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 Immigration and Domestic Wage:
 An Empirical Study on Competition among Immigrants
 DRAFT – DO NOT QUOTE
 Chong-Uk Kim
 Department of Economics
 Sonoma State University
 1801 E. Cotati Avenue
 Rohnert Park, CA 94928-3609 USA
 Email: [email protected]
 I. Introduction
 The dropping of the Mayflower’s anchor at Cape Cod in 1620 marks the
 beginning of the United States’ long history of immigration. Following this event,
 immigration, through its massive and successive waves, has carved the image of the
 United States. Due to its concordance with domestic economic issues, immigration policy
 continues to be a center of social debate. This is evident in the frequent headlining of the
 President’s actions on immigration in newspapers all over the country.
 The main concerns regarding immigration reform center around the expectation,
 or fear, that new immigrants entering a domestic labor market will replace and take
 opportunity away from native workers while decreasing domestic wages. These concerns
 have spurred many research efforts that provide a wide range of empirical findings. For
 example, some studies such as Borjas (2003) and Mishra (2007) find that immigration
 has a significant impact on wages in both receiving and sending countries while other
 studies such as Card (2005) and Ottaviano and Peri (2012) show that there is no
 meaningful impact of immigration on domestic labor markets.
 While studies on the wage effects of immigration focus on native workers, there is
 significantly less information on the wage effects of immigration on domestic foreignborn
 workers. In addition to analyzing the impact of immigration on wages of native
 workers, in this paper, we estimate the internal competition amongst foreign-born
 workers in the United States. Firstly, using data from the Current
 Population
 Survey
 (CPS),
 we
 find
 no
 empirical
 evidence
 supporting the substitutability of native workers
 immigrants. Secondly, there is no statistical difference between skilled and unskilled
 immigrants on the influence of the domestic labor market outcomes. Lastly, there is no
 internal competition among immigrants. The income of non-citizen workers mainly
 depends on state and national levels of economic situations, not the number of noncitizen
 workers available in the labor market.
 The paper proceeds as follows. Section II describes the literature on the effects of
 immigration on domestic wages. Section III provides the empirical methodology and the
 data used in this analysis. Section IV discusses empirical results and Section V
 concludes.
 II. Literature Review
 The main focus of the majority of immigration literature is to empirically prove if
 immigration suppresses domestic wages. In other words, primary to these studies is the
 degree of substitutability of immigrants for domestic native workers. The general
 conclusion has been that a 10 percent increase in the population due to immigration
 decreases wages of native workers by 1 to 4 percent.1 Using US census data, Altonji and
 Card (1991) measure the impact of immigration on wages of unskilled native workers;
 their findings indicate that a 10 percent increase in the population due to immigration
 lowers wages of unskilled native workers by 1.2 percent even though the effects of
 immigration on wages heavily depend on native subgroup.
 Immigration supporters most frequently cite Card’s famous 1990 paper on Cuban
 boat people. In 1980, more than 125,000 unskilled Cubans immigrated to Miami. Card
 finds no empirical evidence to support the theory that these immigrants lower domestic
 wages or increase unemployment rates of either Cubans or non-Cubans. Butcher and
 Card (1991), Card and DiNardo (2000), Card (2001, 2005) and more recently Henrickson
 and Kim (2012) also find no empirical evidence supporting a strong degree of
 substitutability of immigrants for native workers.
 In contrast, a series of publications by Borjas (1995, 2003, and 2006), report
 empirical evidence that an influx of immigrants decreases wages of native workers and
 affects domestic labor market outcomes. Immigration critics frequently cite Borjas’s
 famous 2003 paper that treats immigration as an increase in national labor supply. This
 study finds that a 10 percent increase in the population due to immigration suppresses
 wages of native workers by 3 to 4 percent.
 While the majority of studies on immigration have focused on the supply side of
 labor market, Lach (2007) suggests that immigrants not only increase domestic labor
 1
 Examples
 of
 such
 results
 are
 numerous,
 but
 include:
 Friedberg
 and
 Hunt
 (1995),
 Borjas
 (2003),
 Borjas,
 Grogger,
 and
 Hanson
 (2010).
 supply, but also increase the demand for domestic output. Companies must hire more
 labor to supply more output; therefore, immigrants eventually shift both labor supply and
 demand curves outward to the right. More recently, without perfect substitutability, Peri
 (2012) and Ottaviano and Peri (2012) show that immigrants do not replace native
 workers and there is no short-run effect on wages of native workers.
