Hello folks, I would like to welcome a new author to the site, Afrosapiens, formerly the commenter Anti-Hereditarian. I am very proud to have him on here. It is true that he is anti-HBD, but I think I ought to provide both viewpoints here as this is not a settled question at all in science as there is no consensus one way or the other. Really most anyone on the Left can write here, but most Lefties don’t because they consider the site toxic.
As a freshly disembarked anti-racist commenter (and now author) taking part in conversations about West Africa and her diaspora, I thought it would be interesting that we discuss the figures at the heart of the controversy: West Africa’s average IQ scores.
For us to have an objective debate, I decided to use Wicherts et al.’s literature review of studies reporting African cognitive testing scores.
All existing studies
Number of studies : 14
Countries : Ghana, Guinea, Nigeria, Senegal, Sierra Leone
Number of test-takers : 5226
Average year of the studies : 1970 (unweighted average : 1973)
Average measured IQ : 83.5 (unweighted average : 84.1)
Average actualized IQ (UK norms + Flynn effect) : 78.2 (unweighted average : 79.8)
As a whole, 14 studies involving cognitive testing have been performed on West African subjects and included a total of 5,226 persons from Ghana, Guinea, Nigeria, Senegal and Sierra Leone, 5 countries which are home to around two-thirds of West Africa’s population. The oldest of these studies dates to 1935, whereas the most recent was published in 2002. The average year of reporting was 1970 if we account for the size of the samples or 1973 unweighted.
As measured by the studies’ authors, the West African subjects had an average IQ of 83.5 or 84.1 if each study is given the same weight. When corrected for the Flynn Effect and adapted to British norms for international comparison, the scores were lowered to 78.2 or 79.8 if unweighted.
In my opinion though, correcting for the Flynn effect in an attempt to present studies dating to 1970 on average as chronologically representative of today’s mean cognitive performance of a population appears fallacious. Instead of applying a quite arbitrary corrective in order to give a current day meaning to multiple decades-old studies, I would simply conclude that studies performed since 1935 have have found an average IQ of 83.5 in 5226 West African test-takers.
Since most of these studies were realized for medical or educational purposes, only a few included subjects who were mostly healthy representatives of their respective country’s population. To make national or regional IQ estimates, the interested scholars had to make their own selections using different methods that later came to be criticized and debated. In the following, I will show and discuss the results from studies selected by Lynn & Vanhanen and Wicherts et al. who are the main partakers in the academic dispute.
Studies selected by Lynn & Vanhanen
Number of studies: 2
Countries: Ghana, Guinea
Number of test-takers: 275
Average year of the studies: 1973 (unweighted average:1958)
Average measured IQ: 78.7 (unweighted average: 72.5)
Average actualized IQ (UK norms + Flynn effect): 73.4 (unweighted : 69.35)
Average actualized IQ Lynn and Vanhanen : 76.9 (unweighted : 71.5)
Only two studies met Lynn & Vanhanen’s undisclosed selection criteria. Later research has suggested that the highest predictor of inclusion in Lynn & Vanhanen’s review was a lower IQ score.
The first study dates from 1935 and samples 50 unschooled children from Guinea who are probably dead or very old today. These children were found to have a 63 mean IQ . The second sample is from Ghana and was reported in a 1981 study as composed of 225 representative adults from Accra, Ghana who scored 82. Lynn & Vanhanen’s averaging methodology does not take the samples’ sizes into account and delivers unweighted results, on this basis the regional IQ of West Africa is 71.5.
Studies selected in Wicherts et al.
Number of studies: 4
Countries: Ghana, Nigeria, Senegal, Sierra Leone
Number of test-takers: 1,379
Average year of the studies: 1969 (unweighted average: 1972)
Average measured IQ: 83.7 (unweighted average: 85.5)
Average actualized IQ (UK norms + Flynn effect): 76.3 (unweighted average: 79.1)
Using rigorous systematic selection methods described here, Wicherts et al. used 4 studies totaling 1,379 West African subjects from Ghana, Nigeria, Senegal and Sierra Leone. 559 Senegalese school children were tested with a 77.9 average IQ in 1960; a mix 393 upper-class and lower-class Nigerian children scored 87.2 in 1972; 202 Sierra Leonese children in an experimental school had a 94.8 mean IQ in 1973; the 225 representative adults from Accra used in Lynn & Vanhanen were considered by Wicherts et al., their mean measured IQ in 1981 was 82.
Following Wicherts et al’s method of correcting for the Flynn effect, translating to UK norms and weighting the average, West Africa’s mean IQ was 76.3.
To summarize :
Weighted average measured IQ: all studies, 83.5 ; Lynn & Vanhanen 78.7; Wicherts et al. 83.7
Unweighted average measured IQ : all studies, 84.1; Lynn & Vanhanen 72.5; Wicherts et al. 85.5
Weighted average actualized IQ : all studies, 76.2; Lynn & Vanhanen 76,9; Wicherts et al. 76.3
Unweighted average actualized IQ : all studies, 78.8 ; Lynn & Vanhanen 71.5; Wicherts et al. 79.1
In my opinion, the most meaningful figure is the weighted measured average of the studies selected according to the rigorous systematic methodology of Wicherts et al. thus giving a mean IQ of 83.7 IQ for the 1,379 West Africans tested between 1960 and 1981. As I said at the beginning of the post, I protest actualization. The numbers that must be considered are those that were found relevant in the context of the study: the numbers were measured and used for a practical purpose. Giving a 2015 value to a 1935 study makes no sense at all in my opinion.
However, Lynn & Vanhanen would most likely have based their regional estimate on the unweighted average of the two samples from 1935 and 1981 totaling 275 subjects. With this method, West Africa is found with a 71.5 IQ though the test-takers were measured with a weighted average IQ of 78.7.
Using Lynn & Vanhanen’s national IQ predictions based on international standardized tests of scholastic achievement, scores from Nigeria predicted a national IQ of 89.5 in 2006 and 87.1 in 2007 (average 88.3) while scores from Ghana gave a predicted IQ of 68.8 in 2003 and 71.8 in 2007 (average 70.3). Based on these figures, the West African Average was 79.3 between 2003 and 2007. However, if we give importance to the fact that Nigeria’s total population in 2015 is 182 million, while Ghana’s is only 27 million, the weighted average predicted IQ is 86 for West Africa.
In order to remain partial with respect to the inclusion rules used by by both sides of the controversy, I chose to make my estimate with the weighted average measured IQ’s in the studies used by Lynn & Vanhanen and Wicherts & al in addition to the IQ’s predicted from scholastic achievement tests.With this methodology, the estimated mean IQ of West Africa has been 82.8 since the beginning of cognitive testing in this region.
Wicherts et al. however would have taken weighted averages corrected for the Flynn effect and changed to UK norms plus the unweighted average of Ghana and Nigeria’s performances on scholastic achievement tests resulting in a 77.8 IQ estimate for West Africa.
For you to make your own judgment on whose estimate is the most biased, take a look at the differentials shown under.
Afrosapiens : 82,8 (difference with Wicherts et al : +5 ; difference with Lynn & Vanhanen : +11,3)
Wicherts et al : 77,8 (difference with Afrosapiens : -5 ; difference with Lynn & Vanhanen : +6,3)
Lynn & Vanhanen : 71,5 (difference with Afrosapiens : -11,3 ; difference with Wicherts et al : -6,3)
See original the data here
To have a better understanding of the different IQ estimates and their actual meaning, my upcoming post will examine the interactions between crystallized intelligence, fluid intelligence and the concept of heritability. But first, let’s talk about the numbers.