THE SELECTION OF HIGH-SKILLED EMIGRANTS
Matthias Parey, Jens Ruhose, Fabian Waldinger, and Nicolai Netz*
Abstract—We measure selection among high-skilled emigrants from Ger-
many using predicted earnings. Migrants to less equal countries are
positively selected relative to nonmigrants, while migrants to more equal
countries are negatively selected, consistent with the prediction in Borjas
(1987). Positive selection to less equal countries reflects university qual-
ity and grades, and negative selection to more equal countries reflects
university subject and gender. Migrants to the United States are highly
positively selected and concentrated in STEM fields. Our results highlight
the relevance of the Borjas model for high-skilled individuals when credit
constraints and other migration barriers are unlikely to be binding.
I.
Introducción
I NTERNATIONAL migration of high-skilled individu-
als has risen dramatically in recent decades (Docquier
& Rapoport, 2012). Between 2000 y 2006, los unidos
States attracted 1.9 million and European OECD countries
attracted 2.2 million tertiary-educated migrants (Widmaier
& Dumont, 2011). In the year 2000, high-skilled migrants
represented about 11% of the tertiary-educated population
in OECD countries (Brücker et al., 2012). In the United
Estados, as of 2013, acerca de 19% of the working-age popula-
tion with a bachelor’s degree or higher were foreign born. En
certain fields such as science, tecnología, engineering, y
matemáticas (STEM), más que 30% were foreign born.1
Access to high-skilled individuals is central to firms’ suc-
cess and has become even more important in economies
where ideas drive technological progress (Chambers et al.,
1998). When the home-grown pool of high-skilled individu-
als is insufficient, the ability to attract high-skilled migrants
is crucial for improving the quality of a country’s workforce
and its innovative capacity. A deeper understanding of the
selection of high-skilled migrants is therefore important for
sending and receiving countries alike.
While migrant selection has been studied extensively since
Borjas (1987) outlined theoretical predictions for selec-
ción, few papers have studied the selection of high-skilled
migrants. Focusing our analysis on high-skilled migrants
who mostly migrate between developed countries enables
us to investigate a setting where individuals face low legal
Received for publication October 30, 2015. Revision accepted for
publication September 7, 2016. Editor: Amit K. Khandelwal.
* Parey: University of Essex and Institute for Fiscal Studies; Ruhose: Leib-
niz Universität Hannover; Waldinger: London School of Economics; Netz:
DZHW.
We thank the editor Amit Khandelwal and three anonymous referees for
very helpful comments. We also thank Clement de Chaisemartin, tomás
crossley, Christian Dustmann, Tim Hatton, Hans Hvide, Julian Johnsen,
Gordon Kemp, and participants in various seminars. We thank Kolja Briedis,
Christian Kerst, and Gregor Fabian for providing access to the DZHW data.
This study uses data from the Swiss Labour Force Survey (Schweizerische
Arbeitskräfteerhebung, BFS). M.P. gratefully acknowledges the support of
the ESRC Research Centre on Micro-Social Change at the University of
Essex.
A supplemental appendix is available online at http://www.mitpress
journals.org/doi/suppl/10.1162/REST_a_00687.
1 Authors’ calculations based on the 2013 ACS (Ruggles et al., 2010).
barriers to migration and relatively small migration costs.
The economic forces described by the Borjas model should
be particularly relevant in our setup.2
A basic version of the Borjas (1987, 1991) modelo, build-
ing on Roy (1951), predicts that migrants to less equal
countries, such as the United States, should be positively
selected, while migrants to more equal countries, como
Dinamarca, should be negatively selected. Analyzing migra-
tion to both less and more equal countries is therefore
particularly valuable to test the predictions of the model.
We study the selection of high-skilled emigrants by
investigating migration decisions of graduates from Ger-
man universities. Germany exhibits an intermediate level of
inequality for high-skilled individuals (figura 1). By study-
ing selection to less and more equal countries in the same
contexto, we can test both predictions of the Roy/Borjas
modelo. Además, we are able to test whether the pre-
dictions of the Roy/Borjas model hold within the population
of university graduates.3
We use rich survey data on German university gradu-
ates collected by the German Centre for Higher Education
Research and Science Studies (DZHW). German university-
bound students represent a more selective group than their
counterparts in most other economically developed coun-
intentos; this allows us to study migration patterns of the top
11% of the educational distribution.4
To measure selection, we compare predicted earnings of
migrants and nonmigrants. We first estimate an augmented
Mincer regression for graduates who work in Germany.
We then use the estimated returns to construct predicted
earnings independent of whether the graduate stays in Ger-
many or migrates abroad. Our data contain a rich set of
personal characteristics including family background, alto
school grades, university education (including the specific
university, sujeto, and grades), and information on mobility
before enrolling at university. These detailed characteristics
2 See section IIB for a review of empirical papers investigating migrant
selection across the entire skill distribution. The existing papers on migrant
selection mostly focus on low-skilled migration between Mexico and the
United States, where migrants face higher migration costs and legal barriers
to entry. Other papers on high-skilled migrants study other outcomes, semejante
as effects on the receiving economy (Hunt & Gauthier-Loiselle, 2010; Kerr
& Lincoln, 2010; Borjas & Doran, 2012; Moser, Voena, & Waldinger, 2014;
Kerr, Kerr, & Lincoln, 2015; Doran, Gelber, & Isen, 2014) and on source
countries (Docquier & Rapoport, 2012).
3 Since many papers investigate migrant selection between two countries
solo (see online appendix table A.1), they are limited to testing one of the
two predictions of the Roy/Borjas model. While Borjas, Comerciante, y
Poutvaara (2015) study migration from Denmark to multiple destinations,
they focus on positive selection because Denmark has very low levels of
inequality.
4 Administrative data show that about 11% of the cohorts we study in our
paper graduated from a university. En 2012, the stock of university graduates
entre 35- to 44-year-olds was 1,208,000 out of a population of 11,004,000
(DESTATIS, 2013).
La revista de economía y estadística., December 2017, 99(5): 776–792
© 2017 by the President and Fellows of Harvard College and the Massachusetts Institute of Technology. Publicado bajo una atribución Creative Commons 3.0
no portado (CC POR 3.0) licencia.
doi:10.1162/REST_a_00687
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THE SELECTION OF HIGH-SKILLED EMIGRANTS
777
Figure 1.—Earnings Inequality among the High Skilled: Ratio of 75th
to 25th Percentile in the Earnings Distribution of University Graduates
EE.UU
Francia
Poland
Italia
España
Japón
Canada
Reino Unido
Austria
Luxembourg
Suiza
Bélgica
Alemania
Irlanda
Suecia
Países Bajos
Australia
Norway
Finland
Dinamarca
1.2
1.4
1.6
1.8
2
75/25 ratio, university graduates
The figure shows the ratio of the 75th to the 25th percentile in the earnings distribution of university
graduates. Authors’ calculations based on country-specific earnings surveys (see online appendix table A.3),
showing averages over the period 1998 a 2010. Details on data sources and the construction of inequality
measures are reported in section IIIB and data appendix B.1.
allow us to obtain predicted earnings as a precise measure
of individual earnings potential, so that we can differentiate
between high- and low-productivity graduates. We then com-
pare cumulative distribution functions of predicted earnings
for three groups of graduates: graduates who stay in Ger-
muchos, graduates who migrate to less equal countries, y
graduates who migrate to more equal countries. This allows
us to investigate whether the most or least skilled univer-
sity graduates stay in Germany or select into more or into
less equal destinations. To classify destinations into either
more or less equal countries, we construct new inequality
measures for university graduates, based on individual-level
income surveys from twenty countries.
The selection of university graduates is consistent with
the predictions of the basic Roy/Borjas model. Migrants to
less equal countries have significantly higher predicted earn-
ings than nonmigrants. Migrants to more equal countries,
in contrast, have significantly lower predicted earnings than
nonmigrants. These findings hold along the whole distri-
bution of predicted earnings. De hecho, the selection patterns
predicted by the model hold even within subgroups of either
more equal or less equal countries.
The coefficients of the Mincer regression, which form the
basis of our earnings prediction, might be biased if migrants
were nonrandomly selected from the population of graduates
in a way not captured by our observed covariates. We address
potential selection in the augmented Mincer regression using
a sample selection correction (Heckman, 1979). In the selec-
tion equation we use the rollout of ERASMUS, the largest
study-abroad program, as an instrumental variable to pre-
dict whether individuals move abroad or work in Germany.
Changes in the number of ERASMUS places are a good pre-
dictor of international migration (Parey & Waldinger, 2011).
Using the selection-corrected Mincer regression, we confirm
our main results. We also show that our results are not
driven by our particular measure of earnings inequality or
potentially confounding factors that may be correlated with
cross-country inequality.
Además, we show that our results hold for migrants
to European countries. Migration costs to these countries
are low because workers can move freely between Euro-
pean countries without the need for work visas. In further
resultados, we show that migrants to Austria and Switzerland,
two countries with higher earnings inequality than Ger-
muchos, are positively selected, as predicted by the Roy/Borjas
modelo. These countries provide a useful setting to test for
migrant selection because migration costs are particularly
bajo: the two countries share a border with Germany, son
predominantly German speaking, and have broadly similar
labor market institutions, benefit systems, and cultures. Fur-
thermore, Germans do not need visas to work in Austria or
Suiza.
