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September 23, 2003

IQ comments

Some comments on my post More Census Gleanings may have got lost in the site changeover. Please repost any comments and questions and I will try to reply.

One of my replies that got lost was about the IQ of ‘Blacks’ in Britain. My post said that the Black-White differential was less than in the US, but this was questioned.

First, it should go without saying that there is no such thing as the IQ of a population. There is just the average score of a population on particular tests. The results of particular tests tend to correlate together, but a difference of 5 points or so in the population mean on different tests would not be unusual.

In my comments on the Black-White differential in Britain I was relying mainly on the following:
[1] Nicholas Mackintosh, IQ and Human Intelligence, OUP, 1998
[2] A. West, C. Mascie-Taylor, and N. Mackintosh, Cognitive and educational attainment in different ethnic groups, J. Biosocial Science, 1992, 24, 539-554
[3] N Mackintosh and C. Mascie-Taylor, The IQ question (1986), appendix to an official report on ethnic minority education in Britain.

The gist of the various studies, summarised in [1], is that early studies (1960s and early 70s) on Blacks in Britain tended to show average IQ around 85 (with Whites around 100): a similar differential to the US. However, the samples included very recent immigrants, and when these were stripped out, the gap was narrower. More recent studies (1980s onward) have shown a further narrowing of the gap. Notably, the Child Health and Education Study (1980) shows a difference of only about 5 points on non-verbal tests and 9 points on verbal tests.

There is a potential pitfall in making comparisons over time if the meaning of ‘Black’ is changing. Most obviously, there has been a large increase in the proportion of mixed-race children. However, this pitfall appears to be avoided in reference [2], where children with parents from different ethnic groups were excluded from the study. In this study West Indian (Black Caribbean) children aged 7 to 15 had mean scores between .24 and .77 standard deviations below the White British control group, varying according to age group, the average over all age groups being about .5 s.d., equivalent to about 8 IQ points.

If anyone knows of a reputable recent study that shows a differential of more than 10 IQ points (about 2/3 of a standard deviation), I would be interested to know. Also, do American readers know of any data on Black Caribbean immigrants to the US? They have the reputation of doing better, both educationally and economically, than American blacks, but I don’t know of any IQ data.

Posted by David B at 04:10 AM




It turns out my home computer still hasn't figured out the whole server change yet, so I was able to recover your comments along with some others.

Posted by: Jason Malloy at September 23, 2003 06:17 AM


David:

If the objective of comparative studies of intelligence across racial or ethnic groups is to establish the 'average' intelligence of such groups, I'm wondering how useful it is to compare immigrant groups versus an indigenous population.

Immigrants to (say) Britain are generally held to having been self-selected as the most capable, enterprising and so on of a particular ethnic group from a particular country. Logically that would suggest that such immigrants would tend to fall on the right-hand side of their original group's bell curve.

It would seem to me that that a more useful comparison is between indigenous populations (say England and Jamaica) than between one indigenous population and another cognitive elite. I think the former is the approach taken by Lynn and Vanhanen, which does not as yet appeared to have received a convincing scientific rebuttal.

Posted by: PhilT at September 23, 2003 09:18 AM


It would seem to me that that a more useful comparison is between indigenous populations (say England and Jamaica) than between one indigenous population and another cognitive elite.

these all have issues because components are confounded together-obviously, the environment is very different in jamaica than in england. and of course, there is the problem you mention about immigrants in a british environment.

Posted by: razib at September 23, 2003 12:29 PM


This is an important post. One of the main points in the IQ is part genetics theory is the consistency of the Black- White IQ gap (at least in the US) over time. If the Blacks in the UK have now narrowed this gap, then it could challenge this notion.

Some potential ideas I have with regard to this excellent post:

1) In the last study David B cited, the authors reputedly looked at West Indian children aged 7-15yo. Did their IQ's change at all when they reached 18-24yo?

2) What were the ages of the children in the Child Health and Education Study that was cited? Does anyone know if their IQs remained constant by 18-24yo?

3) What (if any) is the average White genetic component to pure West Indians in Britain?

4) How do Black groups fare on standardized tests at late high school or college compared to other groups (Whites, Indians, Chinese...)?

Posted by: R at September 23, 2003 09:36 PM


I am obviously referring to UK Blacks in the fourth point.