 III. Empirical Model and Data
 1. Empirical Model
 Our empirical model which we use to test the main hypothesis is based on the
 standard Mincer earning equation. Since Jacob Mincer published his seminal book
 Schooling, Experience, and Earnings in 1974, many labor economists have used his
 earning equation as a key empirical framework. In the standard Mincer equation, your
 earnings depend on your years of schooling and working experience.
 (1) ln(Y) = a + ß1S + ß2E + ß3E2 + u
 where
 Y
 is
 earnings,
 S
 is
 years
 of
 schooling,
 and
 E
 is
 years
 of
 working
 experience.2
 This
 equation
 (1)
 has
 been
 used
 as
 a
 starting
 point
 of
 many
 empirical
 economic
 papers
 on
 income
 determination.
 Based
 on
 the
 individual
 research
 purposes,
 this
 standard
 equation
 has
 been
 modified
 and
 tested
 in
 many
 academic
 papers.3
 To
 test
 our
 main
 hypothesis,
 we
 modify
 Equation
 (1)
 to
 implement
 our
 model.
 Since
 the
 Current
 Population
 Survey
 (CPS)
 does
 not
 report
 information
 on
 the
 working
 experience,
 first,
 we
 use
 an
 age
 variable
 as
 a
 proxy
 for
 the
 working
 experience.
 Second,
 instead
 of
 using
 a
 years
 of
 schooling
 variable,
 we
 use
 a
 ratio
 of
 high--skilled
 and
 low--skilled
 workers
 to
 capture
 the
 impact
 of
 education
 on
 income.4
 Third,
 we
 2
 a
 is
 a
 constant
 term.
 It
 is
 the
 logarithm
 of
 the
 income
 level
 with
 no
 years
 of
 schooling
 and
 no
 working
 experience.
 u
 is
 a
 Gaussian
 white
 noise
 error
 term.
 3
 Lemieux (2006) provides a nice summary of works using Mincer equations.
 4
 Details
 on
 this
 variable
 will
 be
 given
 in
 the
 next
 section.
 include
 a
 state--level
 unemployment
 rate
 variable
 to
 reflect
 each
 of
 US
 states
 economic
 situation.
 Similarly,
 we
 add
 a
 national--level
 real
 Gross
 Domestic
 Product
 (GDP)
 variable
 to
 consider
 the
 US
 national
 economy.
 Finally,
 we
 include
 the
 total
 number
 of
 foreign
 workers
 which
 is
 our
 key
 variable
 to
 see
 the
 effects
 of
 immigration
 on
 domestic
 wages.
 (2)
 Yit
 =
 a(FOREIGNit)ß(GDPt)?exp(dRATIOit+?UNEMit+?AGEit+?AGE2it+uit)
 where
 Yit
 denotes
 the
 real
 income
 of
 US
 citizens
 of
 state
 i
 in
 period
 t;
 FOREIGNit
 denotes
 the
 total
 number
 of
 foreign
 workers
 of
 state
 i
 in
 period
 t;
 GDPt
 denotes
 the
 real
 GDP
 of
 US
 in
 period
 t;
 RATIOit
 denotes
 the
 ratio
 of
 high--skilled
 and
 low--skilled
 US
 citizens
 of
 state
 i
 in
 period
 t;
 UNEMit
 denotes
 the
 unemployment
 rate
 of
 state
 i
 in
 period
 t;
 AGEit
 denotes
 the
 median
 age
 of
 US
 citizens
 of
 state
 i
 in
 period
 t;
 AGE2it
 denotes
 the
 square
 of
 AGEit
 variable;
 and
 finally
 uit
 is
 a
 Gaussian
 white
 noise
 error
 term.
 We take natural logs on both sides of equation (2) to implement our income equation and
 it provides us the following estimation equation:
 (3) ln(Yit)
 =
 C
 +
 ß
 ln(FOREIGNit)
 +
 ?
 ln(GDPt)
 +
 d
 (RATIOit)
 +
 ?
 (UNEMit)
 +
 ?
 (AGEit)
 (+/--)
 (+)
 (+)
 (--)
 (+)
 +
 ?
 (AGE2it)
 +
 uit
 5
 (-)
 5
 C
 =
 ln(a)
 which
 is
 a
 constant
 term.
 Based on findings from previous research efforts, we expect that the coefficients of GDPt,
 RATIOit,
 and
 AGEit
 variables
 are
 positive
 while
 the
 coefficients
 of
 UNEMit
 and
 AGE2it
 variables
 are
 negative.
