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[ODP] A Study of the IQ in Sudan
Richard is too old to use the forum properly. He sent this to my email. I submit it here on his behalf.


Salaheldin Farah Attallah Bakhiet, Richard Lynn

The Coloured Progressive Matrices (CPM) was standardized in Sudan in
2004 on a sample of 1683 6-9 year olds. The sample obtained a British IQ of 77.

Key words:
Sudan, Coloured Progressive Matrices, intelligence

The submission has been moved to Google Drive.
I have recreated the dataset here:

Neither the weighted average, unweighted average or median is the same as that the mean the authors report. What method did they use to calculate it? Probably the weighted average is the best. This will boost the result a bit upwards.

The extremely high negative correlation between age and centile deserves discussion. It seems in line both with an environmental depression hypothesis (cumulative deficit, cf. Jensen 1977) and a developmental hypothesis where the growth of general intelligence is slower in Sudan which would result in an decreasingly lower centile compared with British norms.

One could do a linear regression on the relationship to try and predict the adult centile on British norms, though this probably would give a very low estimate of g.

As for formatting, the paper needs some revision. There needs to be a mention of the journal, when it was submitted, and when it will be published (when accepted).

Finally, I would like the authors to upload a scan of the original study in Arabic so that anyone else who speaks the language can check the veracity of the data.

Jensen, A. R. (1977). Cumulative deficit in IQ of blacks in the rural South. Developmental Psychology, 13, 1841—1891. Reprinted in: Willerman, L., and Turner, R. G. (Eds.), Readings about individual and group differences. San Francisco: W. H. Freeman, 1979. Pp. 83—91.
If my memory is correct, Jensen (1977) article was a sibling study (IQolder-IQyounger) but that's not what I see from the submitted paper here. Or did i miss something ?
I didn't mean the designs were similar, just that more information about the idea can be found there.
There is no information on the participants of this study in terms of social class or ethnic background. We are simply told that they are from Khartoum state. Because the capital is located there, the population of Khartoum state is very diverse. In particular, there are around two million displaced persons from the south and the west:

"The population of metropolitan Khartoum (including Khartoum, Omdurman, and Khartoum North) is growing rapidly and ranges from six to seven million, including around two million displaced persons from the southern war zone as well as western and eastern drought-affected areas." (Wikipedia - Demographics of Sudan)

Unless we can find out more about the characteristics of the study population, I don't see how we can draw any meaningful conclusions from the study's findings.
Dear Emil

A Study of the IQ in Sudan

We have revised the paper to meet the reviewers’ comments and attach the revision.


There are two changes in the new version :

The mean of the British percentiles is 18 and is equivalent to a British IQ of 86.25.

This IQ needs adjustment for the increase of the British IQ over the 22 years from 1982 to 2004 which is calculated by Flynn (2012) as 3.8 IQ points a decade and was therefore 8.36 IQ points over the 22 years. This reduces the Sudan IQ from 86.25 to 77.9 and can be rounded up to 78. It will be noted that the British percentiles of the Sudanese children declined with age. The 6 year olds scored at the 25th British percentile while the 9 year olds scored at the 9.75th British percentile. This decline is consistent with Jensen’s (1977) cumulative deficit hypothesis stating that an adverse environmental has a depression effect on intelligence that increases with age that he demonstrated for blacks in the rural south of the United States.

They, however, did not answer the questions raised by Frost. If there is no such information on social and ethnic background, the authors should probably mention it.

I will send an email to the authors.
Here is another revision from Lynn.
Nice, so they have included the following

Khatib, Mutwakkil and Hussain’s study (2006) was a standardisation of the Raven’s Coloured Progressive Matrices (CPM) (Raven, Court & Raven, 1995) in Khartoum State, Sudan, in 2004 on a sample of 1683 participants consisting of males (728) and females (955). There was no information on the participants of this study in terms of social class or ethnic background.

The data are shown in the table. The right hand column gives the British percentiles on the 1982 British standardisation given by Raven, Court & Raven (1995).

I was the one who has suggested this to them. But it's ok. The problem now is the table. It is still cut in half, not centered in the main text. I don't see the left portion of the table. Is it also what you have ?
Yes. However, the table is fixable by the editor (i.e. me) without author input (simply open the table settings and set the alignment to center). Richard is over 80 years old, so his use of computers is less than perfect. We will have to try to help him.

The formatting of the file was decidedly strange. I have cleaned it up. I have removed the repeated sentence on page 1. I have added "unweighted" before the mean to clarify which mean was used. I have fixed the table as well.

The paper now looks fine.

I don't have any other comments other than the authors should supply a scan of the original Arabic paper so that others who can read Arabic can study it.
Thanks. The table looks very good now. I have emailed the authors and asked if they can supply a scan as a supplementary file.
The authors sent me the scan. It is attached.
"There was no information on the participants of this study in terms of social class or ethnic background"

I would add:

"This may be a problem because of the social and ethnic heterogeneity of Khartoum state, particularly the large number of in-migrants, including refugees, from all parts of the country."
Maybe we can find someone who can read the original and verify the information.
Maybe we can find someone who can read the original and verify the information.

I don't find it reasonable. Trying to find people who can read arab is no easy task, and get them ready to translate the text is even harder, as there is no reason why they would accept. No one here can read the original document. If the condition for publication is the translation of the document, I'm afraid you're making the article impossible to be published. I don't think Lynn can read it, and the numbers he has reported probably come directly from Bakhiet, who should be able to read these documents. At best, Bakhiet should confirm directly, here or by email, that the numbers are correct. I don't think we should ask more than this.

Personally, I can approve the publication of the article already. Of course, it's unfortunate we don't have information about ethnicity. But if the data is representative of the population, I don't see where the problem is.
If the authors note that the sample has unknown representativeness and that the curious reader may consult the original Arabic (if he can), then I will approve.
Meng Hu,

it is very doubtful that the sample was representative of the population of Khartoum state, since that state is ethnically heterogeneous with large numbers of migrants from the north, south, and west of Sudan. In any case, the phrase "representative of the population" has no useful meaning in this context. Most people from outside Sudan, including probably the author, assume that words like "Sudanese" or "Khartoumian" correspond to some kind of objective cultural or ethnic reality. They don't.

Let's suppose that someone tested the IQ of a hundred people in London, Paris, or Los Angeles. Would you publish that study even if it had no information at all about the participants' ethnicity?
The thing about London is that the different groups living there vary quite a bit in their mean g, but the different groups in Africa are generally thought to be quite similar in g. If so, then it is not so important which groups one sample there while it is important in London or similar.
"the different groups in Africa are generally thought to be quite similar in g."

I humbly disagree. The word 'Africa' is a geographical term that means nothing culturally or ethnically. There are at least four major culture areas within Africa: North Africa (which has more in common with the Middle East), the Horn of Africa (also influenced by the Middle East), sub-Saharan Africa, and the formerly Khoisan areas of southern Africa.

At the time of this IQ study, Sudan's territory extended into three of the above culture areas. This is why South Sudan recently seceded. It had very little in common with the rest of the country.
I meant in Sub-Saharan Africa. NA is known to be somewhat smarter (in the 85 area).

But what exactly would you want the authors to do? Information is usually scant in the studies of developing nations. The solution is to be cautious in interpreting the data, not to ignore the data entirely.