HVGIQ: Vietnam

Richard Lynn and Tatu Vanhanen did not have a study for Vietnam in IQ and the Wealth of Nations (2002). Then, beginning with their follow-up book, IQ and Global Inequality (2006), Lynn added a bogus study for Vietnam and gave the world’s 13th most populous country a made-up national IQ of 94. In short, Lynn’s dataset does not have an IQ study for Vietnam.

In this post I review two dozen intelligence and achievement test studies for Vietnam and Vietnamese populations living internationally. While IQ in Vietnam is lower than I anticipated, there is evidence that Vietnamese people have high intellectual potential.

⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻ HᏤ ⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻

Intelligence Test Studies in Vietnam

First, let’s address Lynn’s study for Vietnam. In IQ and Global Inequality (p. 313), he notes: “The IQ of 94 is given by Flynn (1991) for Vietnamese immigrants in the United States.” The citation is to James Flynn’s book Asian Americans: Achievement beyond IQ.

I’m not thrilled about the use of immigrant scores for a national IQ, but we can set this issue aside for a larger problem: Flynn’s book doesn’t even give an IQ score for Vietnamese immigrants. In his review of Asian American IQ studies, Flynn summarizes some obscure data published in a Raven’s Progressive Matrices technical manual: An anonymous scholar collected some RPM data in an anonymous city in West-Central America. Based on regional demographic data, Flynn surmises that those classified as Asian Americans in this study were possibly up to 60% mainland Southeast Asian, with many of these being recent refugees from Vietnam, Laos, and Cambodia. It’s quite a stretch to re-classify a diverse American mish mash of Asian ethnic groups as “Vietnamese immigrants.”

Later on I’ll discuss several actual studies of Vietnamese immigrant IQ that Lynn could have used instead.

Most of the studies in Vietnam are newer than IQ and the Wealth of Nations, but there are a few exceptions from the Vietnam War era.

In the oldest study, Susan Mayer (1966 ) used her husband’s local military contacts to help her remotely administer the Draw-a-Man test to schoolchildren in South Vietnam. Their village, near Saigon, was 95% Catholic, and was mostly composed of refugees from the Communist North.

Sister Rose, a local teacher who was educated in America, administered the test according to the instructions in the manual. The children, ages 8-12, were all poor peasants with no experience drawing pictures, so they were given a practice round to get familiar with the task. Nevertheless this small sample of 47 children had a Draw-a-Man IQ of 98.9, virtually the same as American children.

A second study, conducted by the U.S. military, compared 82 Vietnamese and 31 U.S. helicopter mechanics on a battery of nonverbal ability tests (Guthrie et al, 1971 ). Seven different abilities were assessed with 11 sub-tests from French’s Kit of Reference Tests. Performance was similar for the two groups on most tests, but the Vietnamese airmen scored about 1½ standard deviations lower than the Americans on the tool knowledge test. This might’ve been related to difficulty interpreting the two-dimensional test drawings. Their comparative IQ was 96.6 (or 92.5, if we use the French’s Kit norms). However, I’m marking this as a mildly unrepresentative sample— the subjects were all high school graduates working in the Vietnamese airforce.

■ The Young Lives study

The literature on Vietnam is then silent for many years until the Young Live project in the 2000s. Young Lives is a large longitudinal study that is collecting cognitive data for some 14,000 children from Ethiopia, India, Peru, and Vietnam. The children will be tested five times over a 14 period, from 2002 to 2016, with the fourth round of testing beginning this year.

The first YL report was published in 2003. Raven’s Progressive Matrices were administered to a cohort of 1000 8 year olds in each country (Tuan et al, 2003 ). However, the children in Ethiopia and Peru had too many problems with the test, so the scores are not reported, and the test was discontinued from the study.

The second round of testing occurred in 2006, and a full report of this data wasn’t available until fairly recently. Glewwe et al (2012 ) report raw scores for a translated version of the Peabody Picture Vocabulary Test. The 8 year olds from the first round of testing are now 12 and their IQ on the PPVT is 95.3.

This data is also roughly broken down by ethnicity. The Kinh are the majority ethnic group in Vietnam, comprising some 86% of the population, and their IQ on the PPVT is 98.3.