 A
 positive
 coefficient
 of
 our
 key
 variable,
 FOREIGNit,
 will
 support
 the
 complementarity
 idea
 between
 immigrants
 and
 citizen.
 Similarly,
 a
 negative
 coefficient
 of
 FOREIGNit
 will
 uphold
 the
 idea
 that
 immigrants
 and
 citizens
 are
 substitutes.
 2. Data
 This research uses data mainly drawn from the Current Population Survey.6 The
 CPS provides a variety of labor force statistics for the population of the United States.
 We extract our main variables such as income, educational attainment, and citizenship
 status from CPS. Information on the consumer price index (CPI) and gross domestic
 product (GDP) come from the World Bank.7 We also use the StateData.info website to
 collect data on U.S. state level unemployment rate.8
 Since
 we
 are
 testing
 the
 impacts
 of
 immigration
 on
 the
 US
 state--level
 income,
 the
 final
 sample
 for
 our
 empirical
 tests
 consists
 of
 data
 on
 51
 US
 states
 including
 the
 District
 of
 Columbia
 (DC).
 Our
 data
 set
 is
 strongly
 balanced
 and
 comprises
 16
 years
 from
 1995
 to
 2010.
 Table
 I
 presents
 descriptive
 statistics
 for
 our
 data
 set.
 Since
 we
 want
 to
 investigate
 the
 impact
 of
 immigration
 on
 the
 US
 citizens’
 income
 at
 the
 state
 level,
 we
 modify
 the
 CPS
 data
 set
 to
 fit
 our
 research
 purposes.
 To
 attain
 the
 data
 set
 including
 information
 on
 US
 citizens
 only,
 first,
 we
 separate
 the
 CPS
 data
 set
 into
 two
 groups,
 US
 citizens
 and
 non--citizens.
 From
 the
 individual
 observations,
 second,
 we
 get
 the
 average
 income
 per
 each
 state
 including
 DC
 for
 both
 US
 citizens
 and
 non--citizens.9
 Similarly,
 the
 average
 age
 variable
 per
 each
 state
 is
 obtained
 in
 the
 same
 way.
 6
 http://www.census.gov/cps/
 7
 http://data.worldbank.org/
 8
 http://www.statedata.info/
 9
 The
 average
 incomes
 are
 measured
 in
 constant
 2005
 dollars.
 Table
 I.
 Descriptive
 Statistics
 Variable
 Obs
 Mean
 Std.
 Dev.
 Min
 Max
 Y
 (Real
 Income)
 816
 41,845.56
 6376.732
 28393.09
 64327.52
 FOREIGN
 816
 218.8517
 410.5372
 5
 3,320
 GDP
 (M)
 816
 223,094
 270,254.3
 14,211
 1,768,607
 RATIO
 816
 .4360832
 .1544683
 .1972789
 1.683784
 UNEM
 816
 5.363603
 1.857371
 2.2
 14.9
 AGE
 816
 40.53957
 .9966217
 37.29797
 43.22313
 AGE2
 816
 1644.449
 80.60823
 1391.139
 1868.239
 Like
 our
 income
 variable
 (Y),
 The
 total
 number
 of
 foreign
 workers
 per
 state
 also
 comes
 from
 the
 CPS
 data
 set.
 We
 count
 the
 number
 of
 non--citizen
 individuals
 who
 are
 working
 in
 the
 US
 by
 states
 and
 year.
 Table
 II
 shows
 our
 sample
 number
 of
 non--citizen
 workers
 at
 the
 state
 level.
 Table
 II.
 The
 Number
 of
 Foreign
 Worker
 in
 2010
 State
 Foreign
 State
 Foreign
 State
 Foreign
 State
 Foreign
 AK
 131
 ID
 75
 MT
 23
 RI
 271
 AL
 50
 IL
 509
 NC
 202
 SC
 68
 AR
 57
 IN
 71
 ND
 21
 SD
 58
 AZ
 204
 KS
 103
 NE
 141
 TN
 89
 CA
 3,320
 KY
 93
 NH
 149
 TX
 1,185
 CO
 259
 LA
 46
 NJ
 645
 UT
 131
 CT
 384
 MA
 234
 NM
 106
 VA
 292
 DC
 278
 MD
 488
 NV
 386
 VT
 56
 DE
 169
 ME
 66
 NY
 1,092
 WA
 293
 FL
 938
 MI
 174
 OH
 107
 WI
 124
 GA
 268
 MN
 221
 OK
 84
 WV
 16
 HI
 353
 MO
 64
 OR
 173
 WY
 47
 IA
 166
 MS
 25
 PA
 157
 The
 CPS
 data
 set
 contains
 information
 on
 personal
 educational
 attainment.