Posted by: R at September 23, 2003 09:37 PM


Interesting stuff, Dave. One English study from the seventies found that black West Indian and white English orphans raised in the same institutional environment resulted in the black kids having higher IQs than the white kids, with the b/w mix kids in between. Which would lend support to a black IQ advantage hypothesis.

Posted by: Jason Malloy at September 23, 2003 11:16 PM


Jason: the study you cite is by Tizard (there was a husband-and-wife team of Jack and Barbara Tizard). There is a strong whiff of fish about Tizard's work. I have read somewhere that he was a Communist with a strong ideological commitment to finding the 'correct' answers. I would file his results, along with Skodak and Skeels, Cyril Burt, and a few others, in the drawer marked 'not to be trusted unless independently replicated'.

I will replt to other comments later.

Posted by: David B at September 24, 2003 01:40 AM


But it might be more useful if I reply to them!

Posted by: David B at September 24, 2003 01:47 AM


Immigrants to (say) Britain are generally held to having been self-selected as the most capable, enterprising and so on of a particular ethnic group from a particular country.
This is really no more than a "just so story" - one could equally plausibly say that those Caribbean immigrants who moved to the UK in the 1950s were precisely the least talented, because if they had more brains and ambition, they'd have been able to make it back home in Jamaica or wherever. In fact, I think it's safe to say that the typical Caribbean immigrant of the time tended to come from the lower strata of Caribbean society.

I have read somewhere that he was a Communist with a strong ideological commitment to finding the 'correct' answers. I would file his results, along with Skodak and Skeels, Cyril Burt, and a few others, in the drawer marked 'not to be trusted unless independently replicated'.
But then the same would have to be done with anything by Richard Lynn and Philipe Rushton, wouldn't it? Let's face it, most people who are interested in this subject have some sort of political axe or other to grind. There's no point singling particular researchers out for unusual scrutiny because they're "communists" - all that means is that we don't like the drift of their arguments.

Posted by: Hanno Buddenbrook at September 24, 2003 05:29 AM


Hanno: Tizard produced results that no-one else seems to have produced, and which were very convenient for his particular ideological position. This seems to me to be grounds for caution, if not suspicion. Psychometrics is one of the few scientific fields (other than paleontology!) where the possibility of outright fabrication of data has to be taken seriously. Apart from the cases mentioned, one might add the notorious Bernadine Schmidt case, and Richard Heber, perhaps the only person in the history of the subject to have been literally convicted of fraud! Also, I think Hans Eysenck once said (but I can't find the reference) that an (unnamed) prominent British 'environmentalist' psychologist was suspected of making up his data.

Posted by: David B at September 24, 2003 02:14 PM


Tizard produced results that no-one else seems to have produced, and which were very convenient for his particular ideological position.
While this is certainly good grounds for skepticism, I'll hasten to add that the same is also true of Richard Lynn's work. In particular, his estimates of IQs for African countries are almost totally worthless.

For instance, Lynn's egregious misuse of Raven's matrices scores collected by Ken Owen for black South Africans living in townships, who didn't even share a language in common with their tester, making it extremely doubtful that they actually even understood what the tests required of them, is very much in my mind. Imagine a Tongusk speaker administering a test you'd never seen before in your life to you, and then another Tongusk speaker taking this flawed data and using it to award you an "IQ" of 69!

That is how bad Lynn's work is, but you guys haven't shown any qualms in referring to his "work," if it can be called that. If we're going to subject dubious pro-environment types to extra scrutiny, fair enough, but I say we do the same for the shady characters on the other side of the fence as well.

Posted by: Hanno Buddenbrook at September 24, 2003 03:35 PM


That is how bad Lynn's work is, but you guys haven't shown any qualms in referring to his "work," if it can be called that. If we're going to subject dubious pro-environment types to extra scrutiny, fair enough, but I say we do the same for the shady characters on the other side of the fence as well.

I disagree that Lynn is fringe or "shady". As a counter-point I will note he is one of the seventeen editorial board members for the leading psychometric journal intelligence.

Also Lynn is by no means the only psychologist to administer tests in Africa. There have been over two dozen intelligence studies in Africa. Most of them by different researchers, in different countries, in different regions of the continent. Even Sternberg has done studies there. The results are all pretty consistent with each other, and consistently lower than virtually all other regions of the world tested thus far.

Lynn's African work has been successfully replicated so in that respect he can't be compared to Tizard.