In additional results, we decompose predicted earnings to
identify the characteristics that explain the observed selec-
tion patterns. Migrants to less equal countries have better
university grades, attend better universities, and come from
families with higher socioeconomic backgrounds. Migrants
to more equal countries have studied subjects with lower
returns in the labor market, are more likely to be women,
and attend universities associated with lower labor market
prospects. Curiosamente, migrants to more equal destinations
are in fact positively selected in terms of university grades.
Selection patterns are thus consistent with the model predic-
tions for most, but not all, characteristics.5 Predicted earnings
provide a comprehensive summary measure of expected
productivity that drives migration decisions.
Finalmente, we investigate selection to the United States, uno
of the most important destinations of high-skilled emigrants
from Germany. En los Estados Unidos, earnings inequality
among university graduates is much higher than in Ger-
muchos. As predicted by the Roy/Borjas model, emigrants
from Germany to the United States are positively selected
compared to nonmigrants. We show that migrants to the
United States are positively selected across almost all char-
acteristics compared not only to nonmigrants in Germany but
also to U.S. natives. We also document that migrants from
Germany to the United States are particularly concentrated
in high-paying STEM fields.
En general, high-skilled individuals form an important group
of potential migrants because of both their relatively high
rates of mobility and their potential contribution to the host
economía. Studying migrant selection in this context is partic-
ularly useful because these migrants face low formal barriers
to migration and are unlikely to be credit constrained. El
observed selection patterns underline the relevance of the
Roy/Borjas model in this setting.
5 A multidimensional extension of the Roy/Borjas model indicates that
focusing on a single characteristic may not reflect the overall pattern of
selección, depending on the correlation with other relevant characteristics.
See Dustmann, Fadlon, and Weiss (2011) for a model with two types of
habilidades.
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778
THE REVIEW OF ECONOMICS AND STATISTICS
II. A Model of Migrant Selection and
Existing Empirical Evidence
A. Roy/Borjas Model of Migrant Selection
In his seminal work, Borjas (1987, 1991) proposes a
theoretical framework for understanding the selection of
international migrants. To motivate our empirical analy-
hermana, we use important insights of the Roy/Borjas model to
highlight the predictions for selection. In our context, univer-
sity graduates decide whether to migrate based on earnings
opportunities abroad (w1) and at home (w0), and migration
costos (C). In this framework, potential log earnings consist of
an observed component (θj, where j = 0 indicates home and
j = 1 indicates abroad) and an unobserved component ((cid:3)j):
log w0 = θ0 + (cid:3)0,
log w1 = θ1 + (cid:3)1.
(1)
(2)
Taking migration costs (C) into account, individuals will
move abroad if the wage gain is larger than the migration
costos:
Migrate = 1 if θ1 + (cid:3)1 > θ0 + (cid:3)0 + C.
(3)
, p2
(cid:3)0
, p2
(cid:3)1
, p2
θ1
The vector of potential outcomes is (θ0, θ1, (cid:3)0, (cid:3)1). Para
tractability, we assume that the outcome vector is jointly
normally distributed with means (μ0, μ1, 0, 0) and variances
(p2
). Mean earnings at home and abroad are
θ0
represented by μj, and the variance of the observed compo-
nent in each country is represented by σ2
. We allow each
θj
type of skill (observables and unobservables) to be correlated
across countries but not across types of skills. σθ0,θ1 is the
covariance in the observed component across countries. Nosotros
refer to the corresponding correlation as ρθ. While our frame-
work incorporates observed and unobserved skills, this does
not affect the underlying economic mechanism developed
by Borjas (1987, 1991).6
We now consider how earnings potential at home, θ0, de
migrants differs from the population mean μ0. Desde
normality assumption, we obtain
mi(θ0|Migrate=1)
(cid:2)
= mi(θ0|θ1 + (cid:3)1 > θ0 + (cid:3)0 + C)
σθ0
σθ1
σθ1
σθ0
σv
= μ0 +
ρθ −
(cid:3)
Fi(z)
1 − Φ(z)
(4)
(5)
,
where v = θ1+(cid:3)1−θ0−(cid:3)0 is the earnings difference between
abroad and home that has variance σ2
v. z = (μ0 + c − μ1)/σv
is a constant reflecting differences in means across destina-
ciones, adjusted for migration costs and normalized by the
(cid:5)
(cid:4)
σθ0/σθ1
variance of the earnings difference. In our empirical analy-
hermana, we investigate how selection on observables relates to
relative inequality
between the two destinations.7
In addition to relative inequality, the theoretical prediction
on selection depends on the cross-country correlation in the
observed component (ρθ). A situation where ρθ is sufficiently
high provides a natural benchmark case because we ana-
lyze migration flows between industrialized countries.8 If
the potential destination is less equal than home (σθ1 > σθ0),
migrants will be positively selected: mi(θ0|Migrate=1) > μ0.
Intuitivamente, the positively selected migrants benefit from the
upside opportunities in less equal countries. If the potential
destination country is more equal (σθ1 < σθ0), migrants will
be negatively selected: E(θ0|Migrate=1) < μ0. Intuitively,
the negatively selected migrants benefit from the insurance
of a compressed wage distribution in more equal countries.
The model emphasizes the role of earnings inequality
for the selection of migrants. Differences in mean earnings
between home and abroad have strong effects on migration
probabilities (see term z above), but they have no effect on
the direction of selection.
Borjas (1991) extends the model to include stochastic
migration costs, leading to very similar results as long as the
migration costs are unrelated to potential earnings; Chiquiar
and Hanson (2005) emphasize that selection patterns can
change substantially when migration costs vary systemati-
cally with earnings potential. Because we are focusing on
high-skilled individuals who migrate from an economically
developed country to other developed countries, differen-
tial migration costs are presumably less important than
for lower-skilled migrants who migrate from, for example,
Mexico to the United States.
B. Empirical Evidence on the Roy/Borjas Model
Most empirical papers on international migrant selection
study settings where migrants face legal barriers to migration
and migration costs are relatively high. Existing papers dif-
fer along two main dimensions that affect observed selection
patterns. First, different papers use different skill measures
to evaluate selection, and second, they study migration flows
between a varying set of countries (see online appendix
table A.1). A large part of the empirical literature has stud-
ied emigration from Mexico to the United States. While
some of these papers find evidence for negative selection
that is consistent with the basic Roy/Borjas model (e.g.,
Ibarraran & Lubotsky, 2007; Fernandez-Huertas Moraga,
2011; Kaestner & Malamud, 2014, for some characteristics),
other papers find intermediate selection that suggests that
migration costs vary with skills, perhaps driven by poverty
constraints (Chiquiar & Hanson, 2005; Orrenius & Zavodny,
2005; Kaestner & Malamud, 2014, for other characteristics).
6 Borjas (1987) develops the original model focusing on the role of
unobservables. In the formulation here, this corresponds to the case of
σθ0
= 0. Borjas (1991) introduces the distinction between returns
to observables and unobservables, focusing on the case where observable
skills are perfectly correlated across countries (corr(θ0, θ1) = 1).
= σθ1
7 Our data include a rich set of observable characteristics, which allows us
to construct an informative measure of skills. See Gould and Moav (2016)
for an analysis that investigates selection on unobservable skills.
8 This rules out the case of “refugee sorting” (Borjas, 1987).
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THE SELECTION OF HIGH-SKILLED EMIGRANTS
779
In their seminal paper, Chiquiar and Hanson (2005) show
that a model with skill-varying migration costs provides a
better description of migration flows from Mexico to the
United States.
A number of other papers investigate migrant selec-
tion between other pairs of countries. The selection of
migrants from Puerto Rico to the United States is consis-
tent with the model predictions (Ramos, 1992; Borjas, 2008).
Migrant selection from either Norway or Israel to the United
States is only partly consistent with the model predictions
(Abramitzky, Boustan, & Eriksson, 2012; Gould & Moav,
2016).
Finally, a number of papers investigate migrant selection
between multiple countries. Some papers find support for the
model predictions (e.g., Borjas, 1987; Borjas et al., 2015;
Stolz & Baten, 2012), while other cross-country studies find
only partial support for the basic Roy/Borjas model (Belot
& Hatton, 2012) or reject the model predictions (Feliciano,
2005; Grogger & Hanson, 2011).9
We are not aware of other papers that focus on the role of
inequality for the selection of high-skilled migrants.10 Study-
ing these migrants is particularly useful because they face
low legal barriers to migration and relatively small migration
costs.