 However
 it
 does
 not
 include
 information
 on
 the
 years
 of
 schooling.
 Educational
 attainments
 are
 originally
 classified
 by
 academic
 degrees
 such
 as
 high
 school
 diploma,
 associate
 degree,
 professional
 degree,
 and
 etc.
 Therefore,
 to
 quantify
 this
 information,
 we
 generate
 the
 RATIO
 variable
 which
 represents
 the
 quality
 of
 labor
 force
 for
 each
 states.
 Equation
 4
 displays
 how
 we
 generate
 the
 RATIO
 variable.
 (4)
 ?????????? = !h! !”#$%& !” !”#$%” !h! !”# ! !”#h!” !”#$”” !h!” !”#h !”h!!” !”#$%&’
 (!h! !”#$%& !” !”#$%” !h! !”# ! !”#h !”h!!” !”#$”” !” !”#$%)
 According
 to
 our
 calculation,
 the
 average
 value
 of
 the
 RATIO
 variable
 is
 around
 .44
 over
 the
 sample
 time
 period.
 It
 means
 that
 there
 are
 44
 high--skilled
 workers
 available
 per
 each
 100
 low--skilled
 workers.
 Table
 III
 shows
 the
 ratio
 in
 2010.
 Table
 III.
 The
 Ratio
 of
 High--Skilled
 and
 Low--Skilled
 US
 Citizens
 in
 2010
 State
 Ratio
 State
 Ratio
 State
 Ratio
 State
 Ratio
 AK
 .4
 ID
 .40
 MT
 .51
 RI
 .57
 AL
 .34
 IL
 .59
 NC
 .49
 SC
 .36
 AR
 .29
 IN
 .35
 ND
 .47
 SD
 .44
 AZ
 .44
 KS
 .54
 NE
 .56
 TN
 .43
 CA
 .61
 KY
 .39
 NH
 .65
 TX
 .43
 CO
 .80
 LA
 .42
 NJ
 .68
 UT
 .45
 CT
 .70
 MA
 .89
 NM
 .45
 VA
 .71
 DC
 1.68
 MD
 .75
 NV
 .33
 VT
 .60
 DE
 .46
 ME
 .52
 NY
 .65
 WA
 .56
 FL
 .51
 MI
 .47
 OH
 .37
 WI
 .50
 GA
 .55
 MN
 .54
 OK
 .38
 WV
 .38
 HI
 .46
 MO
 .36
 OR
 .54
 WY
 .34
 IA
 .39
 MS
 .28
 PA
 .47
 IV. Empirical Results
 The main purpose of this empirical study is to quantify the impact of non--citizen
 workers
 on
 US
 citizens’
 income.
 Our
 empirical
 results
 satisfy
 standard
 Mincer
 equation
 expectation.
 The
 empirical
 results
 are
 shown
 in
 Table
 IV.
 First
 three
 results
 are
 from
 the
 ordinary
 least
 squares
 (OLS)
 method.
 Regression
 IV.4
 shows
 the
 results
 of
 our
 model
 including
 state
 fixed
 effects
 and
 regression
 IV.5
 presents
 the
 results
 from
 random
 effects
 estimation.
 Regression
 IV.1
 contains
 only
 basic
 Mincer
 variables
 such
 as
 educational
 attainment
 of
 population
 (RATIO)
 and
 working
 experiences
 (AGE
 and
 AGE2).
 In
 addition
 to
 these
 variables,
 regression
 IV.2
 includes
 information
 on
 each
 states
 economy
 (UNEM)
 and
 national
 economy
 (GDP).
 Regression
 IV.3,
 IV.4,
 and
 IV.5
 contain
 all
 six
 independent
 variables,
 which
 accords
 with
 our
 equation
 (3).
 All
 coefficients
 on
 the
 RATIO
 variable
 are
 positive
 and
 statistically
 significant,
 which
 confirms
 that
 educational
 attainment
 is
 positively
 correlated
 with
 US
 citizens’
 income.