Some of the larger ethnic groups in Vietnam are Thais, Khmer, Chinese, and Hmong. But the data for minorities are lumped together under just two categories: those who speak Vietnamese, and those who speak minority languages. The PPVT score of the first group was 82.3, and the PPVT score of the second group was 64.3.

A larger cohort of children who were 1 year old during the first round of testing, were also included for round 2 testing. This group of 1,747 5 year olds had a (much lower) PPVT IQ of 82.3.

For this cohort, the Kinh majority had an IQ of 84.3. Vietnamese speaking minorities had a score of 75.3, and non-Vietnamese speaking minorities had a score of 65.3.

Data from the third round of YL testing, which occurred in 2009, is spread across three recent reports:

Behrman et al (2013 ) report scores for 1,602 children in the younger cohort, who are now 8 years old. Their latest PPVT IQ is 85.4.

Fink & Rockers (2014 ) report scores for 976 children in the older cohort, who are now 15 years old. Their latest PPVT IQ is 102.4.

Cueto & Leon (2012 ) also discuss psychometric equivalence. It’s noteworthy that there is minimal differential item functioning for the Vietnamese translation of the PPVT: only one item was removed for the older cohort, and no items were removed for the younger cohort.

Cueto & Leon also report that PPVT scores in the younger sample have correlations of .28 with father’s education, .29 with mother’s education, and .36 with family wealth.

The proper interpretation of Young Lives will be difficult until round 4 data is released. Looking at just the older cohort we see a score of 95.3 at age 12 and a score of 102.4 at age 15.

Looking at just the younger cohort we see a score of 82.3 at age 5, and a score of 85.4 at age 8.

The large difference between these two closely spaced birth cohorts from the same regions might suggest either 1) a bizarre sudden decline in national IQ, or 2) a bizarre jump in Vietnamese cognitive development that occurs around puberty.

Either way a simple average of the scores feels like an inadequate summary of Vietnam’s IQ. Scores are increasing for both cohorts, so if there is a large jump in the younger cohort’s IQ in round 4, it might make sense to give a greater weight to studies with older children. Until that time, the current mean IQ from the YL project is 91.4.

■ Three more intelligence studies for Vietnam

A fourth study of intelligence in Vietnam is Watanabe et al (2005 ). 311 rural children, age 8, from the Thanh Hoa province, were tested with the Colored Progressive Matrices.

The average IQ of these children was 82.4, which is similar to the IQ of children at this same age in the YL sample.

A fifth study of intelligence in Vietnam is Nga et al (2011 ). 469 children, also age 8, from the Hung Yen province, were tested with the Colored Progressive Matrices as well as several performance sub-tests from the Wechsler Intelligence Scale for Children.

IQ on the CPM was 82.6. IQ on the WISC was 82.5.

A sixth study of intelligence in Vietnam is Rindermann et al (2013 ). 60 children, age 11, from two different cities in north and south Vietnam, were given the Cognitive Ability Test.

Rindermann provides raw scores as well as several different kinds of standard score estimates. I choose to calculate an IQ from the test’s German norms and add a 16 year Flynn adjustment, giving this sample an IQ of 97.3.

Table I: IQ test scores in Vietnam

Admin Sample Age N Test IQ Reference
1965 A 8-12 47 DAM 99 Mayer, 1966
1969 SA 20-22 82 FKRT 97 Guthrie et al, 1971
2004 A 8 311 CPM 82 Watanabe et al, 2005
2006 A 5 1747 PPVT 82 Glewwe et al, 2012
2009 8 1602 85 Behrman et al, 2013
2006 A 12 945 PPVT 95 Glewwe et al, 2012
2009 15 976 102 Fink & Rockers, 2013
2007 A 8 469 CPM 83 Nga et al, 2011
2013 A 11 60 CogAT 97 Rindermann et al, 2013

This leaves us with six IQ studies and seven different samples for Vietnam (Table I). Three different samples of 8 year olds show a remarkable similarity across four tests: PPVT = 85.4 (Glewwe et al, 2012), CPM = 82.4 (Watanabe et al 2005), and CPM = 82.6 and WISC = 82.5 (Nga et al, 2011).