III. Data
A. Data on University Graduates
We analyze the selection of high-skilled migrants using
survey data on university graduates collected by the Ger-
man Centre for Higher Education Research and Science
Studies (DZHW). These data come from nationally represen-
tative longitudinal surveys of individuals who complete their
university education in Germany (for details, see Grotheer
et al., 2012). The DZHW sampled university graduates from
the graduation cohorts 1992–93, 1996–97, 2000–2001, and
2004–2005.11 We refer to the cohorts by the second year
(e.g., 1993 for the 1992–93 cohort). Graduates in each
cohort are surveyed twice. The initial survey takes place
about twelve months after graduation. The same individu-
als participate in a follow-up survey about five years after
graduation (online appendix figure A.1). The survey is ideal
for our purposes because graduates are surveyed even if they
move abroad. We focus our analysis on migration decisions
that are measured five years after graduation.12 The surveys
are based on a stratified cluster sampling, with fields of
study, degree types, and universities as strata (Grotheer et
al., 2012), and they are representative for the examined pop-
ulation. Response rates to the initial surveys range between
30% and 40%, depending on the cohort. We analyze differ-
ences in response rates between the initial survey and the
follow-up survey according to migration status reported in
the initial survey. The follow-up survey response rate is 66%
for graduates who have worked in Germany during the ini-
tial survey and 59% for graduates who have worked abroad.
While this difference is statistically significant in a simple
t-test, we cannot reject that differences in response rates are
uncorrelated to observable characteristics. This suggests that
attrition does not change our findings. We also verify that our
results hold when we include the full sample from the initial
survey by carrying forward the reponses from the initial sur-
vey (see online appendix A.3 for details; results are shown in
online appendix figure A.3 and online appendix table A.6).
Five years after graduation, the total number of respon-
dents is 6,737 (1993 cohort), 6,237 (1997 cohort), 5,426
(2001 cohort), and 6,459 (2005 cohort). We focus on gradu-
ates from traditional universities.13 We restrict the sample to
full-time workers because migrating part-time workers are
more likely to be tied movers, that is, individuals follow-
ing a migrating partner (see Borjas & Bronars, 1991; Junge,
Munk, & Poutvaara, 2014). In our data, full-time labor force
participation is about 77%.
The graduate survey data contain detailed information
on graduates’ personal characteristics, family background,
study history, and labor market experience (table 1). In addi-
tion to the variables summarized in table 1, we also have
detailed information on a graduate’s university and field of
study. Five years after graduation, 5.2% of graduates work
abroad. The main destinations are Switzerland, the United
States, the United Kingdom, Austria, and France (online
appendix table A.2).
B. Data on Earnings Inequality
We classify destination countries as either more or less
equal to Germany using newly constructed measures of earn-
ings inequality for university graduates. Existing inequal-
ity measures, such as Gini coefficients, typically measure
inequality for the overall population, but the decisions of
9 Our focus is on the selection of international migrants. A number of
papers investigate the Roy/Borjas model applied to internal migration,
including Borjas, Bronars, and Trejo (1992), Dahl (2002), Abramitzky
(2009), and Bartolucci, Villosio, and Wagner (2014).
10 Recent papers have highlighted the role of taxes for the migration of
inventors and soccer players (Akcigit, Baslandze, & Stantcheva, 2016;
Kleven, Landais, & Saez, 2013).
11 Between 1993 and 2005, the majority of German university graduates
completed Diplom, Magister, or Staatsexamen degrees. These degrees are
usually completed in four to six years and are considered comparable to
a master’s degree in other countries in standard international classifica-
tions (ISCED 5A, according to the International Standard Classification of
Education).
12 After graduation, many university graduates enroll in additional training
such as legal or teacher traineeships (Referendariat), or Ph.D. programs.
Earnings in the initial survey are thus a noisy measure of earnings potential.
13 The German higher education sector consists of traditional universities,
universities of applied sciences (Fachhochschulen), specialized universi-
ties (focusing on arts, music, or theology), and a small number of private
universities. The best students tend to enroll in traditional universities. To
estimate the Heckman selection model, we also restrict the sample to grad-
uates from universities where at least one graduate works abroad. These
sample restrictions reduce the sample by around 30%. Results that include
all institutions are very similar to our main findings (see online appendix
figure A.4).
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780
THE REVIEW OF ECONOMICS AND STATISTICS
Table 1.—Summary Statistics for German University Graduates
Job characteristics (after five years)
Working abroad
Annual earnings in euro (2001 prices)
Potential experience in months
Postgraduate education
Ph.D. completed
Further (non-Ph.D.) degree completed
Education first degree
Final university grade
Studied abroad
Age at graduation
ERASMUS/total students in subject
Education before first degree
Final school grade
Apprenticeship
Previous mobility
Studied in same state as high school
Personal characteristics
Female
Partner
Married
Child(ren)
Parental background
Mother’s education (years)
Father’s education (years)
Mother self-employed
Mother salaried employee
Mother civil servant
Mother worker
Mother did not work
Father self-employed
Father salaried employee
Father civil servant
Father worker
Father did not work
Observations
Full Sample
Mean
SD
0.052
43,491
69.201
0.191
0.073
2.018
0.078
26.994
0.040
2.110
0.220
0.659
0.445
0.780
0.416
0.291
13.459
14.852
0.092
0.597
0.108
0.100
0.103
0.194
0.447
0.223
0.113
0.023
11,091
–
19,334
4.161
–
–
0.681
–
2.664
0.057
0.639
–
–
–
–
–
–
3.102
3.065
–
–
–
–
–
–
–
–
–
–
Working
in Germany
Abroad
More Equal
Mean
0
43,265
69.197
0.182
0.071
2.032
0.072
27.026
0.039
2.119
0.225
0.663
0.444
0.782
0.421
0.297
13.423
14.816
0.093
0.596
0.105
0.103
0.104
0.191
0.448
0.221
0.116
0.024
10,510
Mean
1
39,458
69.719
0.313
0.125
1.698
0.240
26.271
0.052
1.951
0.094
0.583
0.594
0.740
0.281
0.156
14.458
15.458
0.063
0.677
0.177
0.042
0.041
0.188
0.479
0.271
0.063
0.000
96
Abroad
Less Equal
Mean
1
49,231
69.194
0.371
0.122
1.787
0.169
26.437
0.050
1.959
0.138
0.581
0.445
0.736
0.344
0.184
14.035
15.493
0.091
0.619
0.148
0.049
0.093
0.262
0.406
0.258
0.062
0.012
485
The table shows summary statistics of German university graduates at five years after graduation. Information on earnings is available for 10,315 of the 11,091 graduates. Average annual earnings of 43,491 euros in
2001 prices correspond to around 79,084 U.S. dollars in 2014 prices.
highly skilled migrants will likely depend on the earnings
inequality of university graduates.
Our main data source is the Luxembourg Income Study
(LIS) (2013), which provides access to individual-level earn-
ings surveys from several countries. The database covers
different years for each country. We use all available sur-
vey years for the main destinations of German university
graduates (see table A.3 for available survey years in each
country). Switzerland and Austria are important destinations
for German university graduates but have only relatively lim-
ited coverage in the LIS database. We therefore augment the
LIS data with additional data for Austria (Microcensus 1999
and EU-SILC 2007, 2008) and Switzerland (Labour Force
Survey 1998–2005).
To measure earnings inequality for high-skilled individ-
uals, we restrict the samples in the individual-level income
surveys to university graduates. We further restrict the sam-
ples to full-time employees of working age, and we exclude
individuals who are self-employed, enrolled in educational
institutions, or report negative earnings.
Based on the individual-level surveys, we construct earn-
ings percentiles for each country and available year using the
survey sampling weights (see online appendix table A.3).
Some surveys in the (augmented) LIS data report gross
earnings, while others report net earnings. To measure cross-
country inequality of net earnings, we convert gross into net
earnings using the net personal average tax rate of single
persons without children from the OECD (2013b).14 Data
appendix B.1 provides more detail on the construction of
the inequality measures.
In our main analysis, we use the ratio of the 75th to the
25th earnings percentile (75/25 ratio) for university gradu-
ates to measure earnings inequality across countries. Figure 1
14 The net personal average tax rate is defined as the personal income tax
and employee social security contributions net of cash benefits, expressed
as a percentage of gross wage earnings. The OECD reports three different
tax rates along the earnings distribution: the average tax rate at 67%, 100%,
and 167% of average earnings. We apply the tax rate at 67% of average
earnings to the 25th percentile and below, the tax rate at 100% of average
earnings to earnings between the 25th and the 75th percentile, and the tax
rate at 167% of average earnings to the 75th percentile and above.
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THE SELECTION OF HIGH-SKILLED EMIGRANTS
781
shows the ranking of countries according to the 75:25 ratio
that we average over 1998 to 2010 to reflect the years that
correspond to our graduate surveys (online appendix table
A.4 reports 75:25 ratios for each country). Inequality is high-
est in the United States, followed by France and Poland. The
Scandinavian countries and Australia are most equal. Ger-
many is ranked in the middle.15 We can therefore investigate
the selection of German university graduates into less equal
and more into equal countries.16
C. Data on ERASMUS Places
As part of our estimation procedure, which we explain
below, we use data on the number of ERASMUS places
to correct for potential selection bias. We obtain data on
the number of study-abroad places in the ERASMUS pro-
gram by university, subject, and year from the German
Academic Exchange Service (DAAD). The median inter-
nationally mobile student studies abroad for one or two
semesters about three years before graduation. We assign
the number of ERASMUS places in the corresponding aca-
demic year, subject, and university to each student. To
account for differences in cohort size that affect students’
study-abroad opportunities, we normalize the number of
ERASMUS places with the number of students in the cor-
responding university and subject (for details, see Parey &
Waldinger, 2011).