Posted by: Jason Malloy at September 24, 2003 08:42 PM


"That is how bad Lynn's work is, but you guys haven't shown any qualms in referring to his "work," if it can be called that."

I also take issue with this. First of all you need to read Burbridge's Bio:

" I believe that human biodiversity between individuals is more important than between groups, and most differences in behaviour and psychology between groups are probably cultural in origin. But I keep an open mind on the subject."

I haven't yet seen him cite as an authority Lynn, Rushton or any controversial race research, so broad-brushing him for the bio-thought crimes of "you guys" probably isn't too fair. Furthermore, to quote Godless:

"I find Lynn's measurements of African IQs to be suspect. Actually, I take most of his measurements with a massive grain of salt...Another thing that makes me very skeptical of Lynn...he uses extremely crude "geographical averaging" techniques to approximate the IQ of unmeasured nations."

Hmm, that seems to contradict your assertion. But what does Razib have to say about Lynn's work?:

"also, as per the african baseline IQ, i think we need t[o] discard the 60-70 ranges that are coming out of there."

Written, only a few short threads ago. That too appears to be a non-trivial qualm.

I see no justification for your statement. Especially, in the context of using it against Burbridge, who IMHO has demonstrated a lot of intellectual integrity on this blog.

Posted by: Jason Malloy at September 24, 2003 09:30 PM


Jason: thanks for the kind words.

Hanno: I didn't mention Lynn. I wouldn't regard him as a fraud, but I do think he is a flake. I have said in comments on various other people's posts, I don't think IQ comparisons between populations with widely different cultures should be taken very seriously, especially if the differential is less than 1 s.d., as we know that this is well within the range that *can* be due to environmental differences.

My list of 'untrustworthy' researchers included the 'hereditarian' Cyril Burt. I won't go into the thorny question of whether his fraud has been proved beyond a reasonable doubt, but certainly his data cannot be trusted. If fact, I would go further and say that in psychometrics NO SINGLE SOURCE OR TYPE OF DATA SHOULD BE TRUSTED IN ISOLATION.

Returning to the points raised about my post:

PhilT: sure, if you want to study African IQ, go to Africa. But for purposes of educational and social policy in Britain (which was the subject of my post), Africans in Britain are more important than Africans in Africa!

Also, you *can* use data on immigrants to test hypotheses about the population they come from. E.g. if your hypothesis is that IQ of Africans is normally distributed with a mean of 70 and s.d. of 15, then you would only expect about 3% of the population to have IQ above 100, and a tiny proportion above 110. To get an immigrant population with mean of 100, you would need to select from roughly the top 8% of the population of origin. So you could check whether immigration is really hat selective. You could also examine the s.d. and skewness of the immigrant group, which would show whether or not it was the tail-end of a bell curve.

Continued in next comment...

Posted by: David B at September 25, 2003 02:42 AM


Hmm, 'hat selection' - a new principle in evolution!

Returning to comments:

R: I don't know of any studies of immigrant IQ in Britain above the age of 15. It isn't exactly a fashionable research topic. And where would you get your samples? It is virtually impossible to get random samples of adults except in countries with universal military service.

The CHES sample of children were aged 10

I don't know the average 'white' component in West Indian ancestry. Obviously there must be some from slavery days, and Y chromosome analsysis is showing that significant proportions of 'blacks' in Britain have 'European' haplotypes. But a priori one would expect the proportion to be lower than in the US, because the white population in the Caribbean was smaller and slavery ended earlier.

BTW, I skimmed through recent volumes of J. Biosocial Science to see if there was anything relevant more recent than my references. I didn't find anything from the UK, but there is a Dutch study of immigrants to the Netherlands which shows a similar broad picture, i.e. first-generation immigrants with rather low IQ, but improvement as time goes on.

Posted by: David B at September 25, 2003 02:53 AM


Hanno: I think if you read my various posts you will find we are not very far apart on this issue.

PS: I won't be posting or commenting again for at least a few days.

Posted by: David B at September 25, 2003 02:58 AM


I don't know the average 'white' component in West Indian ancestry...But a priori one would expect the proportion to be lower than in the US, because the white population in the Caribbean was smaller and slavery ended earlier.

sounds right-but this is only for the first generation...from what i recall, because of the far smaller number of blacks in england vs. the united states, and their geographical dispersion, they tend to intermarry/intercohabitate at a far greater percentage than american blacks. so the 1st and later 2nd generation "blacks" might be very au lait indeed....