It also seems consistent that Young Lives found an IQ of 95.3 for a sample of 12 year olds and Rindermann et al (2013) showed an IQ of 97.3 for 11 year olds.

This is all suggestive that IQ increases over time for Vietnamese children (“cumulative advantage”), perhaps reaching 100 or higher by later adolescence as seen in the older YL cohort (Fink & Rockers, 2014). More research is needed.

Using the median, the average IQ for Vietnam from 6 normal samples is 91.4.

Achievement Tests in Vietnam

In 2001 the Vietnam Ministry of Education and Training (MoET), in collaboration with various NGOs, administered math and reading tests to over 70,000 5th grade students from all across the country.

These tests had a number of items that were similar to or taken directly from TIMSS, one of the major worldwide student achievement tests. The researchers used these common items as a bridge between the two tests in order to evaluate Vietnam’s performance in a global context (World Bank, 2004, pp. 534-543 ). One obstacle to a straightforward comparison is that the TIMSS children were in a lower school grade. The Vietnamese 5th graders performed like the Hong Kong 4th graders at the top of the test rankings, but depending on how much these scores increase with age, this could mean anything from a really good to a really bad performance. The researchers cautioned against over-interpretation and kept their conclusions vague, but their emphasis on Vietnam’s rank next to TIMSS’ top performers, suggested this was preliminary evidence that the country had relatively talented students.

Vietnam only recently participated in a cross-national study of student achievement with the Programme for International Student Assessment (PISA) 2012. When the results were released in December 2013, Vietnam’s high international ranking was reported with much fanfare.

Table II shows that when their scores are converted into an Achievement Quotient—with the United Kingdom set at 100—Vietnam has a PISA AQ of 102.4 (OECD, 2013 ).

Table II: AQ test scores in Vietnam

Admin Sample Age N Test AQ Reference
2012 SA 15 4959 PISA 102 OECD, 2013


On the one hand, the sample was 15 years old and this is consistent with the IQ data that suggests older Vietnamese children perform at the level of Western European children.

On the other hand, it is also suspicious how well these single-party Communist remnants do on international achievement rankings. (See my post on Cuba for another example.)

A more identifiable problem is that secondary students in Vietnam are a more elite portion of the population than their counterparts in developed nations: “The World Bank reports that in 2010 the gross enrolment rate at upper-secondary schools in Vietnam was just 65%, compared with 89% and 98% in America and Britain, respectively. South Korea’s rate was 95%.” A related problem is that Vietnam had one of the worst rates of sample attrition among the participating nations.

This is not to say that the Vietnam (or China… or even Cuba) achievement rankings are necessarily wrong or need to be dismissed. This issue shows one reason why it is important to take a holistic approach to the cognitive literature, despite the obvious psychometric advantages of tests like PISA and TIMSS: intelligence test results come from many independent sources.

One ‘Big Data’ advantage of these international achievement tests is the large, nation-wide samples, which permit finer “state”-level analyses for many different nations (e.g. Italy, Spain, Germany, Mexico, & Brazil). While I am not aware of PISA releasing such data for Vietnam, the 2001 MoET study did report reading scores for all Vietnamese provinces (World Bank, 2004, p. 572). I’ve fit these scores to Vietnam’s PISA AQ score of 102.1, and placed them into two maps below: Figure I shows the AQ level of all 61 Vietnam provinces, while Figure II shows the 8 major regions of Vietnam, along with their corresponding AQs.

Heiner Rindermann (2013) found a three point advantage for a small sample of children in the city of Pleiku (located in the Central Highlands region in the South) over the children from Hai Phong (located in the Red River Delta region in the North). But the MoET results reveal higher performance in the North than in the South: the average AQ of the North Vietnam provinces is 102.4, while the average AQ of the South Vietnam provinces is 100.3. The highest scores were from the Red River Delta in the North, which includes the nation’s capital, Hanoi. The lowest scores were in the Mekong River Delta in the far south.

This is consistent with a cognitive pattern found within many nations (including the US, Brazil, Japan, Mexico, Italy, and Spain)—and within and between continents—where test scores are higher in the northern regions than in the southern regions. The correlation between MoET performance and latitude for all 61 Vietnam provinces is .33. For comparison, the (intraracial) correlation between NAEP performance and latitude for the 50 U.S. states is .52 (Epigone, 2007). And the correlation between achievement test scores and latitude for 47 Japanese prefectures is .44 (Kura, 2013).

The geography of intelligence could point to an intensifying selection pressure for cognitive ability at more temperate latitudes, and/or the biological consequences of increasing parasitic insults at lower latitudes. If intellect is a source of martial leverage, this could be relevant to a historical pattern of invasion and conquest running from north to south (Hart, 2007).

Intelligence and achievement test scores of the Vietnamese diaspora

■ Vietnamese Americans
There are 1.7 million Vietnamese Americans, making them the fourth largest Asian American ethnic group. Yet there were hardly any Vietnamese people living in the United States prior to the Fall of Saigon in 1975 (only 650 arrivals between 1950-1974). The first wave of Vietnamese refugees, numbering about 125,000, was largely made up of educated professionals with former roles in the South Vietnam establishment. The U.S. government aided their escape. A second, larger wave of mostly poor and uneducated immigrants (called “boat people”) began arriving from 1978-1980s.

The first intelligence study for Vietnamese Americans is an early snapshot of this second wave of refugees. Joseph Delatte (1978 ) tested 93 children, ages 5-10, with the Goodenough Draw-a-Man test. The sample had only been in the country for about 6 months, so the instructions were translated into Vietnamese. Their IQ on this test was 101.4. This parallels the performance of the South Vietnamese children tested by Mayer (1966) over a decade earlier.

Another study from this period of high immigration looked at a disadvantaged sample of low SES, non-English speaking Vietnamese preschoolers (Milan, 1983 ). Marjorie Milan randomly selected 20 children with these characteristics from school enrollment records in Denver, Colorado. Prior to their entry into kindergarten, Milan tested the children in their homes with the aid of an interpreter. Their IQ on the Columbia Mental Maturity Scale was 99.4.

Vietnamese Americans are less than 1% of the U.S. population, but small numbers of Vietnamese children can be found in larger datasets. I analyzed the National Longitudinal Study of Adolescent Health (Malloy, 2014a). This is a representative survey of high school students from 1995. Add Health contains 19 Vietnamese adolescents, and their IQ on the Peabody Picture Vocabulary Test is 83.2.

I also looked at the SWEEP dataset (Study of State-Wide Early Education Programs). This is combined data from two major studies on the effects of pre-k programs in 11 states. This dataset contains 23 Vietnamese preschoolers that were tested on the PPVT in 2003. Their IQ on this test was 85.7 (Malloy, 2014b).

Dick et al (2002 ) looked at Vietnamese Americans on the other end of the lifespan. Seniors from various ethnicities in Southern California were recruited to establish sub-group norms for an experimental test battery containing the block design and digit span subtests from the Wechsler Adult Intelligence Scale-Revised. On average, the 61 Vietnamese participants were 71.5 years old and had only been in the country for 3 years. Virtually none of this sample spoke English. They had a WAIS IQ of 99.5.

Urdan & Giancarlo (2001 ) administered the Naglieri Noverbal Ability Test to 145 Vietnamese American high school students in California. These students had an IQ of 101.3.

The most recent study for Vietnamese Americans is Pham & Kohnert (2014 ), who tested a group of bilingual 1st graders in Florida. 55% of the sample was U.S. born, and immigrants had arrived, on average, at age 3. Their IQ on the Test of Nonverbal Abilities was 107.7.

This gives us seven different samples for Vietnamese Americans (Table III). Even though the preschool children in the study by Milan (1983) had an average IQ, they were selected for disadvantaged traits, so they are a relatively unfit sample.

Taking the median average of six normal samples gives us an IQ of 100.7 for Vietnamese Americans


Table III: IQ test scores for Vietnamese Americans

Admin Sample Age N Test IQ Reference
1978 A 5-10 93 DAM 101 Delatte, 1978
1982 SD 5-6 20 CMMS 99 Milan, 1983
1995 A 16 19 PPVT 83 Malloy, 2014a
2000 A 16 145 NNAT 101 Urdan & Giancarlo, 2001
2003 A 5 23 PPVT 84 Malloy, 2014b
2001 A 72 61 WAIS 100 Dick et al, 2002
2008 A 7 33 TONI 108 Pham & Kohnert, 2014

Standardized achievement tests—objective measures of learned academic material—provide an alternative, but similar way of revealing intellectual talent and potential.