IV. Methods and Results
A. The Selection of Migrants to More and
Less Equal Destinations
For our analysis, we use predicted earnings to measure
earnings potential in the home country. This measure of
skill represents θ0 in the model we have outlined. We then
use predicted earnings to compare the distribution of skills
of migrants to less equal countries, migrants to more equal
countries, and nonmigrants.
To construct predicted earnings, we estimate an aug-
mented Mincer regression for nonmigrants only:
log w0i = Xiβ0 + ε0i.
(6)
15 Recent papers have used large administrative data sets to document
a rise in German earnings inequality during the past decades (Dustmann,
Ludsteck, & Schönberg, 2009, Card, Heining, & Kline, 2013). In these data
sets, earnings are censored at the maximum of social security contributions.
For university graduates, 42% (13%) of observations for men (women) are
top-coded between 1998 and 2008. Because university graduates are in the
top 11% of the educational distribution, we prefer to use earnings surveys
in the LIS that are not top-coded.
16 As we measure selection with predicted earnings, an ideal measure
of inequality would be based on country-level differences in returns to
observed skills. Such a measure would require graduate data sets with com-
parable characteristics on each graduate for all major destinations. As these
are not available, we use the 75:25 ratio that is based on actual earnings.
The empirical results are valid as long as countries with higher 75:25 ratios
also exhibit higher returns to observed skills.
The estimate of β0 measures returns to skills in the home
country. Our data allow us to include a large number of
variables Xi to obtain a good prediction of earnings poten-
tial. Xi contains variables that measure university experience
(final university grade, age at graduation, completing univer-
sity with a bachelor’s degree, 24 subject fixed effects, and
university fixed effects), additional education after gradua-
tion (completing a Ph.D. or a non-Ph.D. graduate degree),
preuniversity education (final high school grades and appren-
ticeship before studying), previous mobility (moving to
another state between high school and university), potential
labor market experience, personal characteristics (gender,
marital/partnership status, children), parental background
(mother’s and father’s education and occupation), and grad-
uate cohort fixed effects. The coefficients of the augmented
Mincer regression have the expected signs and magnitudes
(table 2, column 1).17 The R2 of about 0.28 is high for a
Mincer regression, suggesting that predicted earnings are an
informative skill measure for university graduates.18
Next, we predict potential earnings in the home country
for migrants and nonmigrants. The predictions are based on
the coefficient vector (ˆβ0) and individual characteristics Xi:
ˆθ0i = Xi ˆβ0.
(7)
We then use this measure of skills to compare three groups
of interest: migrants to less equal countries, migrants to more
equal countries, and nonmigrants. Specifically, we construct
cumulative distribution functions (CDFs) of predicted earn-
ings ˆθ0 by migration group, F(ˆθ0 | Migration status), and plot
them in the left panel of figure 2a.
The dashed line shows the CDF of nonmigrants. The solid
dark line is the CDF of migrants to less equal destinations,
such as the United States. This CDF lies to the right of
the CDF for nonmigrants, indicating that this group is posi-
tively selected in terms of earnings potential. The migrants to
these countries have skills that, according to the returns in
the Mincer regression, are valued more highly than those
of nonmigrants: median log predicted earnings for these
migrants are 10.65 compared to 10.61 for nonmigrants. The
CDFs of nonmigrants and of migrants to less equal countries
do not cross, indicating that these migrants are positively
selected over the full range of predicted earnings. We test
the statistical significance of our findings in section IVC.
The lighter solid line shows the CDF of migrants to
more equal destinations, such as Denmark. It indicates that
migrants to more equal countries are negatively selected rela-
tive to non-migrants. Median log predicted earnings for these
17 Because all graduates are surveyed around five years after gradu-
ation, the variation in potential labor market experience is small, and
estimated coefficients are different from the typical pattern observed in
Mincer regressions. The omitted degree is a Diplom/Magister degree. Com-
pared to graduates with these traditional degrees, graduates sampled after
completing a bachelor’s degree have lower earnings.
18 We show that our results are robust to excluding the controls for children
and marital/partnership status from the wage regression (online appendix
figure A.5).
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THE REVIEW OF ECONOMICS AND STATISTICS
Table 2.—Augmented Mincer Regression for University Graduates in Germany
(1)
(2)
(3)
Dependent Variable
Labor Earnings
Labor Earnings
Working in Germany
OLS
Heckman Selection Model
Selection Equation
Education first degree
Final university grade
Final grade squared
Bachelor’s degree
Age at graduation
Age squared
Postgraduate education
Ph.D. completed
Further (non-Ph.D.) degree completed
Education before first degree
Final school grade
School grade squared
Apprenticeship
Previous mobility
Studied in same state as high school
Potential work experience
Experience in months
Experience squared
Personal characteristics
Female
Partner
Married (additionally)
Child(ren)
Parental background
Mother’s education (years)
Father’s education (years)
Mother self-employed
Mother salaried employee
Mother civil servant
Mother worker
Father self-employed
Father salaried employee
Father civil servant
Father worker
ERASMUS places/students
Mills ratio
Graduate cohort FE
Subject FE
University FE
R2/Pseudo-R2
Observations
0.048∗
−0.023∗∗∗
−0.131∗∗∗
−0.026∗∗
0.000∗
−0.003
−0.024
−0.041
0.009
0.037∗∗∗
−0.010
−0.058∗∗∗
0.000∗∗∗
−0.131∗∗∗
0.066∗∗∗
0.028∗∗∗
−0.040∗∗∗
0.003∗
0.003∗
−0.008
−0.012
−0.019
−0.001
0.054∗∗
0.041∗
0.027
0.003
YES
YES
YES
0.282
9,778
(0.027)
(0.006)
(0.028)
(0.011)
(0.000)
(0.011)
(0.015)
(0.034)
(0.008)
(0.010)
(0.008)
(0.022)
(0.000)
(0.008)
(0.009)
(0.009)
(0.009)
(0.002)
(0.002)
(0.017)
(0.013)
(0.018)
(0.016)
(0.025)
(0.024)
(0.025)
(0.026)
0.046∗
−0.023∗∗∗
−0.132∗∗∗
−0.026∗∗
0.000∗
0.000
−0.021
−0.043
0.010
0.037∗∗∗
−0.012
−0.059∗∗∗
0.000∗∗∗
−0.131∗∗∗
0.065∗∗∗
0.028∗∗∗
−0.041∗∗∗
0.003∗
0.003∗
−0.009
−0.012
−0.019
−0.003
0.056∗∗
0.041∗
0.028
0.003
−0.050
YES
YES
YES
9,778
(0.027)
(0.006)
(0.028)
(0.011)
(0.000)
(0.013)
(0.016)
(0.034)
(0.008)
(0.010)
(0.008)
(0.022)
(0.000)
(0.008)
(0.009)
(0.009)
(0.010)
(0.002)
(0.002)
(0.017)
(0.013)
(0.017)
(0.016)
(0.025)
(0.024)
(0.025)
(0.026)
(0.095)
0.079
−0.007
0.049
−0.013
0.001
−0.367∗∗∗
−0.251∗∗∗
0.109
−0.011
0.078
0.131∗∗∗
0.096
−0.001
−0.047
0.070
0.027
0.210∗∗∗
−0.002
−0.019∗
0.107
0.010
−0.013
0.194
−0.260
−0.053
−0.132
0.009
−1.197∗∗∗
YES
YES
YES
0.132
10,315
(0.203)
(0.048)
(0.158)
(0.097)
(0.002)
(0.065)
(0.085)
(0.224)
(0.052)
(0.071)
(0.049)
(0.138)
(0.001)
(0.053)
(0.058)
(0.058)
(0.065)
(0.010)
(0.010)
(0.112)
(0.086)
(0.112)
(0.122)
(0.195)
(0.192)
(0.196)
(0.209)
(0.424)
Column 1 reports results from the augmented Mincer regression. Column 2 reports results from the augmented Mincer regression that controls for selection in the decision to work in Germany using a Heckman
selection correction. Column 3 reports the corresponding selection equation, which predicts working in Germany with the number of ERASMUS places normalized by the cohort size in a graduate’s university
department. Significance levels: ***p < 0.01, **p < 0.05, *p < 0.1.
migrants are 10.56 compared to 10.61 for nonmigrants. The
differences between the CDFs are substantial and in the same
order of magnitude as standard estimates for the returns to
an additional year of education in the United States (Card,
1999).
Inequality varies across potential destination countries.
We use this variation to analyze selection to countries with
more extreme levels of (in)equality by splitting more and less
equal countries into two groups each. Thus, we now compare
five types of destinations: very unequal, somewhat unequal,
home, somewhat equal, and very equal countries. We classify
the three countries with the most unequal earnings distribu-
tions as very unequal and the three countries with the most
equal distributions as very equal. Results are shown in the
right panel of figure 2a. Very unequal countries receive the
most positively selected migrants, somewhat unequal coun-
tries receive somewhat positively selected migrants, some-
what equal countries receive slightly negatively selected
migrants, and very equal countries receive strongly nega-
tively selected migrants. The CDFs are somewhat noisier
than in the previous graphs because sample sizes of migrants
are relatively small, especially for equal countries. Nonethe-
less, the selection pattern follows the theoretical predictions
for the five groups.19
19 In online appendix figure A.6, we show results where we classify the
four, instead of three, most (un)equal countries as most (un)equal. The
results are very similar.
