Nations and intelligence
|Abilities, traits and constructs|
|Models and theories|
|Fields of study|
The relationship between nations and IQ is a controversial area of study.
Richard Lynn and Tatu Vanhanen have constructed IQ estimates for many countries using literature reviews, international student assessment studies and other methodologies to create estimates. These national estimates have been criticized on theoretical and methodological grounds.
Lynn and Vanhanen estimates 
Lynn and Vanhanen have conducted a number of studies which have been highly criticized both on theoretical and methodological grounds.
"Average IQ values in various European countries" 
The 1981 article "Average IQ values in various European countries" by V. Buj is the only international IQ study that over a short time period has compared IQs using the same IQ test. It was probably done in the 1970s in the capital cities or in the biggest town in 21 European countries and Ghana. Rindermann (2007) states that it is of dubious quality with scant information regarding how it was done. The correlations with the other measures of national intelligence, except the PISA student assessment study, are good.
"IQ and the Wealth of Nations" 
The 2002 book IQ and the Wealth of Nations by Richard Lynn and Tatu Vanhanen listed average national IQ for the nations of the world. A literature review listed IQ tests from 81 nations. In 104 of the world's nations there were no IQ studies and IQ was estimated based on IQ in surrounding nations. Scores were adjusted for several factors such as the Flynn effect. Susan Barnett and Wendy Williams wrote that "we see an edifice built on layer upon layer of arbitrary assumptions and selective data manipulation. The data on which the entire book is based are of questionable validity and are used in ways that cannot be justified." They also wrote that cross country comparisons are "virtually meaningless."
"IQ and Global Inequality" 
The 2006 book IQ and Global Inequality by Lynn and Vanhanen revised the scores from the previous book. A new literature review listed IQ tests from 113 nations. The methods of the study were criticized by Richard E. Nisbett for relying on small and haphazard samples and for ignoring data that did not support the conclusions.
"A systematic literature review of the average IQ of sub-Saharan Africans" 
The 2009 article "A systematic literature review of the average IQ of sub-Saharan Africans" by Jelte M. Wicherts, Conor V. Dolana, and Han L.J. van der Maas in a critique of "IQ and Global Inequality" reviewed the literature on IQ tests in sub-Saharan Africa. Including a number of studies excluded in "IQ and Global Inequality" it found a higher average IQ of 82 for sub-Saharan Africa.
"National IQs updated for 41 Nations" 
The 2010 article "National IQs updated for 41 Nations" by Lynn revised "IQ and Global Inequality" and presented new calculated national IQs for 25 countries which had previously only been estimated from neighboring nations IQs and revised national IQs for 16 countries.
International student assessment studies 
There are a number of international student assessment studies:
- International Association for the Evaluation of Educational Achievement-Reading-Study (1991)
- Trends in International Mathematics and Science Study (TIMSS) (1994–1995, 1999, 2003)
- Programme for International Student Assessment (PISA) (2000–2002, 2003, and 2006)
- Progress in International Reading Literacy Study (PIRL) (2001)
Rindermann (2007) states that the correlations between international student assessment studies and measures of national IQ are very high. Using the same statistical method used to measure the general intelligence factor (g) he finds evidence for that the "student achievement assessments and intelligence tests primarily measure a common cognitive ability". The international student assessment studies have the advantages of standardized testing over a short time period. The IQ-data collections have the advantage of including older people and more developing nations. Lynn and Mikk (2009) similarly find a high predictive ability and correlation between the latest PISA 2006 and the national IQs from the two books.
The Flynn effect 
In the 20th century there has been a worldwide continual increases in measured IQ. This rise has been correlated with degrees of rising education levels, and as such may provide a partial explanation for observed differences in average IQ scores between nations. One recent study suggests that the Flynn effect has ended in some developed nations such as Denmark and Norway, and suggests that this is due to immigration from countries with lower education levels or due to changes in education policies within the countries.
Limitations and criticisms of the data sets 
Limitations and criticisms of the IQ-data collections 
Rindermann (2007) writes that the mixture of many different tests and the not always clear representativeness of the samples seem to be the most serious problems. Furthermore, the measurement years vary, which is problematic because of the Flynn effect. Using the same adjustment for all nations is likely sometimes incorrect because since the 1970s developing nations have seen higher increases than the developed world. The method of averaging neighboring countries for an estimation for the many nations that did not have measured IQs, while having a high correlation (0.92) with the measured results in the case of the 32 nations that changed from the estimated to the measured categories between the two books, is likely problematic since some research indicates that absence of IQ tests indicates conditions such as poverty or war that may affect IQs. "In addition, some errors in the data have been observed".
As noted above, the article "A systematic literature review of the average IQ of sub-Saharan Africans" (2009) argued that a number of studies showing higher IQ values for sub-Saharan Africa had been excluded by "IQ and Global Inequality". Regarding four studies comparing and finding agreement between Lynn's estimated national IQs and the student assessment tests, they disagree regarding sub-Saharan Africa but write "these four studies appear to validate national IQs in other parts of the world." Richard Lynn and Gerhard Meisenberg (2009) replied that "critical evaluation of the studies presented by WDM shows that many of these are based on unrepresentative elite samples" and that a further literature review, including taking into account results in mathematics, science, and reading, gave "an IQ of 68 as the best reading of the IQ in sub-Saharan Africa". Wicherts and colleagues (2010) in another reply made several examinations of unrepresentativeness and stated: "In light of all the available IQ data of over 37,000 African testtakers, only the use of unsystematic methods to exclude the vast majority of data could result in a mean IQ close to 70. On the basis of sound methods, the average IQ remains close to 80." Consequently some later studies using IQ data have checked their results against data from both sources.
Limitations and criticisms of the international student assessment studies 
Rindermann (2007) writes that data from many developing nations are missing which is the case for more nations than for IQ data. The Flynn effect has to be adjusted for. In some nations school attendance is low. Even for the same test national organizers sometimes differ in implementation and exclusion rates differ.
Causes of the national differences 
A large number of factors are known to affect measured IQ temporarily or permanently. The factors responsible for the Flynn effect may be partly or completely behind national IQ differences. See Flynn effect#Proposed explanations. Examples being that the developing world is afflicted to a greater degree than the developed world by poor nutrition (deficiency in energy, protein, and micronutrients) and infectious diseases. See also Health and intelligence.
Controversially, the two books argued for a large genetic explanation. Such a role of genetics may or may not be related to race which is itself a controversial topic. Lynn argued further for this in the books Race Differences in Intelligence: An Evolutionary Analysis (2006) and The Global Bell Curve: Race, IQ, and Inequality Worldwide (2008).
Kanazawa (2008) also argues for a genetic role. He writes that cold climate and harsh winters (the study uses mean annual temperature) as well as environment novelty (the study uses three different measure of distance from the ancestral environment in sub-Saharan Africa: ordinary distance and differences in latitudes and longitudes) have been proposed as important factors behind the genetic evolution of human intelligence. The study found independent support for both theories and argues that they together explain half to two-thirds of variance in national IQ.
In contrast, Wicherts, Borsbooma, and Dolana (2010) criticized this and some other evolutionary studies for problems such as ignoring or assuming that the Flynn effect is equal worldwide and assuming that there have been no migrations and changes in climate over the course of evolution. "In addition, we show that national IQs are strongly confounded with the current developmental status of countries. National IQs correlate with all the variables that have been suggested to have caused the Flynn Effect in the developed world."
Eppig, Fincher, and Thornhill (2010) states that distance from Africa, temperature, and most importantly by a large margin, prevalence of infectious disease predict national IQs. Education, literacy, GDP, and nutrition were not important as independent factors (however, the prevalence of infectious diseases is likely greatly affected by these factors). The authors argue that "From an energetics standpoint, a developing human will have difficulty building a brain and fighting off infectious diseases at the same time, as both are very metabolically costly tasks" and that "the Flynn effect may be caused in part by the decrease in the intensity of infectious diseases as nations develop."
Associated factors 
|This section about associated factors relies on references to primary sources. (February 2012)|
"IQ and Global Inequality" found correlations between a number of factors and IQ including GDP per capita, literacy, life expectancy, inequality, lower abject poverty, undernourishment, maternal mortality, and infant mortality.
A number of studies using the IQ scores from the books have found that higher average national IQ is associated with various measures of higher economic growth and economic development. At least one study did not find this association.
Jones and Schneider (2010) write that a country’s average IQ score is a useful predictor of the wages that immigrants from that country earn in the U.S., whether or not one adjusts for immigrant education.
In a study by Rindermann and Meisenberg (2009), lower national IQs associated with higher HIV-infection rates, which is stronger effect than the association with low gross domestic product and low modernization.
Reeve (2009) writes that higher IQ, independent of national wealth, is associated with lower fertility rates, lower infant mortality rate, lower maternal mortality rate, fewer deaths due to HIV/AIDS, and longer life expectancy.
Both higher GDP and IQ independently reduce fertility according to a study by Meisenberg (2009) that argues that "at present rates of fertility and mortality and in the absence of changes within countries, the average IQ of the young world population would decline by 1.34 points per decade and the average per capita income would decline by 0.79% per year."
