Intelligence was assessed using the Standard Progressive Matrices in 316 MZ and 550 same-sex DZ twins with a mean age of 10 years in Sudan. Heritability was estimated at 0.172 and shared environmental influences at 0.596.

Two administrations of the Coloured Progressive Matrices in Egypt were compared. The first was administered to a large, representative national sample between 2011 and 2013. The second was administered to primary school pupils in villages in Menoufia in northern Egypt in 2017. Adjusting for the Flynn Effect, the IQ of the rural northern Egyptians was shown to be statistically significantly higher than the national average. It is demonstrated that this is consistent with regional socioeconomic differences in Egypt, which strongly imply that northern Egypt has a higher average IQ than southern Egypt.

This study was based on data for a sample of 1756 Egyptian primary school children (863 boys and 893 girls) aged 5–11 years assessed for intelligence with Raven’s Coloured Progressive Matrices (CPM). The results showed that boys obtained a slightly higher IQ than girls and had greater variance.

This study was based on two independent studies which in total consisted of 1812 school pupils aged 6–12 years in Saudi Arabia. Study I consisted of 1591 school pupils (609 boys and 982 girls) attending state schools, and Study II consisted of 211 boys with learning disabilities. Intelligence (measured using the Standard Progressive Matrices Plus for Study I and the Standard Progressive Matrices for Study II), head size and height were measured for the two samples. The results showed that intelligence was statistically significantly correlated with head circumference (r=0.350, p<0.001 for Study I and r=0.168, p<0.05 for Study II) and height (r=0.271, p<0.001 for Study I and r=0.178, p<0.05 for Study II).