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THE SELECTION OF HIGH-SKILLED EMIGRANTS
783
Figure 2.—Predicted Earnings of Migrants and Nonmigrants
(a) CDF for Three and Five Groups of Countries
(b) CDF for Three and Five Groups of Countries—Earnings Prediction Corrected for Selection
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(a) CDFs of predicted earnings that are based on returns reported in column 1 of table 2 for three groups: migrants to more equal countries, nonmigrants, and migrants to less equal countries (left panel) and for
five groups: migrants to very equal countries, migrants to somewhat equal countries, nonmigrants, migrants to somewhat unequal countries, and migrants to very unequal countries (right panel). (b) CDFs of predicted
earnings that are based on selection-corrected returns reported in column 2 of table 2 for the same groups of countries. Table 3 reports stochastic dominance tests. Online appendix figure A.2 shows kernel-smoothed
versions of the CDFs.
B. Controlling for Selection in the Augmented
Mincer Regression
As our previous analysis has shown, migrants are sys-
tematically selected from the home population. Unless this
selection is fully accounted for by the observables, the selec-
tion could potentially bias the coefficients of the augmented
Mincer regression and thus our measure of predicted earn-
ings. We use a Heckman selection procedure to control
for this potential selection by estimating a selection equa-
tion that predicts whether a graduate works in Germany or
migrates abroad.
We use the introduction and expansion of the ERASMUS
student exchange program as an instrumental variable that
predicts whether graduates work in Germany. ERASMUS
allows students to study abroad in a European country for
one or two semesters before they continue their studies
in their home country. It was introduced in 1987 and has
increased massively since then. In Germany, about 4,925
students participated in ERASMUS in 1990 (the year when
the typical graduate of the 1993 cohort had studied abroad);
participation rose to 18,482 in 2002 (the year when the typ-
ical graduate of the 2005 cohort had studied abroad). The
program was introduced at different times and expanded at
varying rates, depending on the university and department.
Parey and Waldinger (2011) show that the introduction and
expansion of ERASMUS significantly increased the prob-
ability of graduates moving abroad after completing their
studies in Germany. The ERASMUS instrument success-
fully controls for selection in the Mincer regression if the
number of ERASMUS places in a student’s university can
be excluded from the Mincer regression. Crucially, we do
not use the actual decision to study abroad, but the avail-
ability of department-level ERASMUS scholarship places,
which predict studying abroad and working abroad later on,
to instrument for working in Germany.
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THE REVIEW OF ECONOMICS AND STATISTICS
In our data, the median graduate enrolled in university in
1991–92 and thus before the widespread availability of the
Internet. Before the introduction of the Internet, information
on the number of ERASMUS places was very difficult to
obtain. Even today, few department websites report the exact
number of ERASMUS places. It is therefore unlikely that
students sorted into certain departments to benefit from more
ERASMUS places. To further limit the possiblity of student
sorting, we assign the number of ERASMUS places for the
subject×university combination where a student first enrolls
in university. Any potential sorting after the first enrollment
will therefore not affect the exogeneity of the ERASMUS
instrument.
Students in certain subjects are systematically more likely
to study abroad, and to work abroad later, than students
in other subjects. We control for any such subject-specific
differences by including 24 subject fixed effects in the regres-
sions. A related concern may be that better universities
offer more ERASMUS places and also facilitate working
abroad. We control for these university-specific differences
by including a full set of university fixed effects in the regres-
sions. We also control for broader trends of studying and
working abroad by controlling for cohort fixed effects.
Parey and Waldinger (2011) further discuss the exclusion
restriction of the ERASMUS instrument. They show that the
expansion of ERASMUS in a department is not correlated
with a wider push to increase the international outlook of stu-
dents. They also show that the probability of studying abroad
is completely flat before the introduction of ERASMUS and
increases only once ERASMUS has been introduced, sug-
gesting that pretrends are not affecting the validity of the
ERASMUS instrument.
Column 3 of table 2 shows the first-stage estimates where
we regress whether individuals work in Germany on a
measure of ERASMUS scholarship places (normalized by
the number of students) in a graduate’s university depart-
ment. The availability of ERASMUS significantly lowers
the probability of working in Germany.
Column 2 in table 2 shows that controlling for selection
in the Mincer regression has only a small effect on the esti-
mated coefficients. In addition to the rich set of observables,
this also reflects that the share of graduates not migrating
(and thus observed in our Mincer regression) is very high
and that selection of migrants occurs at both the top and
the bottom of the distribution. The coefficient on the Mills
ratio is therefore quantitatively small and insignificant. The
resulting CDFs of earnings potential by migration status are
presented in figure 2b. They confirm that migrants to less
equal destinations are positively selected, while migrants to
more equal destinations are negatively selected.
C. Tests for Stochastic Dominance
We investigate the statistical significance of the substan-
tial differences between the CDFs with tests for first-order
stochastic dominance. As we estimate the Mincer earnings
equation in the first step of our analysis and construct pre-
dicted earnings based on the Mincer regression, we need
to account for this additional source of uncertainty when
we compute p-values. We therefore apply the bootstrap pro-
cedure for stochastic dominance tests developed in Barrett
and Donald (2003) and described in further detail in online
appendix A.2. We also report p-values from conventional
Kolmogorov-Smirnov tests, which do not account for the
uncertainty associated with the estimation of parameters in
the Mincer regression.
The corresponding test results are shown in table 3. The
top row of panel A indicates that we can reject the null
hypothesis that the more-equal-CDF dominates the CDF
of nonmigrants (“Home”) at the 1% level of significance
(columns 1–3). Similarly, the second row indicates that
we can reject that the CDF of nonmigrants dominates the
more-unequal-CDF at the 10% level. We also reject that
the more-equal-CDF dominates the less-equal-CDF at the
1% level. We even reject these hypotheses when we use
the Heckman selection-corrected estimates, as reported in
columns 4 to 6.
The graphical analysis presented in figure 2 suggests even
more pronounced differences in the CDFs when we limit
the comparison to very equal and very unequal countries,
respectively. Table 3B indeed shows that the test statistic for
the comparison of these more extreme destinations increases
substantially. Because the relevant samples become smaller
for destinations with more extreme levels of inequality, the
p-values do not decrease in all cases. Nonetheless, the test
of stochastic dominance now rejects at the 5% level for all
three comparisons. Table 3B also reports tests for selec-
tion between more similar destinations. The test statistic
always has the predicted sign, suggesting that selection fol-
lows the basic Roy/Borjas model, even for more similar
destinations. As expected, selection patterns to the more sim-
ilar destinations are often not statistically significant because
inequality differences in more similar destinations are much
lower and because some country groups attract relatively
few graduates. We also test the reverse set of hypothe-
ses and cannot reject them. The corresponding p-values are
above 0.74 and in most cases above 0.95 (online appendix
table A.5).
D. Selection of Migrants by Country
Our data also allow us to investigate the selection of
migrants to each of the nineteen destinations in our sample
and thereby go beyond the three or five groups of countries
presented in the previous section. We compute average pre-
dicted earnings of migrants to each country and correlate
them with the 75/25 ratio (figure 3). Circle sizes indicate the
number of migrants in each country. Apart from a few out-
liers, migrants to more equal countries have lower predicted
earnings than migrants to less equal countries.
We estimate a weighted country-level OLS regression and
show the corresponding prediction in figure 3. In particular,
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THE SELECTION OF HIGH-SKILLED EMIGRANTS
785
Table 3.—Stochastic Dominance Tests
OLS
p-Value
Heckman Selection Correction
p-Value
Test
Statistic
(1)
Kolmogorov-
Smirnov
(2)
Barrett-
Donald
(3)
Test
Statistic
(4)
Kolmogorov-
Smirnov
(5)
A. Selection to More Equal and Less Equal Destinations
0.187
0.061
0.220
0.001∗∗∗
0.031∗∗
0.000∗∗∗
0.006∗∗∗
0.098∗
0.001∗∗∗
0.182
0.071
0.218
0.002∗∗∗
0.009∗∗∗
0.000∗∗∗
B. Selection to Very Equal, Somewhat Equal, Somewhat Unequal, and Very Unequal Destinations
Equal versus home
Home versus unequal
Equal versus unequal
Stochastic dominance tests for very equal and very unequal destinations
Very equal versus home
Home versus very unequal
Very equal versus very unequal
0.258
0.144
0.301
Stochastic dominance tests for more similar destinations
0.179
0.147
0.057
0.133
Very equal versus somewhat equal
Somewhat equal versus home
Home versus somewhat unequal
Somewhat unequal versus very unequal
0.007∗∗∗
0.004∗∗∗
0.005∗∗∗
0.231
0.083∗
0.109
0.033∗∗
0.018∗∗
0.017∗∗
0.008∗∗∗
0.379
0.177
0.235
0.101
0.249
0.162
0.301
0.196
0.142
0.065
0.136
0.009∗∗∗
0.001∗∗∗
0.005∗∗∗
0.171
0.099∗
0.055∗
0.027∗∗
Barrett-
Donald
(6)
0.022∗∗
0.083∗
0.004∗∗∗
0.041∗∗
0.014∗∗
0.012∗∗
0.310
0.171
0.173
0.096∗
The table reports one-sided Kolmogorov-Smirnov test statistics and Kolmogorov-Smirnov and Barrett and Donald p-values for CDFs in figure 2. Barrett and Donald p-values are bootstrapped, following equation
(11) in Barrett and Donald (2003, p. 82). In the top row (equal versus home), we test the null hypothesis that the CDF of migrants to more equal destinations stochastically dominates the CDF of nonmigrants, and
similarly for other rows. The bootstrap is based on 4,999 replications. See text for details. Significance levels: ***p < 0.01, **p < 0.05, *p < 0.1.