Some 38% of Vietnamese Americans live in California, which is convenient for our purposes here because California gives state-wide achievement tests to nearly all school children, and this data is broken down by ethnicity and available online: Standardized Testing and Reporting (STAR).

For the years 2003-2006 I looked at the performance of over 240,000 Vietnamese Americans on the reading and math sections of the California Achievement Test. In comparison with whites, Vietnamese students had an AQ of 100.6 (Reading=97.7, Math=103.5).

For the years 2009-2012 I looked at the performance of over 250,000 Vietnamese Americans on the math and reading sections of the California Standards Tests. In comparison with whites, Vietnamese students had an AQ of 103.8 (Reading=101.6, Math=106).

An earlier and much smaller amount of data is also available from the Children of Immigrants Longitudinal Study, which gave the Stanford Achievement Test to 372 Vietnamese school children living in San Diego, CA in 1992 (Portes & MacLeod, 1996 ). Their AQ was 99.6 (Reading=95.4, Math=103.8).

The earliest and smallest study by Ima & Rumbaut (1989 ), reports Comprehensive Test of Basic Skills scores for 99 Vietnamese students in San Diego. This sample had an AQ of 98.7 (Reading=91.6, Math=106.1).

The median AQ from the four sources of data is 100.6 (R=96.6, M=103.7). This is virtually identical to the average from the IQ studies.

The average leaves out part of the story: there has been an upward trend in Vietnamese American achievement test performance since the 1980s, and it hasn’t stopped. For example, the most recent year with data on the California Standards Tests—2012—shows an AQ of 104.9.

Table IV: Achievement scores for Vietnamese Americans

Admin Sample Age N Test AQ Reference
1987 A 12-18 99 CTBS 99 Ima & Rumbaut, 1989
1992 A 14 372 StAT 100 Portes & MacLeod, 1996
2003-06 A 8-17 243288 CAT 101 Malloy, 2014c
2009-12 A 8-17 258119 CST 104 Malloy, 2014d

■ Chinese-Vietnamese Americans

Are Chinese people from Vietnam responsible for the high test scores of Vietnamese immigrants? Richard Lynn has suggested this numerous times. For example:

a) When addressing how Southeast Asians outperformed whites in the National Educational Longitudinal Study, he states that its “probably because many of [them] are ethnic Chinese-Vietnamese” (Lynn, 2008, p. 272).

b) He uses the over-representation of Vietnamese Australians in higher education as evidence for ‘East Asian’ ability by asserting that they are “mainly ethnic Chinese” (Lynn, 2008, pp. 51-52).

c) In his discussion of the Clark & Hanisee (1982) transracial adoption study—which showed a high IQ for a sample that was about half Vietnamese—Lynn simply asserts that the babies were “largely Chinese” (Lynn, 2006, p.139). This is not stated in the paper. He is (I assume) extrapolating from the fact that the adoptees came from the first wave of refugees in 1975. [1]

Lynn is relying on innuendo and inaccuracy, but this is a legitimate issue: there is both psychometric and sociological evidence that Chinese populations in Southeast Asia have high intelligence. Amy Chua describes their status in Vietnam at the beginning of the war: “The magnitude of the Chinese minority’s economic power was astounding. Constituting just 1 percent of Vietnam’s population, the Chinese controlled an estimated 90 percent of non-European private capital in the mid-1950s and dominated Vietnam’s retail trade, its financial, manufacturing, and transportation sectors, and all aspects of the country’s rice economy” (Chua, 2003, p. 33-34).

It is also true that a significant fraction of the Vietnamese diaspora was ethnic Chinese, but this doesn’t permit intellectual laziness. For example, there were 18,000 Chinese in the initial 1975 wave of refugees out of Vietnam, which was only about 14% of the total (Trieu, 2013, p. 306). The first wave of Vietnamese immigrants was not “largely Chinese” or even close.

