The Scale and Selectivity of Foreign-Born PhD Recipients in the US

Jeffrey Grogger, University of Chicago and NBER
Gordon Hanson, UC San Diego and NBER (*)
January 2013

Abstract. In this paper we study the scale and selectivity of foreign-born PhD students in science andengineering. We focus on students from China, India, Korea, and Taiwan, which together account formost roughly one-third of S&E PhD students in the US. The selectivity of these students is high, asmeasured by their fathers’ relative education levels. In China and India, fathers of students who receive
US S&E PhD’s are roughly 15 times more likely to have a BA degree than their contemporaries are tohave tertiary education. Over time, selectivity falls for China but the trend for other countries isambiguous.

I. Introduction
The scale, skills, and selectivity of migrants are among the most economically importantcharacteristics of immigration flows (George Borjas 1987; Jeffrey Grogger and Gordon Hanson 2011).
In a standard economic model, they influence relative wages, the distribution of income, and the size ofthe immigration surplus enjoyed by natives (Borjas 1995, 2009). In this paper we consider the scale andselectivity of a small but skilled segment of immigrants to the United States: students who come to theUS to obtain PhDs in science and engineering (S&E).
S&E PhDs are essential inputs in the production of knowledge and are eagerly recruited bycompanies as well as countries (Devesh Kapur and John McHale, 2005). Science and engineering
graduates produce patents at much higher rates than graduates in other fields (Jennifer Hunt andGauthier-Loiselle, 2010), and top S&E scientists are relatively likely to launch high-tech companies________* The authors acknowledge helpful comments from William Kerr, Paul Oyer, Giovanni Peri, and SarahTurner. Authors: Jeffrey Grogger, University of Chicago, 1155 E. 60th Street, Chicago, IL, 60637, (773)542-3533, jgrogger@uchicago.edu; Gordon Hanson (corresponding author), UC San Diego, 9500
Gilman Drive 0519, La Jolla, CA, 92093-0519, (858) 822-5087, gohanson@ucsd.edu.
Session Title: High Skill Immigration in the U.S., Sarah Turner (session chair), Giovanni Peri, PaulOyer, (discussants).

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(Lynn Zucker and Michael Darby 2009).1 Attracting S&E graduates thereby enhances a country’s
potential for economic growth (Charles Jones, 1995a,b).
Although some foreign-born PhDs return to their country of origin upon completing theirdegrees, most remain in the United States, at least to start their careers. Michael Finn (2010) estimatesthat for the 2005 cohort of US PhDs, 67% of foreign-born doctorates were working in the United States
two years after graduation. Two-year stay rates were highest for S&E graduates, especially in computerand electrical engineering (77%), computer science (75%), physical science (75%), life science (75%),
and mathematics (73%). Foreign–born students who obtain their PhDs in the US thus contribute
importantly to the stock of US human capital.
In this paper we study the scale and selectivity of foreign-born PhD students in S&E fields. We
focus on students from four countries: China, India, Korea, and Taiwan. As we show below, students
from these four countries account for the lion’s share of foreign-born S&E PhD students in the US.
We analyze data from the National Science Foundation’s Survey of Earned Doctorates, whichprovides a census of all students completing PhDs in the United States since 1960. We focus on S&E
PhDs over the most recent 20 years, during which time the scale of immigration has changed
considerably. We also analyze changes in one measure of selectivity over time, namely, the share of
PhD students whose parents hold bachelor’s degrees.
Presumably, the more positively selected are foreign-born PhDs in terms of ability, the more
likely they are to contribute to the production of knowledge in the United States. One might expectselectivity to fall as the number of foreign PhD students increases. At the same time, increasing
education levels in the home country could lead to rising shares of immigrant PhD students whoseparents themselves are college educated.
Recent US policy toward foreign students could also influence the selectivity of entering PhD
students from abroad. After September 11, 2001, the US imposed restrictions on student visas that
substantially reduced the share of students studying abroad who came to the United States (John Bound,Susan Turner, and Walsh, 2009). Whether these restrictions should have raised or lowered the selectivityof US-bound students is not clear. If visa requirements targeted students’ educational backgrounds,selectivity may have risen. If the most qualified students faced the highest opportunity cost ofcomplying with new application conditions, then they may have studied elsewhere instead, reducing theselectivity of US-bound students.
In the next section of the paper, we discuss the SED data in more detail. We then present anddiscuss our empirical findings.
II. Data
The Survey of Earned Doctorates covers all individuals receiving a PhD from an accredited US
institution from 1958 forward. We have complete data through 2007. We focus on data from 1987 and2007, a 20-year horizon over which the salient trends in the data are apparent . Considering that the1In other related work, Hunt (2011) finds that immigrants entering the US on student or temporary works visas
are much more likely to produce patents than individuals entering the country on a green card (the majority ofwhom would have obtained a permanent visa through having relatives in the United States).