Figure 3.—Predicted Earnings and Inequality Across Destinations
V. Robustness
FI
AU
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CH
IE
DE
NL
.
7
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1
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6
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1
DK
US
AT
ES
PL
FR
IT
GB
JP
CA
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SE
NO
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1.3
1.5
1.7
75/25 ratio
1.9
The figure shows average predicted earnings for migrants to each country and the corresponding 75:25
inequality ratio. Circle sizes are proportional to the number of migrants in each destination. The regression
line reported in the figure is estimated in a weighted regression with weights equal to the number of
migrants in each country. The slope coefficient is equal to 0.153 with a standard error of 0.081. An
unweighted regression has a slope equal to 0.103 with a standard error of 0.101. For country labels, see
data appendix table B.2.
we regress average predicted earnings (
in each country c:
¯ˆθ0c) on the 75/25 ratio
¯ˆθ0c = γ0 + γ175/25 ratioc + εc.
(8)
The estimated regression line (ˆγ1) has a slope of 0.153
with a standard error of 0.081 (table 4, column 1, significant
at the 10% level). This estimate indicates that migrants to
destinations with a 75:25 ratio that is higher by 0.4 (the
difference between Germany and the United States) have
predicted earnings that are 6.1 log points higher.
A. Controlling for Possible Confounding Factors
The selection pattern described in the previous section is
consistent with the theoretical predictions of the Roy/Borjas
model. Earnings inequality, however, is not the only factor
that differs between home and destination countries. Coun-
tries may also differ along other dimensions that could be
correlated with migrant selection.
We first analyze whether confounding factors (Fc) are
driving our selection results by controlling for them in the
cross-country regression (table 4):
¯ˆθ0c = γ0 + γ175/25 ratioc + γ2 Fc + εc.
(9)
The Roy/Borjas model predicts that mean earnings should
affect the number of migrants to each country but not the
direction of selection. Nonetheless, differences in mean earn-
ings will affect migration choices and may be correlated
with differences in the 75:25 ratios. In our first robust-
ness check, we therefore control for average log earnings
in each country. In this specification, the coefficient on
the 75:25 ratio increases slightly to 0.180, suggesting an
even stronger relationship between inequality and migrant
selection (column, 2, significant at the 1% level). Migra-
tion decisions, especially those of lower-skilled migrants
(within the high-skilled population), may also be affected
by expected unemployment spells. When we control for
unemployment rates of tertiary-educated individuals, the
coefficient on the 75:25 ratio is equal to 0.174 (column 3,
significant at the 5% level). Migration decisions may also
be affected by differences in child care provision. When
we control for public expenditures on family benefits, the
coefficient on the 75:25 ratio is equal to 0.110 (column 4,
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786
THE REVIEW OF ECONOMICS AND STATISTICS
75/25 ratio
Mean earnings
Tertiary-educated unemployment share
Family expenditure
Life satisfaction
Constant
R2
Observations
Table 4.—Cross-Country Regressions
(1)
0.153∗
(0.081)
(2)
0.180∗∗∗
(0.058)
0.110∗∗∗
(0.033)
(3)
0.174∗∗
(0.077)
−0.007
(0.007)
10.366∗∗∗
(0.144)
0.183
19
9.161∗∗∗
(0.413)
0.475
19
10.353∗∗∗
(0.138)
0.204
19
(4)
0.110∗
(0.057)
(5)
0.247∗∗∗
(0.081)
−0.023∗
(0.011)
10.484∗∗∗
(0.104)
0.317
19
0.050∗
(0.024)
9.849∗∗∗
(0.276)
0.282
19
(6)
0.147∗
(0.071)
0.102∗
(0.056)
0.005
(0.009)
−0.012
(0.011)
0.003
(0.036)
9.281∗∗∗
(0.531)
0.514
19
The table reports weighted regressions of average predicted earnings of migrants in each country on the corresponding 75/25 ratio and potential confounders. See data appendix B.2 for details on data sources and
data appendix table B.2 for country data. Significance levels: ***p < 0.01, **p < 0.05, *p < 0.1.
significant at the 10% level). Migration decisions may also
be affected by expectations about general well-being. When
we control for a measure of life satisfaction, the coefficient
on the 75:25 ratio is 0.247, confirming a strong relationship
between earnings inequality and migrant selection (column
5, significant at the 1% level). When we control for all poten-
tial confounders at the same time, the coefficient on the 75:25
ratio is 0.147, with a p-value of 0.061 (column 6).
The previous checks confirm a robust effect of earnings
inequality on mean selection levels. In additional tests, we
investigate how potential confounders affect selection across
the whole distribution of skills. For these tests, we first
replicate the CDFs from our main results using quantile
regressions and then control for possible confounding factors
using the quantile regression framework. We regress pre-
dicted earnings of each individual i (ˆθ0i) on country group
dummies separately for 100 centiles (τ = 0.01, . . . , 0.99) of
the predicted earnings distribution:
ˆθ0ic = δ0τ + δ1τVery Equalic
+ δ2τSomewhat Equalic
+ δ3τSomewhat Unequalic
+ (cid:3)icτ.
+ δ4τVery Unequalic
(10)
is much more equal
Very Equalic takes a value of 1 if the individual works
in a country that
than Germany,
Somewhat Equalic takes a value of 1 if the individual works
in a country that is somewhat more equal, and so on. The con-
stant represents predicted earnings for individuals who work
in Germany. Online appendix figure A.7a shows the quantile
regression equivalents of the CDFs in our main results. We
then control for potential confounding factors in the quantile
regressions by adding country-level controls:
ˆθ0ic = δ0τ + δ1τVery Equalic
+ δ3τSomewhat Unequalic
+ δ5τFc + (cid:3)icτ.
+ δ2τSomewhat Equalic
+ δ4τVery Unequalic
(11)
From the estimated coefficients, we predict CDFs for each
group holding constant the value of the added covariate at
the German level. Panels b to f of online appendix figure
A.7 show CDFs that are adjusted for the same confounding
factors that we have analyzed in the cross-country regres-
sion (table 4). The selection pattern to locations with more
extreme levels of (in)equality is robust to controlling for
potentially confounding factors. The selection pattern to
locations with less extreme levels of (in)equality remains
broadly consistent with the predictions of the model (see
online appendix table A.7 for stochastic dominance tests).
If we control for mean earnings, the CDF for somewhat
unequal countries sometimes moves to the left of the CDF for
graduates at home. However, the stochastic dominance tests
indicate that the two CDFs are not significantly different.
B. Sensitivity of Results to Alternative Inequality Measures
In appendix section A.4, we investigate the sensitivity of
our main results to using alternative measures of inequal-
ity. We show that the results are very similar for a range of
inequality measures that we calculate for the overall popu-
lation, including the 90:50 ratio, the 75:25 ratio, the 90:10
inequality ratio, the Gini coefficient, and the Theil index.
C. Selection to Europe and to Austria/Switzerland
Additionally, we investigate selection to European coun-
tries only. German citizens who migrate to these countries
face virtually no migration barriers, such as visa require-
ments. Germans can settle freely in any country of the
European Union and in other European countries, such
as Switzerland, Lichtenstein, and Norway.20 Furthermore,
migration costs to these countries are relatively low because
distances within Europe are small, and travel costs are low.
We plot CDFs of predicted earnings of migrants to less
equal countries, migrants to more equal countries, and non-
migrants (figure 4a). As for the full sample, migrants to
more equal European countries are negatively selected, and
migrants to less equal European destinations are positively
20 Graduates from the 1993 to 2001 cohorts who migrated to Poland or
Switzerland had minor restrictions to settle in these countries.
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THE SELECTION OF HIGH-SKILLED EMIGRANTS
787
Figure 4.—Predicted Earnings of Migrants to Europe and Austria/Switzerland
(a) Europe
(b) Austria and Switzerland
1
5
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2
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10.2
1
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0
Equal (N=89)
Home (N=10,510)
Unequal (N=386)
11
11.2
10
10.2
Home (N=10,510)
Austria and Switzerland (N=194)
10.4
10.6
Log predicted earnings
10.8
11
11.2
10.4
10.6
Log predicted earnings
10.8
The figure shows CDFs of predicted earnings (prediction based on selection-corrected returns reported in column 2 of table 2) for migrants to Europe—EU countries (2005), Norway, and Switzerland—and nonmigrants
in panel a; and to Austria or Switzerland and nonmigrants in panel b. Online appendix table A.9 (panels A and B) reports stochastic dominance tests.
selected, compared to nonmigrants.21 These results suggest
that differential migration costs are not driving our main
results.
