Bryan Caplan  

The Wonder of International Adoption: High School Grades in Sweden

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Moving young children from the Third World to Sweden wipes out about half of their national IQ deficit.  What about performance in high school?  Vinnerljung et al.'s "School Performance at Age 16 Among International Adoptees" (International Social Work, 2010)  compiles the numbers, once again breaking them down by regular Swedes, Korean adoptees, and non-Korean adoptees.  Since these are high school students rather than conscripts, the data include women, yielding a much larger sample.  But otherwise, the national origin of the adoptees is basically the same as in Dalen et al. (2008) and Odenstad et al. (2008).  India, Thailand, Chile, Sri Lanka, Colombia, Ethiopia, and Ecuador top the list.

To start, imagine growing up in Sweden had zero effect on high school performance.  How would the non-Korean adoptees do?  As discussed earlier, if the non-Koreans had average IQ for their home countries, their mean IQ would be 84.  On the international PISA tests of science, reading, and math, countries with IQs around 84 score about one standard deviation below Sweden.*

When you look at adoptees' actual grades, however, the performance gap is much smaller.  Combining males and females, non-Koreans have an average GPA of 2.95, versus 3.24 for regular Swedes.  It's not in the paper, but Vinnerljung emailed me the standard deviation: .78.  That's a performance gap of only .37 SDs - over 60% less than you would expect from the PISA scores.  The gap is even smaller for non-Koreans who were adopted as infants.  And as I emphasized in my previous post, we should expect the international adoptees to be below average for their home countries, so the grade gain of growing up Swedish is probably even greater than it looks. 

What about the Korean adoptees?  They once again do better than regular Swedes, with an average GPA of 3.42.**  That's an edge of .24 SDs - almost exactly the PISA gap between Sweden and Korea.

For grades, like IQ, there are two stories to weave.  The pessimist can say, "Even in Sweden, non-Koreans' performance in school is well below average."  The optimist can say, "Non-Koreans in Sweden do much better than they would have done back home."  While both stories are correct, the latter is far more insightful.  The fact that non-Koreans underperform in Swedish schools is obvious at a glance.  The fact that non-Koreans excel compared to the relevant counter-factual, in contrast, is easy to miss.  Wherever you're from, Sweden is a good place to learn.

* The PISA gap is roughly 100 points, and scores are normed to have a standard deviation of 100.

** This slightly overstates Korean performance, because the Korean adoptees are over two-thirds female, and girls in all groups have higher GPAs than boys.  If you separately compare genders, Korean boys are .18 SDs and Korean girls are .18 SDs above the mixed-gender Swedish average.

COMMENTS (5 to date)
Colin Barnard writes:

Hey Brian,

Would you expect the fact of adoption itself to have any effect?

I noticed the paper had siblings of adoptees but didn't control for swedish born adoptees. If the swedish born adoptees had lower scores than regular swedes, that would make the international adoptees gains look even better.

Phil writes:

PISA and GPA are not the same thing. By basic statistics, if the correlation between IQ and GPA were .37, that would indicate NO effect of adoption.

If the correlation between PISA and GPA is, say, .74, then adoption closes exactly half the gap.

Phil writes:

BTW, it's hard for me to believe that students with an average IQ of 80 could have GPAs as high as 2.95. But that's my gut. I really have no idea.

Hazel Meade writes:

I think it's pretty clear that first world adoption of young children from the third world closes IQ gaps, because those kids get much better nutrition (among other environmental influences) during the first years of life. It might close all of it if prenatal nutrition in the third world reached first world standards, or it might not. But it's hard to claim definitively that there are inherent differences in intelligence given that closing nutritional deficits makes up for a large percentage of the gap. Everyone knows that fetal brain development, and thus intelligence, is impacted by environmental factors like alcohol and malnutrition. These studies show that you can explain at least half of the gap with environmental factors that occur after birth.

I'm tempted to suggest that the difference in IQ between Koreans and Swedes could be explained by what Koreans tend to feed their babies and what pregnant Korean women tend to eat. Lots more seafood maybe?

D Carroll writes:

It is well documented that both trauma and lack of nutrition in early childhood or prenatally, not to mention prenatal exposure to alcohol, negatively impact learning and behavior. In the context of third world orphanages, trauma typically means neglect or abandonment, though malnutrition also is traumatic. Early childhood and prenatal trauma changes the brain chemistry and the path of brain development. It can be addressed, though severe cases are very difficult. The older the child the harder it is. Adoption itself is also traumatic, though if ethical is an act that remediates more severe circumstances.

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