the overall patterns. Over a half dozen years now, L&V's data have held up very well for those purposes.

Audacious Epigone said...


Thanks for both. BGC sent me the same, but I skimmed too carelessly at first and didn't catch that Rindermann gives L&V one-third weight:

"I calculated one total score for all cognitive ability studies (IQ, student assessment studies). Student assessment studies were given a double weight in this total because they have newer and larger samples and they consist of more cross-national studies."

I think Weiss made some major transcription errors, or I'm missing something. For Somalia, for example, Rindermann doesn't report any student assessment scores at all and assigns an adjusted IQ of 68 to the country. Weiss shows him reporting a 58 and V&H reporting an 84. But in IQ and Global Inequality, L&V give Somalia 68 (I'm not sure what they estimated for Somalia in IQ and Wealth of Nations, which is where Weiss gets his V&H numbers, but such an enormous gap strikes me as impossible, since in both cases Somalia was being estimated from surrounding countries).

I'm going to run the numbers again using different sources, and report the same relationships as I did in this post. Skimming through some more, I see several others instances of where Weiss' numbers for Rindermann don't match the actual numbers Rindermann gives.