We also investigate migrant selection to Austria and
Switzerland only. These two countries are very similar to
Germany along many dimensions that may affect migration
choices. The countries have similar education systems with
very similar university graduation rates (OECD, 2013a). The
countries also have similar unemployment benefits as mea-
sured by replacement rates that ranged between 29% and
33% of gross incomes in 2005 (OECD, 2015). The three
countries also share a similar culture. Finally, Austria is
German speaking, and in Switzerland, 64% of the popu-
lation is German speaking, and more than 90% of German
migrants settle in predominantly German-speaking regions
of Switzerland (Bundesamt für Statistik, 2010, 2013). While
the three countries are similar along many dimensions, they
differ in earnings inequality. Both Austria and Switzerland
are less equal than Germany. The CDF of predicted earnings
of migrants to Austria and Switzerland lies to the right of
the nonmigrant CDF (figure 4b).22 These results indicate that
migrants to Austria and Switzerland are positively selected
compared to nonmigrants, as predicted by the Roy/Borjas
model.
VI. Further Results
A. Decomposing Migrant Selection
Predicted earnings can be considered a summary measure
of different skills. To understand the characteristics that
21 We reject that the CDF of migrants to more equal countries dominates
the home CDF at the 5% level (online appendix table A.9). As Europe
contains few countries with very high inequality, we no longer reject that the
home CDF dominates the CDF of migrants to less equal countries ( p-value
of 0.19).
22 The test that the home CDF dominates the Austria/Switzerland CDF is
rejected at the 10% level (online appendix table A.9, panel B).
underlie the observed selection, we use a Blinder-Oaxaca
procedure, decomposing the overall difference in predicted
earnings into the contribution of each characteristic. For
expositional purposes we group characteristics into thirteen
categories.
The positive selection of migrants to less equal coun-
tries mostly reflects their university career (figure 5, panel
a1). They have better grades and attend better universities
than nonmigrants. The negative selection of migrants to
more equal countries reflects their university subject, uni-
versity quality, and gender (panel a2). They study subjects
with lower returns in the labor market, enroll at universities
with less favorable labor market prospects, and are more
often female. Interestingly, migrants to more equal coun-
tries have better grades at university, despite being negatively
selected overall. This is consistent with findings suggesting
that migrants are positively selected when skill is measured
in terms of education. Decomposition results that use coef-
ficients from the selection-corrected Mincer regression are
shown in online appendix figure A.9.
Columns 1 to 4 of table 5 summarize how the covariates
of the decomposition line up with the overall prediction.
For most characteristics, the table shows no significant devi-
ations from the model predictions. However, there are a
number of interesting differences in the relevance of indi-
vidual characteristics between less equal and more equal
countries. For less equal countries, the pattern of selection
in terms of apprenticeship training is not in line with our
baseline prediction, and for more equal countries, univer-
sity grades show significant positive selection among the
migrants. Although we do not have the detailed data to
investigate these instances, they may reflect heterogeneity
in returns to characteristics across countries or a correlation
of these characteristics with the willingness to move in a
way not captured by the model. For example, it is plausible
that (former) apprentices may realize a higher return to their
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788
THE REVIEW OF ECONOMICS AND STATISTICS
Figure 5.—Decomposition of Predicted Earnings
(a) Migrants to Less Equal and More Equal Countries
(a1) Migrants to less equal countries
Total
University grade
University subject
University FE
Bachelor
Further studies
School grade
Apprenticeship
Previous mobility
Age/Experience
Gender
Partner/Children
Parental background
Graduate cohort
Total
University grade
University subject
University FE
Bachelor
Further studies
School grade
Apprenticeship
Previous mobility
Age/Experience
Gender
Partner/Children
Parental background
Graduate cohort
Total
University grade
University subject
University FE
Bachelor
Further studies
School grade
Apprenticeship
Previous mobility
Age/Experience
Gender
Partner/Children
Parental background
Graduate cohort
Total
University grade
University subject
University FE
Bachelor
Further studies
School grade
Apprenticeship
Previous mobility
Age/Experience
Gender
Partner/Children
Parental background
Graduate cohort
(a2) Migrants to more equal countries
−0.1
−0.08
−0.06
−0.04
−0.02
0
0.02
0.04
0.06
(b) Migrants to Very Unequal and Very Equal Countries
(b1) Migrants to very unequal countries
(b2) Migrants to very equal countries
(p=0.022)**
(p=0.000)***
(p=0.893)
(p=0.044)**
(p=0.279)
(p=0.486)
(p=0.831)
(p=0.002)***
(p=0.223)
(p=0.025)**
(p=0.959)
(p=0.718)
(p=0.001)***
(p=0.210)
(p=0.017)**
(p=0.000)***
(p=0.006)***
(p=0.460)
(p=0.052)*
(p=0.441)
(p=0.948)
(p=0.005)***
(p=0.362)
(p=0.137)
(p=0.004)***
(p=0.771)
(p=0.080)*
(p=0.983)
(p=0.006)***
(p=0.000)***
(p=0.560)
(p=0.188)
(p=0.518)
(p=0.856)
(p=0.735)
(p=0.021)**
(p=0.257)
(p=0.039)**
(p=0.109)
(p=0.729)
(p=0.025)**
(p=0.543)
(p=0.006)***
(p=0.000)***
(p=0.000)***
(p=0.611)
(p=0.115)
(p=0.607)
(p=0.857)
(p=0.049)**
(p=0.583)
(p=0.244)
(p=0.047)**
(p=0.115)
(p=0.914)
(p=0.312)
−0.18−0.16−0.14−0.12 −0.1 −0.08−0.06−0.04−0.02 0
0.02 0.04 0.06 0.08 0.10
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Panel a1 decomposes the mean difference in predicted earnings between migrants to less equal countries and nonmigrants. The top bar (black) measures the total difference in predicted earnings. The other bars
decompose the total difference into the contributions of groups of characteristics (e.g., university grades). More specifically, the size of the gray bars in panel a1 is obtained by multiplying estimated returns (ˆβHome
) for
nonmigrants from column 1 in table 2 (where k indexes a group of characteristics, e.g., all parental background variables or all university fixed effects) with average characteristics of migrants to less equal countries
(xLess equal
. Panel a2 presents the equivalent decomposition between migrants to more equal destinations and
nonmigrants. Panel b presents corresponding results to very unequal and very equal countries. Diamonds indicate 90% confidence intervals. Confidence intervals and p-values are obtained from bootstrapped standard
errors (based on 4,999 replications). Significance levels: ***p < 0.01, **p < 0.05, *p < 0.1.
) and average characteristics of nonmigrants (xHome
), and then subtracting ˆβHome
from ˆβHome
xLess equal
k
xHome
k
k
k
k
k
k
THE SELECTION OF HIGH-SKILLED EMIGRANTS
789
Table 5.—Summary of Decomposition Results
(1)
Less Equal
Destinations
(2)
More Equal
Destinations
(3)
Very Unequal
Destinations
(4)
Very Equal
Destinations
(5)
United States
Total
University grade
University subject
University fixed effect
Bachelor
Further studies
School grade
Apprenticeship
Previous mobility
Age/experience
Gender
Partner/children
Parental background
Graduate cohort
Consistent
Consistent
–
Consistent
–
–
–
Reject
–
Consistent
–
–
Consistent
–
Consistent
Reject
Consistent
–
–
–
–
Consistent
–
–
Consistent
–
–
–
Consistent
Consistent
–
–
–
–
–
Reject
–
Consistent
–
–
Consistent
–
Consistent
Reject
Consistent
–
–
–
–
Consistent
–
–
Consistent
–
–
–
Consistent
Consistent
–
–
Consistent
–
–
Reject
–
Consistent
Consistent
–
Consistent
–
The table summarizes results from the Blinder-Oaxaca decomposition shown in figures 5 and 6a. “Consistent” indicates that the selection along the corresponding characteristic is significantly different from 0 at a
5% level of significance and in line with the model prediction. “Reject” indicates that the selection along the corresponding characteristic is significantly different from 0 at a 5% level of significance, in the direction
not in line with the model prediction.
training in their home labor market and are therefore more
attached to their home labor market.
It is important to keep in mind that figure 5 shows the
results of a statistical decomposition and that the char-
acteristics may be correlated with each other. Predicted
earnings provide a natural way of combining the individual
characteristics in a summary measure.
B. Migration to the United States
Migrants to the United States compared to nonmigrants in
Germany.
In the final section, we investigate migrant selec-
tion to the United States. The United States is an important
destination for university graduates from Germany. In our
sample, more than 13% of graduates who go abroad move to
the United States; only Switzerland attracts more graduates
from Germany. Because U.S. inequality is highest among
the major destinations of German university graduates, we
expect that German university graduates who migrate to the
United States are particularly positively selected.
The CDF of migrants to the United States always lies
to the right of the nonmigrant CDF (left panel of figure
6a). The difference between the CDFs of U.S. migrants
and nonmigrants is more pronounced than the difference
between the CDFs of all migrants to less equal countries and
nonmigrants. This highlights the particularly positive selec-
tion of migrants to the United States. The test of stochastic
dominance is rejected at the 5% level (see online appendix
table A.9, panel C).