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average time-to-degree for PhD students is about six to seven years, depending on the field, 2007 is
about the first year in which the effects of post-9/11 visa restrictions could appear in the data. We focus
the analysis on graduates in science and engineering fields, for which the link to innovative activity isstrongest. We restrict attention to China, India, Korea, and Taiwan. These are the largest sending
countries for PhDs and provide variation in terms of recent trends.
The SED provides great detail about each PhD graduate’s course of study and educational
background. At the same time, it provides rather limited information that is useful for assessing
selectivity. It does not provide GRE or TOEFL scores, for example.
The SED does provide data on the student’s parents’ educational attainment. From thisinformation we construct an indicator equal to one if the student’s father holds a bachelor’s degree orhigher and equal to zero otherwise. The SED also provides information about the mother’s educational
level, but the father’s level of education is generally greater and more predictive of the student’s postgraduation plans, so we focus on it.
Parents’ education captures only some of the sources of ability differences between PhD
recipients. At the same time, it likely captures differences that matter. Studies have generally shown apositive link between a worker’s earnings and the schooling of his parents, even after holding otherworker characteristics constant (David Lam and Robert Schoeni 1993; Lorraine Dearden 1999).
To account for education trends in home-country education levels, we also compute the share of
the father’s age cohort in the home country with any tertiary education. To do this we merge the BarroLee education data to the SED by country and time period, assuming that a student’s parents are 25
years older than the student.
III. Findings
Table 1 reports the number of individuals who received S&E PhD’s from US universities in1987 and 2007. In 1987, China, India, Korea, and Taiwan accounted for 2,374 PhD’s, which was 43
percent of all S&E PhD’s awarded to international students and 18 percent of all S&E PhD’s awarded
that year.
In 2007, the number of S&E PhD’s awarded to Chinese, Indian, and Korean students expanded,
whereas the number awarded to Taiwanese students fell. In total, the four countries accounted for 33
percent of US S&E PhDs awarded in that year. The number of Korean students doubled; the number ofIndian students nearly quadrupled. Growth in PhD’s awarded to Chinese students was explosive: intwenty years, the number increased by almost a factor of nine. By way of contrast, the number of S&E
PhD’s awarded to US students rose about 20 percent.
Table 2 presents our selectivity measure. The first row of the table shows the percentage of PhD
recipients whose fathers held BA degrees. Taiwan is the lowest, at 39 percent, and India the highest, at64 percent, with China and Korea at 48 percent. These numbers are all roughly comparable to the 53
percent of American PhD recipients whose fathers held bachelor’s degrees.
What’s striking about these numbers is how selective foreign PhD recipients are relative to theircompatriots. In China, about 1 percent of the recipients’ fathers’ age cohort had any tertiary education,compared to the 48 percent of recipients’ fathers who held a BA. In India, where 64 percent of recipients’3fathers had a bachelor’s degree, only 2 percent of the fathers’ age cohort had any tertiary schooling. In
the emerging economies of Korea and Taiwan, the selectivity of PhD students was not quite as high, but
still their fathers were about 10 times as likely to hold a BA as their fathers’ age cohort was to be tertiary
educated.
By 2007, paternal education of PhD recipients rose in most of the sending countries as well as
the US. This may partly reflect rising education levels at home, as observed in the last row of the table.
India, Korea and Taiwan provide mixed evidence on the link between the scale and selectivity of PhD
migrants. The number of Indians and Koreans receiving S&E PhD’s in the US rose substantiallybetween 1987 and 2007, as did the percentage of their fathers who held a BA degree. At the same time,
the share of Taiwanese students’ fathers who held BA degrees rose, even though their numbers droppedoff.
Because of the general increase in home-country schooling, it is hard to say whether PhD
students from India, Korea, and Taiwan became more or less selective over time. By an absolutemeasure, they became more selective. By a relative measure, they became less selective.
There is no ambiguity regarding China. Paternal education levels among Chinese PhD recipientsfell between 1987 and 2007, even though home-country education levels were rising. This suggests thatlarge increases in the scale of migration may lead to reductions in selectivity.

IV. Conclusions
Between 1987 and 2007, the number of S&E PhDs awarded by US universities rose by 68
percent. Much of this growth was due to growth among the largest sending countries, China, India, andKorea. PhD’s awarded to Chinese students grew explosively over this period, from 460 in 1987 to 4,029
in 2007. PhD’s awarded to American students grew by just over 20 percent.
The selectivity of these students is quite high, as measured by their fathers’ education level inrelation to that of their fellow citizens. In the low-income countries of China and India, the fathers ofstudents who receive S&E PhD’s in the United States are roughly 15 times more likely to have a BA
degree than their contemporaries are to have tertiary education. In the middle-income countries of Korea
and Taiwan, the ratio is lower, at about 4, which is nevertheless considerably higher than it is among
American PhD recipients, for whom it is about 1.2.
Because of general increases in home-country education, it is ambiguous whether recent PhD
graduates are more selective than those of 20 years ago. The exception is China, where selectivity
unambiguously fell. This raises the question of whether reductions in selectivity are the inevitable resultof explosive growth in the number of students receiving PhDs. Before drawing conclusions, though, itwould be useful to analyze other measures of selectivity that capture different aspects of skill.
References
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Table 1
Number of US S&E PhD's granted by year and recipient's country of origin
Year/Countryof origin
19872007

China
460
4,029

India
529
1,937

Korea
544
1,042

Taiwan841
522

Other intl.
3,129
5,551

US
7,974
9,613

Table 2
Education level of US PhD recipients' fathers and recipients' fathers' cohort, by country and year
Year/Countryof origin

Measure

China

India

Korea

TaiwanUS

Percentage ofrecipients' fatherswith BA's

48.3

64.1

48.0

38.8

52.5

Percentage ofrecipients' fathers'cohort with tertiary
education

0.9

1.8

4.0

5.1

31.0

Percentage of2007 recipients' fatherswith BA's44.8

83.5

59.3

61.5

68.6

Percentage ofrecipients' fathers'cohort with tertiary
education

2.9

4.9

13.7

16.3

55.8

1987

6

Total
13,477
22,694