It was actually the second wave out of Vietnam that marked the most intense period of Chinese immigration: Approximately 40% of the Vietnamese boat people arriving in the late 70s-early 80s were Chinese minority (Caplan et al, 1991, p. 45). However, Chinese-Vietnamese immigration also slowed rapidly: about 40% of all Chinese-Vietnamese in the U.S. today arrived between 1979-1981 (Rumbaut, 2007, p. 659). And yet the total Vietnamese population has nearly tripled since 1990; Chinese-Vietnamese are an ever-shrinking part of the Vietnamese American population.

Currently, there are about 200,000 Chinese-Vietnamese in the U.S. out of 1,737,433 Vietnamese Americans, or about 11.5% of the total. (Trieu, 2013, p. 306).

This small fraction can’t account for very much of our estimates. If we assume Chinese-Vietnamese have an IQ of 106, this still implies that majority Vietnamese Americans have an IQ of 100.

Further, Vietnamese American AQ scores have crept upwards as the population has expanded since the 1990s, coinciding with a period when Chinese-Vietnamese were an ever declining fraction of that population.

Finally, there is no evidence that Chinese-Vietnamese even have higher ability than the Kinh population, and U.S. immigrant data suggests either no difference or higher ability for majority Vietnamese. An apples-to-apples study of 536 second-wave refugees actually found better school performance for the Vietnamese majority than for the Chinese minority (Caplan et al, 1991, pp.16-17). The refugee children had an overall AQ of 101.5 on the California Achievement Test, and there were no differences between the Lao, Chinese-Vietnamese, and Kinh ethnic groups (according to the authors anyway … the ethnic scores are not reported).

Ima & Rambaut (1989) also compare the performance of Chinese-Vietnamese and majority Vietnamese in their sample. On the Comprehensive Test of Basic Skills the majority Vietnamese had a slightly higher AQ (99.5, N=54) than the Chinese-Vietnamese (97.8, N=45).

■ Vietnamese Australians

More than 200,000 people of Vietnamese descent live in Australia, and there is a small amount of cognitive data available for this population.

Dandy & Nettelbeck (2002 ) administered the Standard Progressive Matrices to a lower SES group of 56 Vietnamese children in grades 6 and 7. A matched sample of lower SES whites, and a higher SES sample of Chinese Australians were included as comparison groups. SPM scores are not reported, but there was no difference between the Vietnamese and white Australians (according to the authors anyway … I hate it when numbers are not reported).

This does not imply an IQ of 100 (cf. Lynn, 2008, pp. 50-51); the white comparison group was selected on the basis of low SES, and it is likely that their scores would be below the “Greenwich Standard” UK test norms.

Another study provides Advanced Progressive Matrices scores for some students and recent graduates of the University of New South Wales (Nguyen-Hoan, 2008 ). 38 bilingual Vietnamese were compared with 55 monolingual English-speaking students. The IQ of the Vietnamese students was 110.8 and the IQ of the native students was 111.6. Vietnamese students were selected for strict English-Vietnamese bilingualism, so no one in this sample was from a Chinese-speaking family.

Table V: IQ test scores for Vietnamese Australians

Admin Sample Age N Test IQ Reference
2007 MA 20 38 APM 111 Nguyen-Hoan, 2008


Levels et al (2006 ) provide immigrant scores from PISA 2003 for ethnic groups all over the world. The Achievement Quotient for 126 Vietnamese Australians was 109.2.

According to the 2001 census, 40.3% of Australians that were born in Vietnam are ethnic Chinese (Ember & Skoggard, 2005, p. 1147). It would be good to know if the Chinese-Vietnamese in Australia have different abilities than majority Vietnamese, but the lack of a difference in America makes this concern seem a lot less relevant.

The study by Dandy & Nettelbeck (2002) might suggest a somewhat below average IQ for Vietnamese Australians because they scored like a disadvantaged group of whites. But Nguyen-Hoan (2008) finds no real gap for an elite sample, which perhaps implies no gap at all. Neither one of these studies is ideal.

PISA is the best sample and indicates a very high level of achievement, if not intelligence.

Table VI: Achievement scores for Vietnamese Australians

Admin Sample Age N Test AQ Reference
2003 A 15 126 PISA 109 Levels et al, 2006


The intelligence of transracially adopted Vietnamese

There is a modest but growing literature showing that Koreans adopted by white families in Europe and North America develop higher IQ and academic ability than white adoptees or the general population. These studies suggest that the high cognitive scores generated by South Korea and Korean immigrants to the West are not due to cultural transmission, but are the result of hereditary differences.

Some data for Chinese adoptees has entered the literature and suggests a similar pattern.

More commonly, researchers do not look for or report differences across ethnic, regional, or racial groups when they publish psychological data for samples of intercountry adoptees. Adoptees from many different regions are often lumped together, even when the sample sizes can comfortably accommodate disaggregation.

Transracial adoption studies could add some real insight into the mystery of Southeast Asian intellectual potential.

The abstract of one small study, which I mentioned above, promises data for “25… subjects … adopted from Southeast Asia” (Clark & Hanisee, 1982 ). Annoyingly, the authors consider Korea a part of Southeast Asia: the sample consists of 12 children from Vietnam, 8 from Korea, 3 from Cambodia, and 2 from Thailand. So the sample is about 68% Southeast Asian and 48% Vietnamese.

These children had an IQ of 114.9, suggesting no deficit for the Southeast Asians. Richard Lynn simply re-classifies the Vietnamese as Chinese by fiat and uses the study as evidence that ‘East Asians’—instead of ‘Southeast Asians’—have genetically high IQ (Lynn, 2006, pp. 139-140). His section on Southeast Asians only presents evidence for genetically lower IQs.

I have located another transracial adoption study that has been completely overlooked by hereditarian researchers, perhaps due to the bias I just illustrated.

McBogg & Wouri (1979 ) report data for 36 Vietnamese children adopted into white American homes. 100% of the children had histories of malnutrition, disease, and deprivation prior to adoption. The average age of the children at assessment was about 4 years old, and they had been placed in their home at an average age of 2. 70% were placed before their first birthday.

The adoptees were all evaluated with the Slosson Intelligence Test and their average IQ was 110.9!

An overlooked issue with the Vietnamese adoption samples from both of the studies reviewed above is not that they are Chinese, but that their origin in the 1975 wave of refugees does suggest that they could be from more elite families. That means an advantaged genetic background compared with the average Vietnamese. Assuming that Vietnam’s IQ is 91.4, this implies that the average IQ of the biological parents of McBogg & Wouri’s sample was 114. This is not an implausibly high IQ for VIPs in the South Vietnamese establishment.

On the other hand, the first wave of refugees was far from uniformly elite, and the origin of the adoptees is reported as a complete unknown: they came to America as sick and starved foundlings. There is no real reason to believe these were the abandoned or orphaned children of generals and politicians, although this possibility also can’t be dismissed.

Table VII: IQ scores of transracially adopted Vietnamese

Admin Sample Age N Test IQ Reference
1978 MD 1-11 36 Slosson 111 McBogg & Wouri, 1979



■ The average IQ of Vietnam from six normal samples is 91.4. But there is some evidence that IQ in Vietnam increases to about 100 during adolescence.

■ Recent PISA results indicate that Vietnam has an Achievement Quotient of 102. Although some skepticism over this result seems warranted.

■ There is a .33 correlation between latitude and test scores in Vietnam: the Northern part of the country has slightly higher scores than the Southern part.

■ The average IQ for Vietnamese Americans from six normal samples is 100.7.

■ The average AQ for Vietnamese Americans from four normal samples is 100.6.

■ The achievement test performance of Vietnamese Americans has increased over time since the 1980s, and this trend is ongoing.

■ Chinese-Vietnamese Americans do not have higher test scores than majority Vietnamese; their presence in the U.S. does not account for the high performance of Vietnamese Americans.

■ Vietnamese Australians excelled at PISA, but two studies offer a murky picture of IQ: it appears to be average to somewhat below average.

■ One sample of transracially adopted Vietnamese children suggests a high level of intellectual potential for this population. Another partial sample of Vietnamese adoptees suggests the same. Both samples came to America on a wave of elite immigration, which could imply that they were from above average backgrounds. The origin of these infants is unknown, but their sorry condition upon arrival did not denote privilege.



⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻ REFERENCES ⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻

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Chua, A. (2003). World on Fire: How exporting free-market democracy breeds ethnic hatred and global instability. New York, USA: Doubleday.