As above, we decompose the difference in predicted earn-
ings between migrants to the United States and nonmigrants.
U.S. migrants are positively selected according to almost all
characteristics, in particular characteristics that relate to the
university career and gender. Migrants to the United States
study subjects with especially high returns (see the third bar
from the top in the right panel of figure 6a). They are par-
ticularly concentrated in STEM fields. In our sample, about
17.2% of migrants to the United States hold a degree in
physics (but only 3.9% of nonmigrants), 9.2% hold a degree
in biology (nonmigrants: 2.3%), and 8.1% hold a degree
in chemistry (nonmigrants: 3.0%). Furthermore, migrants to
the United States are also more likely to hold degrees in com-
puter science, economics and management, geography, and
engineering, and they are less likely to hold degrees in law,
languages, medicine, architecture, and education. Migrants
to the United States also obtain higher grades in university
than nonmigrants and study in universities where graduates
have higher predicted earnings.
The decomposition indicates that the United States attracts
high-skilled migrants from Germany who have studied in
better universities, received higher grades, and are concen-
trated in high-paying STEM fields. Thus, migrants to the
United States are precisely those who are considered to be
important for innovation and technological progress.
Migrants from Germany compared to U.S. natives in the
ACS. Finally, we investigate how high-skilled migrants
from Germany fare in the U.S. labor market by comparing
earnings potential of high-skilled migrants from Germany
to high-skilled natives in the United States. For this test, we
use data from the American Community Survey (ACS) and
identify high-skilled migrants from Germany as individuals
born in Germany to non-U.S. parents, migrated to the United
States between 1996 and 2010, and were at least 25 years
old at the time of migration. These restrictions ensure that
our sample of Germans in the United States is as similar as
possible to the sample of graduate emigrants from Germany
whom we study in our main results. To focus our analysis on
the highly skilled, we limit the sample to individuals with a
bachelor’s degree or higher, who worked for 50 to 52 weeks
per year in full-time jobs, and are 30 to 45 years old (see
data appendix B.3 for further details on the ACS data).23
23 Results are similar if we restrict the ACS sample to graduates in more
academically oriented subjects to further increase the comparability with
graduates from traditional universities in Germany.
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THE REVIEW OF ECONOMICS AND STATISTICS
Figure 6.—Predicted Earnings of Migrants to the United States
(a) Based on Returns German Sample (DZHW Data)
1
5
7
.
0
5
.
0
5
2
.
0
0
1
5
7
.
0
5
.
0
5
2
.
0
0
Total
University grade
University subject
University FE
Bachelor
Further studies
School grade
Apprenticeship
Previous mobility
Age/Experience
Gender
Home (N=10,510)
US (N=87)
11
11.2
Partner/Children
Parental background
Graduate cohort
(p=0.003)***
(p=0.000)***
(p=0.127)
(p=0.492)
(p=0.000)***
(p=0.857)
(p=0.705)
(p=0.030)**
(p=0.287)
(p=0.027)**
(p=0.030)**
(p=0.456)
(p=0.018)**
(p=0.475)
−0.02
0
0.02 0.04 0.06 0.08
0.1
0.12
10
10.2
10.4
10.6
Log predicted earnings
10.8
(b) Based on Returns U.S. Sample (ACS Data)
Total
University degree
University subject
Age
Gender
Partner/Children
Graduate cohort
(p=0.000)***
(p=0.000)***
(p=0.000)***
(p=0.000)***
(p=0.000)***
(p=0.169)
(p=0.924)
10
10.5
11
11.5
12
US natives (N=289,538)
Germans (N=565)
Log predicted earnings
0
0.05
0.1
0.15
0.2
0.25
(a) The left panel shows CDFs of predicted earnings (prediction based on selection-corrected returns reported in column 2 of table 2) for migrants to the United States and for nonmigrants. Online appendix table A.9
(panel C) reports stochastic dominance tests. The right panel decomposes the mean difference in predicted earnings between migrants to the United States and nonmigrants. The top bar (black) measures the total
difference in predicted earnings. The other bars decompose the total difference into the contributions of groups of characteristics (e.g., university grades). (b) The left panel shows CDFs of predicted earnings in the
United States. Prediction based on coefficients of the Mincer regression reported in online appendix table A.10 (column 1) using American Community Survey (ACS) data on U.S. natives. The right panel shows a
decomposition of predicted earnings that decomposes the mean difference in predicted earnings between German migrants to the United States and U.S. natives. Diamonds indicate 90% confidence intervals. Confidence
intervals and p-values are obtained from bootstrapped standard errors (based on 4,999 replications). Significance levels: ***p < 0.01, **p < 0.05, *p < 0.1.
We then compare predicted earnings of migrants from
Germany to earnings of U.S. natives. We evaluate the skills
of German immigrants to the United States using pre-
dicted earnings that we construct from returns to skills for
U.S. natives (see online appendix table A.10, column 1 for
returns to skills for U.S. natives). In terms of the Roy/Borjas
model, this test compares the distribution of ˆθ1 of German
migrants in the United States to U.S. natives, while our pre-
vious results compared distributions of ˆθ0 of migrants and
nonmigrants.24 Indeed, our results show that compared to
high-skilled U.S. natives, recent migrants from Germany
have far higher predicted earnings in the U.S. labor mar-
ket. The CDF of predicted earnings of German immigrants
lies to the right of the native CDF along the whole earn-
ings distribution (left panel of figure 6b). At the median, log
24 Parallel
to equation (5),
tion in terms of earnings potential
σθ
E(θ1|Migrate=1) = μ1 +
− ρθ
(cid:7)
(cid:6)
1
σθ
σθ
0
σθ
0
σv
1
φ(z)
1−Φ(z) .
the corresponding equation for selec-
in the destination country is
predicted earnings of migrants from Germany are 11.383,
while log earnings of natives are 11.129. At the 25th and
75th percentiles, migrants from Germany have predicted
earnings of 11.193 and 11.554, while natives have predicted
earnings of 10.937 and 11.334. A back-of-the-envelope cal-
culation suggests that the stronger selection in terms of θ1
(relative to our earlier results in terms of θ0) can be recon-
ciled with our theoretical prediction, both qualitatively and
quantitatively.25
(cid:5)
(cid:5)
(cid:4)
− ρθ
σθ1 /σθ0
ρθ − σθ0 /σθ1
25 The selection in terms of θ1 should be stronger than selection in terms
(cid:4)
of θ0 by a factor of
/
. Between the United
States and Germany, the ratio σθ0 /σθ1 is about 0.8 in our data. While ρθ is
unknown, the positive selection in terms of θ0 indicates that ρθ is above 0.8,
from equation (5). Suppose ρθ = 0.9; then the factor results in a value of
3.7, which is broadly similar but slightly larger than the observed difference
in selection. Because the factor decreases in ρθ, it is straightforward to
reconcile the observed difference in selection with a value of ρθ somewhat
above 0.9.
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THE SELECTION OF HIGH-SKILLED EMIGRANTS
791
Overall, these results indicate that high-skilled individuals
who migrate from Germany to the United States are not only
positively selected compared to Germans who do not migrate
but also compared to nonmigrants in the United States. To
investigate the contribution of different characteristics, we
also decompose the difference in predicted earnings between
German migrants to the United States and U.S. natives.
Because the ACS data are less detailed than our graduate
survey data, the decomposition involves fewer characteris-
tics. Compared to U.S. natives, German migrants have more
advanced degrees (such as professional degrees or Ph.D.s)
and graduated in subjects (in particular, STEM subjects) that
typically lead to higher-paid employment. German migrants
are also less likely to be female than U.S. natives. Over-
all, the positive selection compared to U.S. natives reflects
similar characteristics as the ones we find for the positive
selection compared to German nonmigrants.
VII. Conclusion
The seminal work of Borjas has emphasized how migrant
selection is driven by inequality in home and destination
countries: high-skilled individuals benefit from the upside
opportunities in less equal countries, and low-skilled indi-
viduals benefit from the insurance of a more compressed
wage distribution in more equal countries. This insight has
motivated various empirical tests of the Borjas model. In
spite of the large differences in inequality across many
home-destination country pairs, the empirical evidence is
mixed.
In this paper, we investigate selection within the group
of high-skilled migrants in a setting where migration costs
are particularly low. We use predicted wages to measure
the skills of migrants and graduates who remain at home.
Consistent with the predictions of the basic Roy/Borjas
model, we find that migrants to more equal countries, such
as Denmark, are negatively selected compared to nonmi-
grants. Migrants to less equal countries, such as the United
States, are positively selected. In further results, we show that
migrant selection follows the predictions of the Roy/Borjas
model even within subgroups of either more or less equal
countries.
Our results are robust to controlling for potentially con-
founding factors and using alternative measures of inequality
in destination countries. We also demonstrate that the selec-
tion pattern holds when we study migration within Europe,
and migration to Austria and Switzerland, where barriers to
migration are particularly low. When we decompose pre-
dicted earnings into various skill components, we find that
selection patterns follow the model prediction for most, but
not all, characteristics, suggesting that the choice of the skill
measure can affect findings of migrant selection.
Overall, our findings highlight the importance of the
Roy/Borjas model for the selection of high-skilled migrants.
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