In 2002 Richard Lynn and Tatu Vanhanen’s book IQ and Wealth of Nations estimated the IQs of 185 countries. Critics accused them of cherry picking sources, using unrepresentative samples, comparing and combining samples tested on wildly different tests taken decades apart, and daring to think IQ could be measured cross-culturally. And yet despite nearly two decades of opprobrium, those national IQs remain a landmark, cited in countless peer reviewed articles and repeatedly revised.

One way Lynn has validated his numbers is by showing their high correlation with international exams like Programme for International Student Assessment (PISA). Another independent data-set against which Lynn’s numbers can be tested (assuming he already hasn’t done so) is the IEA‘s Trends in International Mathematics and Science Study (TIMSS). Ostensibly an achievement test, the math section resembles an IQ test, and the test is scored so that most countries average between 400 and 600.

Sample items:

Using the score distribution of UK students as a reference group (see technical note below), I converted the scores from 39 countries to IQ equivalents. My source for the TIMMS scores is exhibit 1.2 in this report.

Country	TIMMS score (8th grade math; 2015)	IQ equivalent
Singapore	621	118
Korea, Rep. of,	606	116
Chinese Taipei	599	114
Hong Kong SAR	594	113
Japan	586	112
Russian Federation	538	103
Kazakhstan	528	102
Canada	527	101
Ireland	523	101
United States	518	100
England	518	100
Slovenia	516	99
Hungary	514	99
Norway	512	99
Lithuania	511	98
Israel	511	98
Australia	505	97
Sweden	501	97
Italy	494	95
Malta	494	95
New Zealand	493	95
Malaysia	465	90
United Arab Emirates	465	90
Turkey	458	89
Bahrain	454	88
Georgia	453	88
Lebanon	442	86
Qatar	437	85
Iran, Islamic Rep. of	436	85
Thailand	431	84
Chile	427	83
Oman	403	79
Kuwait	392	77
Egypt	392	77
Botswana	391	77
Jordan	386	76
Morocco	384	76
South Africa	372	73
Saudi Arabia	368	73

Consistent with Lynn’s hierarchy, we find that East Asian countries cluster around the top (Japan IQ 112 to Korea, Repub of, IQ 116), followed by white majority countries (New Zealand IQ 95 to Russian federation IQ 103), followed by Dark Caucasoid countries (Saudi Arabia IQ 73 to United Arab Emirates IQ 90) and lastly sub-Saharan countries (South Africa IQ 73 to Botswana IQ 77). And while Lynn’s data was ridiculed for declaring entire countries “mentally retarded”, it’s perhaps a sign of higher quality data that no country in this data-set averaged below IQ 70 (though most of the poorest countries chose not to participate).

Technical note

On page 95 of the report, we’re told that only 10% of England’s 8th graders could score 625+, 36% could score 550+, 69% could score 475+, and 93% could score 400+. Subtracting these percentages from 100 gives the following percentiles: 90, 64, 31, and 7 which can be converted to the following IQs: 119, 105, 93, and 78. Now that we have the IQ equivalents of four TIMMS scores, we can make a linear equation converting TIMMS to IQ which is IQ = 0.18(TIMMS score) + 6.5: