IQ and the Wealth of Nations

Infobox Book
name = "IQ and the Wealth of Nations"
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image_caption = "IQ and the Wealth of Nations" cover
author = Richard Lynn
Tatu Vanhanen
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language = English
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publisher = Praeger/Greenwood
pub_date = 2002
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"IQ and the Wealth of Nations" is a controversial 2002 book by Dr. Richard Lynn, Professor Emeritus of Psychology at the University of Ulster, Northern Ireland, and Dr. Tatu Vanhanen, Professor Emeritus of Political Science at the University of Tampere, Tampere, Finland.Lynn, R. and Vanhanen, T. (2002). IQ and the wealth of nations. Westport, CT: Praeger. ISBN 0-275-97510-X] The book argues that differences in national income (in the form of per capita gross domestic product) correlate with differences in the average national intelligence quotient (IQ). The authors interpret this correlation as showing that IQ is one important factor contributing to differences in national wealth and rates of economic growth, but that it is not the only determinant of these differences. The data, methodology, and conclusions have been criticized. [IQ_and_the_Wealth_of_Nations#Criticism] The 2006 book "IQ and Global Inequality" is a follow-up to "IQ and the Wealth of Nations".

Outline

The book includes the authors' calculation of average IQ scores for 81 countries, based on their analysis of published reports. It reports their observation that national IQ correlates with gross domestic product per capita at 0.82, and with the rate of economic growth from 1950-1990 at 0.64.

The authors believe that average IQ differences between nations are due to both genetic and economic factors. They also believe that low GDP can cause low IQ, just as low IQ can cause low GDP. (See: Positive feedback)

The authors write that it is the ethical responsibility of rich, high-IQ nations to financially assist poor, low-IQ nations, as it is the responsibility of rich citizens to assist the poor.

The book was cited several times in the popular press, notably the British conservative newspaper "The Times".Fact|date=April 2008 Because Tatu Vanhanen is the father of Matti Vanhanen, the Finnish Prime minister, his work has received wide publicity in Finland. It has also been severely criticized. [ [http://www.suz.unizh.ch/volken/ThomasVolken/pdfs/IQWealthNation.pdf The Impact of National IQ on Income and Growth: A Critique of Richard Lynn and Tatu Vanhanens Recent Book] by Thomas Volken ] [ [http://www.nature.com/hdy/journal/v92/n4/full/6800418a.html Book Review: IQ and the Wealth of Nations] Heredity April 2004, Volume 92, Number 4, Pages 359-360. K Richardson.]

National IQ estimates

Central to the book's thesis is a tabulation of what Lynn and Vanhanen believe to be the average IQs of the world's nations. Rather than do their own IQ studies (a potentially massive project), the authors average and adjust existing studies.

For 104 of the 185 nations, no studies were available. In those cases, the authors have used an estimated value by taking averages of the IQs of neighboring or comparable nations. For example, the authors arrived at a figure of 84 for El Salvador by averaging their calculations of 79 for Guatemala and 88 for Colombia. Including those estimated IQs, the correlation of IQ and GDP is 0.62.

To obtain a figure for South Africa, the authors averaged IQ studies done on different ethnic groups, resulting in a figure of 72. The figures for Colombia, Peru and Singapore were arrived at in a similar manner. For People's Republic of China, the authors used a figure of 109.4 for Shanghai and adjusted it down by an arbitrary 6 points because they believed the average across China's rural areas was probably less than that in Shanghai. Another figure from a study done in Beijing was not adjusted downwards. Those two studies formed the resultant score for China (PRC). For the figure of Macau, the average IQ is 104 which is obtained from the score of the Programme for International Student Assessment (PISA) and in such a way transformed into an IQ score [See Prenzel, Manfred et al. (eds).: PISA 2003. Münster: Waxmann 2004, p. 70, Table 2.9; or: PISA 2003: "A Profile of Student Performance in Mathematics"] .

In some cases, the IQ of a country is estimated by averaging the IQs of countries that are not actually neighbors of the country in question. For example, Kyrgyzstan's IQ is estimated by averaging the IQs of Iran and Turkey, neither of which is close to Kyrgyzstan – China, which is a geographic neighbor, is not counted as such by Lynn and Vanhanen. This presumably because the ethnic groups of the area speak Iranian and Turkic languages, but do not include Chinese.

To account for the Flynn effect (an increase in IQ scores over time), the authors adjusted the results of older studies upward by a number of points.

*The sovereignty of Hong Kong was returned to China by the United Kingdom in 1997. However, Hong Kong still maintains most of the colonial administrative system and hence appears in many "international" rankings.

pecial cases

In several cases, actual GDP did not correspond with that predicted by IQ. In these cases, the authors argued that differences in GDP were caused by differences in natural resources and whether the nation used a "planned" or "market" economy.

One example of this was Qatar, whose IQ was estimated by Lynn and Vanhanen to be about 78, yet had a disproportionately high per capita GDP of roughly USD $17,000. The authors explain Qatar's disproportionately high GDP by its high petroleum resources. Similarly, the authors think that large resources of diamonds explain the economic growth of the African nation Botswana, the fastest in the world for several decades.

The authors argued that the People's Republic of China's per capita GDP of roughly USD $4,500 could be explained by its use of a communist economic system for much of its recent history. The authors also predicted that communist nations who they believe have comparatively higher IQs, including the PRC, Vietnam, and North Korea, can be expected to gain GDP by moving from centrally-planned to market economic systems, while predicting continued poverty for African nations. Recent trends in the economy of the People's Republic of China and Vietnam seem to confirm this prediction, as China's GDP has grown rapidly since introducing market reforms. South Korea has a higher average IQ and a market economy. However, South Korea still has a lower GDP/Capita than many Western nations (but relatively high overall). Still, South Korea went from amongst the poorest nations in the world to advanced economy by recording among fastest growth rate in the world. Despite a supposedly higher average IQ and a market economy since the Meiji Restoration in 1867, Japan still has a lower GDP/Capita than many Western nations. Also, Sub-Saharan Africa is now having faster growth than Latin America and the Middle East, which seems to contradict the predictions.

The two most striking exceptions, however, may be Ireland and the United States. Ireland, whose average I.Q. is listed at 93, has the fourth highest per capita GDP (PPP adjusted) of any country in the world (after tiny Luxembourg, Norway and the United States). [ [http://stats.oecd.org/wbos/Default.aspx?usercontext=sourceoecd] OECD figures] for GDP PPP adjusted for 2005] [ [ GDP and GNI Ranking country performance is an interesting and useful exercise, but it can be misleading, in part because of what the indicators do not show] , [http://www.oecdobserver.org/info/about_us.php OECD Observer] , March 2005. "Ireland is another country where GDP has to be read with care. Ireland's position has risen up the GDP per head rankings since 1999, and is now in the top five countries in the OECD. This remarkable transformation has been put down to a mix of factors, of which inward investment in high value-added businesses is one. But does GDP per head accurately reflects Ireland’s actual wealth, since all that inward investment (and foreign labour) generates profits and other revenues, some of which inevitably flows back to the countries of origin?"] The United States, with an average I.Q. of 98, has the third-highest per capita GDP (PPP adjusted), and is by far the most populous of the richest 10 countries. Both of these countries have I.Q. averages considerably below those of countries such as South Korea, Taiwan, and Germany, but have per capita GDPs about 1.5 times higher.

Related studies

"IQ and the Wealth of Nations"' was not peer-reviewed before publication but was published by a publisher of academic literature. Peer reviewed articles have used the IQ scores presented in the book and some have also commented on the claims in the book.

Several negative reviews have been published in the scholarly literature. 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 questionably validity and are used in ways that cannot be justified." [Cite journal | journal = Contemporary Psychology: APA Review of Books | month = August | year = 2004 | volume = 49 | issue = 4 | pages = 389–396 | author = Barnett, Susan M. and Williams, Wendy | title = National Intelligence and the Emperor's New Clothes | url = http://psycinfo.apa.org/psyccritiques/display/?uid=2004-17780-001] They also wrote that cross country comparisons are "virtually meaningless." Ken Richardson wrote "This is not so much science, then, as a social crusade. The Pioneer Fund of America, champion of many dubious causes in the past, will obtain little credit from having assisted this one." [ [http://www.nature.com/hdy/journal/v92/n4/full/6800418a.html Heredity April 2004, Volume 92, Number 4, Pages 359-360] ] Thomas Nechyba wrote of "relatively weak statistical evidence and dubious presumptions." [Nechyba, T. (2004). Review of IQ and the Wealth of Nations. Journal ofEconomic Literature, 42, 220–221. (p. 220)] Astrid Ervik asked "are people in rich countries smarter than those in poorer countries?" and concluded that "the authors fail to present convincing evidence and appear to jump to conclusions." [Ervik, A. O. (2003). IQ and the Wealth of Nations. The Economic Journal, 113, No. 488, F406–F407.]

Denny Borsboom (2006) finds that mainstream contemporary test analysis does not reflect substantial recent developments in the field and "bears an uncanny resemblance to the psychometric state of the art as it existed in the 1950s." For example, it notes that "IQ and the Wealth of Nations", in order to show that the tests are unbiased, uses outdated methodology, if anything indicative of that test bias exist. [ [http://users.fmg.uva.nl/dborsboom/papers.htm The attack of the psychometricians] . DENNY BORSBOOM. PSYCHOMETRIKA VOL 71, NO 3, 425–440. SEPTEMBER 2006.]

Thomas Volken wrote that the study is "neither methodologically nor theoretically convincing." ["The Impact of National IQ on Income and Growth" [http://www.suz.unizh.ch/volken/ThomasVolken/pdfs/IQWealthNation.pdf] ] Although critical of the IQ data, for the sake of argument Volken assumes that the data is correct but then criticizes the statistical methods used, finding no effect on growth or income. Using the same assumption, Garett Jonesand W. Joel Schneider report a strong connection between intelligence and economic growth. [cite journal | title = Intelligence, Human Capital, and Economic Growth: An Extreme-Bounds Analysis | url = http://www.siue.edu/~garjone/JonesSchneApr.pdf | author = Jones, G, Schneider, WJ | volume = Forthcoming | journal = Journal of Economic Growth | year = 2006 | format = dead link|date=June 2008 – ^{[http://scholar.google.co.uk/scholar?hl=en&lr=&q=intitle%3AIntelligence%2C+Human+Capital%2C+and+Economic+Growth%3A+An+Extreme-Bounds+Analysis&as_publication=Journal+of+Economic+Growth&as_ylo=2006&as_yhi=2006&btnG=Search Scholar search]} ]

Erich Weede and Sebastian Kampf wrote that "there is one clear and robust result: average IQ does promote growth." [Weede, E. and Kämpf, S. (2002). The Impact of Intelligence and Institutional Improvements on Economic Growth. Kyklos, 55, Fasc. 3, 361–380. (p. 376)] Edward Miller wrote that "the theory helps significantly to explain why some countries are rich and some poor." [Miller, E. (2002). Differential Intelligence and National Income. A review of IQ and the Wealth of Nations. Journal of Social, Political & Economic Studies, 27, 413–524. (p. 522)] Michael Palairet wrote that "Lynn and Vanhanen have launched a powerful challenge to economic historians and development economists who prefer not to use IQ as an analytical input." [Palairet, M. R. (2004). Book review, IQ and the Wealth of Nations. Heredity, 92, 361–362.] In a reanalysis of the Lynn and Vanhanen's hypothesis, Dickerson (2006) finds that IQ and GDP data is best fitted by an exponential function, with IQ explaining approximately 70% of the variation in GDP. [cite journal | author = Dickerson, R. E. | year = 2006 | month = May-June | title = Exponential correlation of IQ and the wealth of nations | journal = Intelligence | volume = 34 | issue = 3 | pages = 291–295 | id = | doi = 10.1016/j.intell.2005.09.006 ] Dickerson concludes that as a rough approximation "an increase of 10 points in mean IQ results in a doubling of the per capita GDP."

Whetzel and McDaniel (2006) conclude that the book's "results regarding the relationship between IQ, democracy and economic freedom are robust". [cite journal | author = Whetzel, D. L. & McDaniel, M. A. | year = 2006 | month = September-October | title = Prediction of national wealth | journal = Intelligence | volume = 34 | issue = 5 | pages = 449–458 | doi = 10.1016/j.intell.2006.02.003 [http://www.people.vcu.edu/~mamcdani/Publications/Whetzel%20&%20McDaniel%20(2006,%20Intelligence)%20Prediction%20of%20national%20wealth.pdf PDF] ] Moreover, they address "criticisms concerning the measurement of IQ in purportedly low IQ countries", finding that by setting "all IQ scores below 90 to equal 90, the relationship between IQ and wealth of nations remained strong and actually increased in magnitude." On this question they conclude that their findings "argue against claims made by some that inaccuracies in IQ estimation of low IQ countries invalidate conclusions about the relationship between IQ and national wealth."

Voracek (2004) used the national IQ data to examine the relationship between intelligence and suicide, finding national IQ was positively correlated with national male and female suicide rates. [cite journal | author = Voracek, M. | year = 2004 | month = | title = National intelligence and suicide rate: an ecological study of 85 countries | journal = Personality and Individual Differences | volume = 37 | issue = 3 | pages = 543–553 | id = | doi = 10.1016/j.paid.2003.09.025 ] The effect was not attenuated by controlling for GDP.

Barber (2005) found that national IQ was associated with rates of secondary education enrollment, illiteracy, and agricultural employment. [cite journal | author = Barber, N. | year = 2005 | month = | title = Educational and ecological correlates of IQ: A cross-national investigation | journal = Intelligence | volume = 33 | issue = 3 | pages = 273–284 | id = | doi = 10.1016/j.intell.2005.01.001 ] The effect on illiteracy and agricultural employment remained with national wealth, infant mortality, and geographic continent controlled.

Both Lynn and Rushton have suggested that high IQ is associated with colder climates. To test this hypothesis, Templer and Arikawa (2006) compare the national IQ data from Lynn and Vanhanen with data sets that describe national average skin color and average winter and summer temperatures. [cite journal | author = Templer, D. I. and Arikawa, H. | year = 2006 | month = | title = Temperature, skin color, per capita income, and IQ: An international perspective | journal = Intelligence | volume = 34 | issue = 2 | pages = 121–139| id = | doi = 10.1016/j.intell.2005.04.002 see also discussion [http://theoccidentalquarterly.com/vol4no3/dt-tbc.html] ] They find that the strongest correlations to national IQ were −0.92 for skin color and −0.76 for average high winter temperature. They interpret this finding as strong support for IQ-climate association. Other studies using different data sets find no correlation [http://www.pnas.org/cgi/content/full/101/35/12824] [http://dienekes.angeltowns.net/articles/greekiq/] .

Kanazawa (2006), "IQ and the wealth of states" (in press in "Intelligence"), replicates across U.S. states Lynn and Vanhanen's demonstration that national IQs strongly correlate with macroeconomic performance. [cite journal | author = Kanazawa, S. | year = 2006 | month = | title = IQ and the wealth of states | journal = Intelligence | volume = 34 | issue = 6 | pages = 593–600 | id = | doi = 10.1016/j.intell.2006.04.003 | format = | accessdate = ] Kanazawa finds that state cognitive ability scores, based on the SAT data, correlate moderately with state economic performance, explaining about a quarter of the variance in gross state product per capita.

Hunt and Wittmann (in press) use data from the Program for International Student Assessment (PISA) to conclude that "in spite of the weaknesses [in] several of their data points Lynn and Vanhanen's empirical conclusion was correct, but we question the simple explanation that national intelligence causes national wealth. We argue that the relationship is more complex". [cite journal | author = Hunt, E., Wittmann, W. | year = in press | month = | title = National intelligence and national prosperity | journal = Intelligence | volume = 36| issue = | pages = 1| id = | doi = 10.1016/j.intell.2006.11.002]

The book was followed by Lynn's 2006 "Race Differences in Intelligence", which expands the data by nearly four times and concludes the average human IQ is presently 90 when compared to a norm of 100 based on UK data, or two thirds of a standard deviation below the UK norm, and Lynn and Vanhanen's 2006 "IQ and Global Inequality". [Lynn, R. and Vanhanen, T. (2006). IQ and global inequality. Athens, GA: Washington Summit Books. see also cite journal | author = Lynn, R., & Mikk, J. | title = National differences in intelligence and educational attainment | journal = Intelligence | volume = In Press, Corrected Proof. | doi = 10.1016/j.intell.2006.06.001 | year = 2007 | pages = 115]

Jared Diamond's "Guns, Germs and Steel" instead argues that historical differences in economic and technological development for different areas can be explained by differences in geography (which affects factors like population density and spread of new technology) and differences in available crops and domesticatable animals. Richard Nisbett argues in his 2004 "The Geography of Thought" that some of these regional differences shaped lasting cultural traits, such as the collectivism required by East Asian rice irrigation, compared with the individualism of ancient Greek herding, maritime mercantilism, and money crops wine and olive oil (pp. 34-35).