Posted by: razib at September 25, 2003 02:59 AM


I disagree that Lynn is fringe or "shady". As a counter-point I will note he is one of the seventeen editorial board members for the leading psychometric journal intelligence.
Are you trying to say that sitting on the board of "the leading psychometric journal" prevents one from being intellectually dishonest?


There have been over two dozen intelligence studies in Africa. Most of them by different researchers, in different countries, in different regions of the continent. Even Sternberg has done studies there. The results are all pretty consistent with each other, and consistently lower than virtually all other regions of the world tested thus far.
Oh really? Kindly list them, please, and tell me how many of them were conducted in the native languages of the testees. I'd be astonished if even one of these researchers actually understood a single African language other than Afrikaans, which isn't even really African. Where are your references, and are any of them available online to those of us who aren't academics?


so the 1st and later 2nd generation "blacks" might be very au lait indeed....
How do you then explain the educational performance of 1st generation Black Africans, as detailed by David B. in another post? Hardly any of them have the slightest bit of European ancestry, both from what I know from reading books and from what I've seen in my time working in England.

To give one specific example, I know a lot of Ghanaians and Nigerians who went to Cambridge and Oxford, and they were about as black as it is possible to get (well, maybe not as dark as the Sudanese), certainly blacker than the Jamaican immigrants that they are outperforming, even by David B's data.

Posted by: Hanno Buddenbrook at September 25, 2003 12:07 PM


How do you then explain the educational performance of 1st generation Black Africans, as detailed by David B. in another post? Hardly any of them have the slightest bit of European ancestry, both from what I know from reading books and from what I've seen in my time working in England.

why do you insist on pretending as if i believe that the 60-70 mean IQ is valid? in any case, selection bias is obviously important, these people are almost certainly from the fat right tail of the bell curve distributions. the racial mixture comment was not intended to have any psychometric implications any way, just a statement of fact.

you should stop trying to throw up straw men in any case, get's tiresome really quick when we deal with this the 100th time.

Posted by: razib at September 25, 2003 12:40 PM


p.s. also, we shouldn't neglect population substructure within africa-there may be high IQ groups that are sending most of the graduates-though many of these can be explained by cultural factors (the igbo of nigeria for instance tend to be more professional and entrenpenurially accomplished than the yoruba and especially the hausa).

Posted by: razib at September 25, 2003 12:47 PM


why do you insist on pretending as if i believe that the 60-70 mean IQ is valid?
I haven't pretended any such thing - I'm not going to put words in your mouth.

you should stop trying to throw up straw men in any case, get's tiresome really quick when we deal with this the 100th time.
What straw men? You put forward an explanation for the high academic achievement of UK blacks ("1st generation") that I believe is refuted by empirical evidence.

(the igbo of nigeria for instance tend to be more professional and entrenpenurially accomplished than the yoruba and especially the hausa)
This much I'll agree to. I've never met a Hausa foreign student, ever. The split I've seen tends to be 50-50 between the other two you mention though.

Posted by: Hanno Buddenbrook at September 25, 2003 02:47 PM


the igbo of nigeria for instance tend to be more professional and entrenpenurially accomplished than the yoruba
The Igbo are more entrepreneurial, but the Yoruba are more professional (doctors etc). Hausa dominate the military.

why do you insist on pretending as if i believe that the 60-70 mean IQ is valid?
I haven't pretended any such thing - I'm not going to put words in your mouth.

No point arguing with an ideologue.

Posted by: fredrik at September 25, 2003 04:09 PM


THE DUTCH STUDY
David, can you give me the citation for the Dutch study on immigrants. I would like to take a look at it.

Posted by: Esther at September 26, 2003 02:58 AM


Esther: I will have to look up the Dutch reference the next time I go to the library - I didn't take a note. When I get the ref I will post it on the main board.

My comment about the proportion of 'white' ancestry in West Indians was in reply to a question specifically about 'pure' West Indians, which I took to mean West Indians in the WI or first-generation migrants. Obviously the level of intermarriage (or at any rate interbreeding!) between West Indians and Whites in Britain is very high, but the offspring would usually be regarded as 'mixed' rather than 'black Caribbean'. We don't follow the curious American custom of describing anyone with mixed ancestry as 'black'.

Posted by: David B at September 28, 2003 07:06 AM