 Coefficients
 on
 AGE
 and
 AGE2
 variables
 also
 satisfy
 the
 theoretical
 prediction
 and
 coefficients
 on
 UNEM
 and
 the
 logarithm
 of
 the
 GDP
 variables
 empirically
 suggest
 that
 US
 citizens’
 income
 depends
 on
 the
 state
 and
 national
 economic
 situation.
 The
 coefficients
 on
 our
 key
 variable,
 the
 logarithm
 of
 the
 FOREIGN
 variable,
 turn
 out
 positive
 and
 statistically
 significant.
 It
 suggests
 that
 the
 number
 of
 non--citizen
 workers
 is
 positively
 correlated
 with
 US
 citizens’
 income.
 Since
 the
 coefficients
 on
 the
 logarithm
 of
 the
 FOREIGN
 variable
 are
 elasticities,
 we
 need
 to
 calculate
 the
 marginal
 effects
 of
 non--citizen
 workers
 on
 citizens’
 income
 to
 see
 the
 economic
 significance.
 In
 2010,
 there
 are
 approximately
 31.3
 million
 non--
 citizens
 living
 in
 the
 US
 and
 the
 nominal
 GDP
 per
 capita
 in
 the
 US
 is
 $48,387.10
 The
 coefficients
 on
 the
 logarithm
 of
 the
 FOREIGN
 variable
 have
 a
 range
 from
 0.011
 to
 0.046.
 Therefore
 if
 we
 increase
 the
 number
 of
 non--citizen
 workers
 by
 313,000
 which
 is
 1%
 point
 of
 the
 total
 number
 of
 non--citizen
 workers
 in
 2010,
 then,
 according
 to
 our
 model
 prediction,
 the
 nominal
 GDP
 per
 capita
 will
 increase
 by
 from
 10
 According
 to
 the
 Department
 of
 Homeland
 Security,
 there
 are
 19.7
 million
 legal
 residents
 and
 approximately
 11.6
 million
 illegal
 immigrants
 in
 2010.
 $5.32
 to
 $22.26.
 Since
 the
 number
 of
 foreign
 born
 living
 in
 the
 US
 increases
 approximately
 500,000
 annually,
 these
 additional
 non--citizen
 workers
 raise
 the
 nominal
 income
 of
 US
 citizens
 by
 from
 $8.5
 to
 $35.6
 in
 2010,
 which
 is
 negligible.
 Table
 IV.
 Immigration
 and
 Real
 Income
 ln(Real Income) IV.1 IV.2 IV.3 IV.4 IV.5
 RATIO 0.675 0.619 0.51 0.304 0.414
 (29.06)*** (31.05)*** (26.47)*** (6.10)*** (14.58)***
 AGE 0.416 0.085 0.155 0.304 0.547
 (2.06)** (0.49) (1.01) (2.34)** (4.95)***
 AGE2 -0.005 -0.001 -0.002 -0.004 -0.006
 (-1.94)* (-0.34) (-0.85) (-2.25)** (-4.72)***
 UNEM -0.006 -0.008 -0.007 -0.009
 (-3.66)*** (-5.51)*** (-6.91)*** (-7.84)***
 ln(GDP) 0.052 0.017 0.21 0.062
 (18.07)*** (4.94)*** (10.31)*** (7.60)***
 ln(FOREIGN) 0.046 0.011 0.026
 (14.65)** (2.06)** (6.41)***
 Constant 1.443 7.532 6.407 1.617 -1.925
 (0.35) (2.16)** (2.07)** (0.64) (-0.87)
 Observations 816 816 816 816 816
 R-squared 0.57 0.69 0.76 0.68
 F-statistic 358.77 366.62 421.83 271.10
 Wald ?2 1525.14
 Note: Figures in parentheses are t-statistics.
 ***Significant at 1%; **significant at 5%; *significant at 10%.
 To see the role of educational attainments of non-citizen workers in affecting
 citizens’ income, we separate non-citizen workers by two different groups: Skilled and
 Unskilled. Table V and VI display our empirical results. The L-FOREIGN variable
 represents the number of non-citizen workers who has a high school diploma or less
 while the H-FOREIGN variable indicates the number of non-citizen workers who has
 higher educational attainments than a high school diploma. The empirical results from
 OLS do not differ. Compare to regression V.1 which is the same regression as regression
 IV.3 in Table IV, the coefficients
 on
 the
 logarithm
 of
 the
 L--FOREIGN
 and
 H-FOREIGN
 variables do not show any significant differences. These results support that both skilled
 and unskilled non-citizen workers are complements to US citizens even though the
 economic impact is negligible. Regression V.5 contains F-RATIO variable representing
 the educational attainments of non-citizen workers. The mean value of the F-RATIO
 variable is .30, which means that there
 are
 30
 high--skilled
 workers
 available
 per
 each
 100
 low--skilled
 workers.