Criticism

Criticism of Research Funding Sources

Lynn has been frequently criticized as a Pioneer fund grantee.

Criticism of Dubious Data Sets

The figures were obtained by taking unweighted averages of different IQ tests. The number of studies is very limited; the IQ figure is based on one study in 34 nations, two studies in 30 nations. There were actual tests for IQ in 81 nations. In 104 of the world's nations there were no IQ studies at all and IQ was estimated based on IQ in surrounding nations. [ [http://www.suz.unizh.ch/volken/ThomasVolken/pdfs/IQWealthNation.pdf The Impact of National IQ on Income and Growth: A Critique of Richard Lynn and Tatu Vanhanens Recent Book] by Thomas Volken ] The number of participants in each study was usually limited, often numbering under a few hundred. The exceptions to this were the United States and Japan, for which studies using more than several thousand participants are available.

Many nations are very heterogeneous ethnically. This is true for many developing countries. It is very doubtful that an often limited number of participants from one or a few areas are representative for the population as whole.

Studies that were averaged together often used different methods of IQ testing, different scales for IQ values and/or were done decades apart. IQ in children is different although correlated with IQ later in life and many of the studies tested only young children.

A test of 108 9-15-year olds in Barbados, of 50 13-16-year olds in Colombia, of 104 5-17-year olds in Ecuador, of 129 6-12-year olds in Egypt, of 48 10-14-year olds in Equatorial Guinea, and so on, all were taken as measures of 'national IQ'. [ [http://www.nature.com/hdy/journal/v92/n4/full/6800418a.html Book Review: IQ and the Wealth of Nations] Heredity April 2004, Volume 92, Number 4, Pages 359-360. K Richardson.]

The notion that there is such a thing as a culturally neutral intelligence test is disputed. [ [https://www.tcrecord.org/Content.asp?ContentID=1544 "The Cultural Context of Learning and Thinking: An Exploration in Experimental Anthropology"] Gay, Glick and Sharp (1971) made the following observation: "Cultural differences in cognition reside more in the situations to which particular cognitive processes are applied than in the existence of a process in one cultural group, and its absence in another." A similar position is held by Berry in "Acculturative Stress" 1974 [http://jcc.sagepub.com/cgi/content/abstract/5/4/382] ] ["Educational Handicap, Public Policy, and Social History: A Broadened Perspective on Mental Retardation" ISBN 0029279208 Sarason and Doris (1979) view intelligence as a cultural invention that does not hold true across cultures.] [ [http://www.blackwell-synergy.com/doi/abs/10.1111/j.1468-2389.2006.00346.x 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] [ [http://asm.sagepub.com/cgi/content/abstract/12/3/303 Culture-Fair Cognitive Ability Assessment] Steven P. Verney Assessment, Vol. 12, No. 3, 303-319 (2005)] [ [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15742541&dopt=Abstract Cross-cultural effects on IQ test performance: a review and preliminary normative indications on WAIS-III test performance.] Shuttleworth-Edwards AB, Kemp RD, Rust AL, Muirhead JG, Hartman NP, Radloff SE. J Clin Exp Neuropsychol. 2004 Oct;26(7):903-20.] There are many difficulties when one is measuring IQ scores across cultures, and in multiple languages. Use of the same set of exams requires translation, with all its attendant difficulties and possible misunderstandings in other cultures. [Instruments developed to quantify smartness are culturally based and cannot simply be "transplanted" to a culture with different values (Greenfield, 1997). In "Culture as process: Empirical methods for cultural psychology"] To adapt to this, some IQ test rely on non-verbal approaches, which involve pictures, diagrams, and conceptual relationships (such as "in-out", "big-small", and so on).