"Smart fraction" 
Some studies have found that the "smart fraction" (the most intelligent part of the population) is particularly important. Weiss (2009) found that growth of GDP per capita could be derived as a linear function of the percentage of the population with an IQ above 105. Rindermann et al. (2009) found that the cognitive ability of the 5% of the population who scored the highest was more important than average national IQ scores for GDP, patent rates, Nobel Prizes, number of scientists, government effectiveness, democracy, rule of law, and political liberty. For HIV, AIDS, and homicide the cognitive ability of the 5% of the population who scored the lowest was most important.
- Rindermann,H. (2007). The g-factor of international cognitive ability comparisons: The homogeneity of results in PISA, TIMSS, PIRLS and IQ-tests across nations. European Journal of Personality, 21, 6 67−706 http://onlinelibrary.wiley.com/doi/10.1002/per.634/abstract
- Buj, V. (1981). Average IQ values in various European countries. Personality and Individual Differences, 2, 168–169
- Barnett, Susan M. and Williams, Wendy (August 2004). "National Intelligence and the Emperor's New Clothes". Contemporary Psychology: APA Review of Books 49 (4): 389–396.
- Nisbett, Richard. 2009. Intelligence and how to get it. pp. 215.
- Jelte M. Wicherts, Conor V. Dolana, and Han L.J. van der Maas, A systematic literature review of the average IQ of Sub-Saharan Africans, Intelligence, Volume 38, Issue 1, January–February 2010, Pages 1-20, http://dx.doi.org/10.1016/j.intell.2009.05.002
- Mankind Quarterly, Vol. 50, No. 4 (Summer 2010) pp. 275-296, "National IQs updated for 41 Nations", Richard Lynn. http://www.mankindquarterly.org/summer2010_lynn.html
- National IQs predict educational attainment in math, reading and science across 56 nations, Richard Lynna and Jaan Mikk, Intelligence, Volume 37, Issue 3, May–June 2009, Pages 305-310
- Teasdale TW, Owen DR (2008). "Secular declines in cognitive test scores: A reversal of the Flynn Effect" (PDF). Intelligence 36 (2): 121–6. doi:10.1016/j.intell.2007.01.007.
- "The average IQ of sub-Saharan Africans: Comments on Wicherts, Dolan, and van der Maas", Richard Lynna and Gerhard Meisenberg, Intelligence, Volume 38, Issue 1, January–February 2010, Pages 21-29 http://dx.doi.org/10.1016/j.intell.2009.09.009
- The dangers of unsystematic selection methods and the representativeness of 46 samples of African test-takers, Jelte M. Wicherts, Conor V. Dolana and Han L.J. van der Maas, Intelligence Volume 38, Issue 1, January–February 2010, Pages 30-37
- Christopher Eppig, Corey L. Fincher, and Randy Thornhill, Parasite prevalence and the worldwide distribution of cognitive ability Proc R Soc B 2010: rspb.2010.0973v1-rspb20100973. http://rspb.royalsocietypublishing.org/content/early/2010/06/29/rspb.2010.0973.abstract
- IQ in the Utility Function: Cognitive skills, time preference, and cross-country differences in savings rates, Garett Jones and Marta Podemska, (Presented at Canadian Economics Association meetings, June 2010) http://mason.gmu.edu/~gjonesb/
- Case for Non-Biased Intelligence Testing Against Black Africans Has Not Been Made: A Comment on Rushton, Skuy, and Bons (2004) 1*, Leah K. Hamilton1, Betty R. Onyura1 and Andrew S. Winston International Journal of Selection and Assessment Volume 14 Issue 3 Page 278 - September 2006
- Culture-Fair Cognitive Ability Assessment Steven P. Verney Assessment, Vol. 12, No. 3, 303-319 (2005)
- The attack of the psychometricians. DENNY BORSBOOM. PSYCHOMETRIKA VOL 71, NO 3, 425–440. SEPTEMBER 2006.
- Intelligence: Knowns and Unknowns, Ulric Neisser et al, American Psychologist, Vol. 51, No. 2. (February 1996), pp. 77-101.
- Temperature and evolutionary novelty as forces behind the evolution of general intelligence, Satoshi Kanazawa, Intelligence, Volume 36, Issue 2, March–April 2008, Pages 99-108 http://dx.doi.org/10.1016/j.intell.2007.04.001
- Why national IQs do not support evolutionary theories of intelligence, Jelte M. Wicherts, Denny Borsbooma and Conor V. Dolana, Personality and Individual Differences, Volume 48, Issue 2, January 2010, Pages 91-96, http://dx.doi.org/10.1016/j.paid.2009.05.028
- Christopher Eppig, Corey L. Fincher, and Randy Thornhill Parasite prevalence and the worldwide distribution of cognitive ability Proc R Soc B 2010: rspb.2010.0973v1-rspb20100973. http://rspb.royalsocietypublishing.org/content/early/2010/06/29/rspb.2010.0973.abstract
- Dickerson, R. E. (May–June 2006). "Exponential correlation of IQ and the wealth of nations". Intelligence 34 (3): 291–295. doi:10.1016/j.intell.2005.09.006.
