Innovators Who Immigrate
Like the rest of New Things Under the Sun, this article will be updated as the state of the academic literature evolves; you can read the latest version here.
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Talent is spread equally over the planet, but opportunity is not. Today I want to look at some papers that try to quantify the costs to science and innovation from barriers to immigration. Specifically, let’s look at a set of papers on what happens to individuals with the potential to innovate when they immigrate versus when they do not. (See my post Importing Knowledge for some discussion on the impact of immigration on native scientists and inventors)
All of these papers confront the same fundamental challenge: successfully immigrating is (usually) a matter of choice, selection, and luck. For the purposes of investigating the impact of immigration on innovation, that means we can’t simply compare immigrants to non-immigrants. For example, immigrants (usually) choose to migrate, and if they do so because they believe they will be more successful abroad, that signals something about their underlying level of ambition and risk tolerance. That, in turn, might mean they are more likely to be innovative scientists or inventors, even if they had not migrated. Compounding this problem, countries impose all sorts of rules about who is allowed to migrate and many of these rules make it easier to migrate if you can demonstrate some kind of aptitude and talent. That means successful immigrants are often going to be drawn from a pool of people more likely to have the talent to succeed in science and invention, even if they had not immigrated.
These are challenges; but there is also a degree of capricious luck in immigration (and life in general). There are people - perhaps many people - who want to immigrate and have extraordinary talent, but who do not for all sorts of random reasons. Compared to otherwise identical people who do migrate, they might lack information, financial resources, or face higher barriers to legal immigration. Indeed, in many cases, immigration is literally handed out by lottery! The papers we’ll look at employ various strategies to try and find comparable groups of people who immigrate and people who do not, to infer the impact of immigration and place on innovation.
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Talented High Schoolers
One way to deal with the selection effect is to try and measure the talent of a sample of both immigrants and non-immigrants and then compare immigrants and non-immigrants who appear to have similar underlying talent. Agrawal and Gaule (2020) and Agrawal et al. (2023) does this with the International Mathematical Olympiads.
The International Mathematical Olympiads is a prominent math competition for high school students from around the world that’s been held annually for decades. Up to six representatives from each country are selected via regional and national competitions, and then travel to a common city and try to solve six different (presumably very hard) math problems. Because it’s an Olympiad, winners take home gold, silver and bronze medals. Agrawal and coauthors know the scores of all the competitors from 1981 to 2000 and then look to see what happens to the competitors later in life. In Agrawal and Gaule (2020) they show that scores on these math competitions strongly predicts later success as a mathematician. That in itself is surprising, given that the talents for doing creative mathematical research may, in principle, differ substantially from performance in a competition.
From Agrawal and Gaule (2020)
Their dataset also establishes something else: students from low income countries are less likely to obtain PhDs in math than students with the same score from high-income countries. In Agrawal et al. (2023) they use this dataset to look at the different fates of those who immigrate from their home country and those who do not. On average, a migrant is about twice as likely to be employed in academia as a mathematician as someone from the same county who got the same math score but did not migrate.
Of course, while math scores help address the problem of selection, this doesn’t really get at the problem of choice. Perhaps people who really want to be mathematicians are disproportionately likely to migrate, since the highest ranked mathematics departments tend to be in the USA, and it’s this difference in career intention that explains the difference in career outcomes between migrants and non-migrants.
Agrawal et al. (2023) provides some additional evidence that this is not purely an outcome of career choice. For one, looking only at migrant and non-migrant students who both become math academics (in their own country or abroad), they find the migrants go on to garner about 85% more citations to their publications than their domestic peers (remember, with the same score in math competitions). We might think citations aren’t a great measure of math skill (see my post Do Academic Citations Measures the Value of Ideas?), but they also show migrant academics are about 70% more likely to become speakers at the International Congress of Mathematicians (a non-citation-based measure of community recognition). So among people who ended up becoming academic mathematicians (either at home or abroad), the ones who migrated went on to have more distinguished careers, as compared to their peers who did equally well in high school on math.
But this is still pretty indirect evidence. Fortunately, Agrawal and coauthors also just asked Olympiad medalists directly about their preferences in a survey. From respondents in low- and middle-income countries, 66% said they would have liked to do their undergraduate degree in the USA if they could have studied anywhere. Only 25% actually did. Just 11% said their first choice was to study in their home country. In fact, 51% did.
Why didn’t they study abroad if that’s what they wanted to do? A bunch of the survey evidence suggests the problem was money. For 56% of the low- and middle-income respondents, they said the availability of financial assistance was very or extremely important. Students from low- and middle-income countries were also much more likely to choose a hypothetical funded offer of admission at a lower ranked school than their peers in high-income countries.
Gibson and McKenzie (2014) provides some complementary evidence outside of mathematics. As part of a larger project on migration and brain drain, they identify 851 promising young New Zealanders who graduated high school between 1976 and 2004. These students either represented New Zealand on the International Mathematical Olympiad teams, the International Chemistry Olympiad team, were top in exams, or earned the New Zealand equivalent of the valedictorian rank. Like Agrawal and coauthors, they can then see what happens to New Zealanders who migrate, versus those who remain. They find researchers who moved abroad publish more than those who do not.
As noted, this poses some potential problems; even though we know all these students were talented, those who migrate may have different unobserved levels of skill, ambition, risk tolerance, or something. One way they attempt to deal with this is to focus their attention on the subset of researchers who actually do migrate away from New Zealand, and then looking to see what happens to their research output when they move back. The idea here is those who left were, at least initially, displaying similar levels of skill, ambition, risk tolerance, and so forth (if so, why did they return? We’ll get to that).
For each New Zealand migrant researcher who returns to New Zealand, Gibson and McKenzie try to find another migrant who stayed abroad, but is similar in age, gender, what they studied in high school, highest degree, and so on. They then look to see what happens to the number of citations to their academic work. While both groups had essentially the same citations prior to return migration, after one group returned to New Zealand, the citations to their work declined substantially relative to the citations of migrants who remained abroad.
From Gibson and McKenzie (2014).Citations fall at the end partially due to a mechanical effect: there are fewer years available for more recent papers to receive citations.
Again, we see that being abroad was good for research productivity. But again, perhaps we are concerned that there is an important but unstated difference between New Zealanders who stayed abroad and those who returned home. Perhaps the ones who came back simply couldn’t cut it?
But we actually don’t see much evidence of that. The figure above matches each returnee to someone who stayed abroad based on a number of characteristics. But one characteristic they were not matched on is citations to their academic work. And yet, prior to returning, their citations were on a very similar trajectory. And like Agrawal and coauthors, Gibson and McKenzie also surveyed their subjects to see why they moved back. Most of the answers were not related to individual research productivity, but had to do with, for example, concerns about aging parents, child-raising, and the location of extended family.
Scholarship Restrictions
Another line of evidence comes from Kahn and MacGarvie (2016), which focuses on PhD students who come to America from abroad. The paper’s big idea is to compare students who come on the prestigious Fulbright program to similar peers who were not Fulbright fellows. The students and their matches are really similar in this case: they graduated from the same PhD program, either studying under the exact same advisor and graduating within 3 years of each other, or merely studying in the same program but graduating in the same year. The only difference was the Fulbright students have a requirement to leave the USA for two years after finishing their studies, whereas the matched students faced no such...