Criticism of Data Set Sources and their Accuracy

There are also errors in the raw data presented by authors. The results from Vinko Buj's 1981 study of 21 European cities and the Ghanaian capital Accra used different scaling from Lynn and Vanhanen's. A comparison of the reported to actual data from only a single study found 5 errors in 19 reported IQ scores. [ [http://dienekes.blogspot.com/2004/08/richard-lynns-massaged-iq-data.html Richard Lynn's Massaged IQ Data] ] [ [http://dienekes.angeltowns.net/articles/greekiq/ Greek IQ] by Dienekes Pontikos]

The national IQ of Ethiopia was estimated from a study done on 250 fifteen years old Ethiopian Jews one year after their migration to Israel. The research compares their level of performance with native Israelis using progressive matrices tests. It is strange that the data used to represent the "IQ of Ethiopia" are restricted to a tiny ethnic minority in Ethiopia, and that the tests were not even conducted in Ethiopia. Furthermore, one study showed that after intensive training, the cognitive ability of Ethiopian Jewish immigrants improved and caught up with that of their native Israeli peer groups. [Kaniel, S and Fisherman S. (1991). Level of performance and distribution of errors in the progressive matrices test: a comparison of Ethiopian immigrant and native Israeli adolescents. International Journal of Psychology, 26, 25-33]

Criticism of Subjective Statistical Manipulation by Authors

As noted earlier, in many cases arbitrary adjustments were made by authors to account for the Flynn effect or when the authors thought that the studies were not representative of the ethnic or social composition of the nation.

One critic writes: "Their scheme is to take the British Ravens IQ in 1979 as 100, and simply add or subtract 2 or 3 to the scores from other countries for each decade that the relevant date of test departs from that year. The assumptions of size, linearity and universal applicability of this correction across all countries are, of course, hugely questionable if not breathtaking. Flynn's original results were from only 14 (recently extended to twenty) industrialised nations, and even those gains varied substantially with test and country and were not linear. For example, recent studies report increases of eight points per decade among Danes; six points per decade in Spain; and 26 points over 14 years in Kenya (confirming the expectation that newly developing countries would show more rapid gains)." [ [http://www.nature.com/hdy/journal/v92/n4/full/6800418a.html Book Review: IQ and the Wealth of Nations] Heredity April 2004, Volume 92, Number 4, Pages 359-360. K Richardson.]

There is controversy about the definition and usage of IQ and intelligence. See also race and intelligence.

It is generally agreed many factors, including environment, culture, demographics, wealth, pollution, and educational opportunities, affect measured IQ. [ [http://faculty.mwsu.edu/psychology/Laura.Spiller/4503_Tests/intelligence_knowns_and_unknowns.pdf] Intelligence: Knowns and Unknowns] See also Health and intelligence.

Finally, the Flynn effect may well reduce or eliminate differences in IQ between nations in the future. One estimate is that the average IQ of the US was below 75 before factors like improved nutrition started to increase IQ scores. Some predict that considering that the Flynn effect started first in more affluent nations, it will also disappear first in these nations. Then the IQ gap between nations will diminish. However, even assuming that the IQ difference will disappear among the babies born today, the differences will remain for decades simply because of the composition of the current workforce. Steve Sailer noted as much when discussing the workforce in both India and China (see second diagram) [http://www.vdare.com/sailer/060423_lynn.htm] .

References

ee also

*"IQ and Global Inequality"
*"The Bell Curve"
*Race and intelligence
*Economic inequality

External links

* [http://www.rlynn.co.uk/pages/article_intelligence/1.asp "Intelligence and the Wealth and Poverty of Nations"] - article by Lynn and Vanhanen
* [http://www.isteve.com/IQ_Table.htm 2002 ("IQ and the Wealth of Nations") data]
* [http://www.volkmar-weiss.de/table.html PISA scores transformed into IQ values in comparison with IQ estimated by Lynn and Vanhanen]
* [http://www.iapsych.com/articles/dickerson2006ip.pdf Exponential correlation of IQ and the wealth of nations] - Peer reviewed article to be published in an upcoming edition of Intelligence (journal)
* [http://www.ssc.uwo.ca/psychology/faculty/rushtonpdfs/L&Vreview.pdf "The Bigger Bell Curve: Intelligence, National Achievement, and The Global Economy"] , review by J. Philippe Rushton
* [http://rpongett.phpwebhosting.com/gdp.html "A Reader's statistical update of IQ & The Wealth of Nations"]
* [http://www.vdare.com/sailer/wealth_of_nations.htm A Few Thoughts on IQ and the Wealth of Nations] , Steve Sailer, "VDARE", April 2002.