- Intelligence, Human Capital, and Economic Growth: A Bayesian Averaging of Classical Estimates (BACE) Approach, Garett Jones and W. Joel Schneider, JOURNAL OF ECONOMIC GROWTH, Volume 11, Number 1, 71-93, doi:10.1007/s10887-006-7407-2
- Relevance of education and intelligence at the national level for the economic welfare of people, Intelligence, Heiner Rindermann, Volume 36, Issue 2, March–April 2008, Pages 127-142
- Rati Ram. (2007). "IQ and economic growth: Further augmentation of Mankiw-Romer-Weil model". Economics Letters, Volume 94, Issue 1, January 2007, Pages 7-11 http://dx.doi.org/10.1016/j.econlet.2006.05.005
- The Impact of Intelligence and Institutional Improvements on Economic Growth, Erich Weede, Sebastian Kämpf, Kyklos, Volume 55, Issue 3, pages 361–380, August 2002
- Does Human Capital Strongly Affect Economic Growth Rates? Yes, But Only If Assessed Properly, Erich Weede, Comparative Sociology, Volume 3, Number 2, 2004 , pp. 115-134(20) http://www.ingentaconnect.com/content/brill/comps/2004/00000003/00000002/art00002
- IQ and the Wealth of Nations. A Critique of Richard Lynn and Tatu Vanhanen's Recent Book, 2003, Thomas Volken, European Sociological Review Volume. 19, Issue 4, Pp. 411-412 http://esr.oxfordjournals.org/content/19/4/411.abstract
- IQ inf the Production Function: Evidence from Immigrant Earnings, Garett Jones, W. Joel Schneider, Economic Inquiry, Volume 48, Issue 3, pages 743–755, July 2010 http://onlinelibrary.wiley.com/doi/10.1111/j.1465-7295.2008.00206.x/full
- Relevance of education and intelligence for the political development of nations: Democracy, rule of law and political liberty, Heiner Rindermann, Intelligence, Volume 36, Issue 4, July–August 2008, Pages 306-322, http://dx.doi.org/10.1016/j.intell.2007.09.003
- MARTIN VORACEK (2008) CROSS-NATIONAL SOCIAL ECOLOGY OF INTELLIGENCE AND SUICIDE PREVALENCE: INTEGRATION, REFINEMENT, AND UPDATE OF STUDIES. Perceptual and Motor Skills: Volume 106, Issue , pp. 550-556. http://www.amsciepub.com/doi/abs/10.2466/pms.106.2.550-556
- National differences in intelligence, crime, income, and skin color, J. Philippe Rushton and Donald I. Templer, Intelligence, Volume 37, Issue 4, July–August 2009, Pages 341-346, http://dx.doi.org/10.1016/j.intell.2009.04.003
- Average intelligence predicts atheism rates across 137 nations, Richard Lynn, John Harvey, and Helmuth Nyborg, Intelligence, Volume 37, Issue 1, January–February 2009, Pages 11-15, http://dx.doi.org/10.1016/j.intell.2008.03.004
- IQ, cultural values, and the technological achievement of nations, Garry A. Gelade, Intelligence, Volume 36, Issue 6, November–December 2008, Pages 711-718, http://dx.doi.org/10.1016/j.intell.2008.04.003
- Relevance of education and intelligence at the national level for health: The case of HIV and AIDS, Heiner Rindermann and Gerhard Meisenberg, Intelligence, Volume 37, Issue 4, July–August 2009, Pages 383-395, http://dx.doi.org/10.1016/j.intell.2009.03.005
- Expanding the g-nexus: Further evidence regarding the relations among national IQ, religiosity and national health outcome, Charlie L. Reeve, Intelligence, Volume 37, Issue 5, September–October 2009, Pages 495-505 http://dx.doi.org/10.1016/j.intell.2009.06.003
- Journal of Biosocial Science (2009), 41:519-535 Cambridge University Press, Wealth, Intelligence, Politics and Global Fertility Differentials, Gerhard Meisenberg http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=5794948
- National IQ Means Transformed from Programme for International Student Assessment (PISA) Scores, and their Underlying Gene Frequencies, Volkmar Weiss, The Journal of Social, Political and Economic Studies 1.34(2009): pp. 71-94
- The impact of smart fractions, cognitive ability of politicians and average competence of peoples on social development. Heiner Rindermann, Michael Sailer, and James Thompson. Talent Development & Excellence Vol. 1, No. 1, 2009, 3-25