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Ember, M., & Skoggard, I. (Eds.). (2005). Encyclopedia of Diasporas: Immigrant and Refugee Cultures Around the World.Volume II: Diaspora Communities. Springer.

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  1. JayMan

    Very interesting look at this area. Southeast Asia in general is a place where much more research is needed.

    I have long suspected a north-south gradient in average IQ in Vietnam. While there appears to be one, it is much more muted than I expected (assuming these data are representative).

    If I were to guess, I’d suspect the average genotypic IQ of Vietnam was around 95. But, we’ll see.

  2. Dan

    I’m curious as to why Lynn is so deficient in these smaller nations (Not Vietnam specifically, but a lot of the Caribbean nations you went over).

    Are you privy to studies he had no knowledge of, or was he just lazy when it came to these “lesser” nations.

    • Jason Malloy

      Smaller nations are probably harder to find data for, and they are less important.

  3. durrr

    The average IQ is dragged down by samples from the 5 and 8 year olds. What would the average IQ have been if those samples were not included? Also is there as big a gap in other countries between the test results of 5 and 8 year olds compared with 12 and 15 year olds?

  4. Jamison

    Lynn’s treatment of Vietnamese IQ is pretty much embarrassing. The work you’ve done here really outclasses much of his.

    • Steve Sailer

      The funniest thing is how Jason does prodigious amounts of work and then arrives at averages for Southeast Asian countries that aren’t too far off from Dr. L.’s scientific wild-ass guesses.

      • Jamison

        In some cases, that appears to be the situation, but if guess work is Lynn’s main method of gauging average IQ’s, then his work doesn’t warrant being considered academic. What struck me about Vietnam was Lynn’s shoddy, largely baseless treatment of vietnamese immigrant and how chinese-vietnamese account for the national average and the performance of immigrant populations. From this, it’s clear that the genotypic IQ of ethnic vietnamese is much higher than what he’s argued, and their genotypic IQ is quite likely 100, which has also long been my impression.

      • trinhconanh

        Décidément ,vous avez une dent contre les vietnamiens ! lol . Cela montre plutot qu’il y a une grande différence et que le travail de Lynn est vraiment brouillon et de piètre qualité !

  5. Steve Sailer


    I read a stock advice book a few years ago by the head guy for developing markets at Morgan. He implied that a lot of investors had been burned on investing in Vietnam. They had reasoned that the place is full of clever people, so it will become as prosperous as China. But so far that hasn’t worked out. He attributes that to the geography — unlike China, most of Vietnam has a very short coastal shelf accessible by river transport before you get to the mountains. It’s kind of like the U.S., only more so, where the East Coast had only so much land, and it wasn’t until the Great Lakes and Mississippi Basin were settled that economic growth became fairly easy.

    • Nhan Nguyen

      One should also take into the historical context of a nation’s economic development. Unlike China which was opened up to the West in 1972 when their economic development began to take hold, Vietnam was mired in a detracted war with America until 1975. Then more wars followed with Cambodia and China until the early 1990’s. The West also placed a trade embargo against Vietnam which was not lifted until the the late 1990’s. Vietnam is roughly about 25 years behind China in terms of economic development. If one looks at the GDP of China 25 years after it opend its market to the West, Vietnam may be a about the same GDP. Time will tell where it will be in another 25 years if war does not return to that nation.

      • Viet

        One should also take into account the communist government. Corruption abounds under such a system. Government positions are given to the inept and incompetent it is no wonder the country is the way it is. Talented and competent people are not wanted in government as it may threaten their hold on power. Being in government in VN is like being in a candy shop for the politicians. I heard some $160 billion was frozen by the US which was siphoned by VN polies into US bank accounts.

  6. David

    Hi Jason, were the PPVT’s in Table 3 done in English? I don’t believe PPVT scores are good for analyzing immigrant IQ scores, since most young immigrants are bilingual and usually are not proficient in both English and their native language.

  7. Angela

    There is no way the vietnamese IQ is that high. The reason Vietnamese have slightly higher IQs than most south east asians at that latitude is due to China admixture (North Vietnam was part of China for 1000 years). And whilst this does mean that the disparity between north and south should be even greater than the one in Japan and Korea, vietnam should still have significantly lower IQs than the Chinese.

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