 The
 coefficient
 on
 the
 F-RATIO variable is positive but
 statistically not different from zero. In short, our empirical results from OLS suggest that
 there is no heterogeneity between skilled and unskilled non-citizen workers in affecting
 US citizens’ income.
 Table
 V.
 Non--Citizen
 Workers’
 Educational
 Attainments
 (OLS)
 ln(Real
 Income)
 V.1
 V.2
 V.3
 V.4
 V.5
 RATIO
 0.51
 0.531
 0.489
 0.497
 0.502
 (26.47)***
 (28.02)***
 (23.47)***
 (24.50)***
 (24.71)***
 AGE
 0.155
 0.128
 0.192
 0.165
 0.166
 (1.01)
 (0.83)
 (1.22)
 (1.08)
 (1.08)
 AGE2
 --0.002
 --0.001
 --0.002
 --0.002
 --0.002
 (--0.85)
 (--0.67)
 (--1.08)
 (--0.92)
 --(0.93)
 UNEM
 --0.008
 --0.008
 --0.008
 --0.008
 --0.008
 (--5.51)***
 (--5.33)***
 (--5.09)***
 (--5.51)***
 (--5.53)***
 ln(GDP)
 0.017
 0.021
 0.02
 0.016
 0.016
 (4.94)***
 (6.22)***
 (5.48)***
 (4.34)***
 (4.53)***
 ln(FOREIGN)
 0.046
 0.047
 (14.65)**
 (13.90)***
 ln(L--FOREIGN)
 0.04
 0.027
 (14.07)***
 (6.94)***
 ln(H--FOREIGN)
 0.043
 0.02
 (12.79)***
 (4.33)***
 F--RATIO
 0.028
 (1.22)
 Constant 6.407 6.922 5.767 6.283 6.197
 (2.07)** (2.22)** (1.81)* (2.03)** (2.00)**
 Observations 816 816 816 816 816
 R-squared 0.76 0.75 0.75 0.76 0.76
 Note: Figures in parentheses are t-statistics.
 ***Significant at 1%; **significant at 5%; *significant at 10%.
 Table VI contains results from the fixed effects estimator. Regression VI.1 is our
 benchmark in Table VI. Regression VI.1 is the same regression as IV.4 in Table IV,
 which is empirically most preferred result.11 Our empirical results from the fixed effects
 estimator do not support the heterogeneity between skilled and unskilled non-citizen
 workers neither. The
 coefficients
 on
 the
 logarithm
 of
 the
 L--FOREIGN
 variable
 are
 positive
 and
 statistically
 significant.
 Once
 again,
 however,
 the
 magnitude
 is
 way
 to
 small
 to
 consider.
 Meanwhile,
 The
 coefficients
 on
 the
 logarithm
 of
 the
 H--FOREIGN
 variable
 are
 also
 positive
 but,
 surprisingly,
 statistically
 not
 significant.
 In
 addition,
 the
 coefficient
 on
 the
 F--RATIO
 variable
 is
 statistically
 insignificant,
 too.
 These
 empirical
 results
 provide
 evidence,
 in
 contrast
 to
 previous
 findings,
 that
 it
 is
 not
 skilled
 immigrants
 but
 unskilled
 immigrants
 who
 are
 complements
 to
 US
 citizens
 even
 though
 the
 economic
 magnitude
 is
 small.
 Table
 VI.
 Non--Citizen
 Workers’
 Educational
 Attainments
 (Fixed
 Effects)
 ln(Real
 Income)
 VI.1
 VI.2
 VI.3
 VI.4
 VI.5
 RATIO
 0.304
 0.308
 0.307
 0.307
 0.304
 (6.10)***
 (6.12)***
 (6.21)***
 (6.10)***
 (6.09)***
 11
 The
 Lagrange
 Multiplier
 (LM)
 and
 the
 Hausman
 tests
 suggest
 that
 results
 from
 the
 fixed
 effects
 estimator
 are
 the
 most
 preferred
 results
 over
 OLS
 and
 the
 random
 effects
 estimator.
 AGE
 0.304
 0.294
 0.295
 0.296
 0.303
 (2.34)**
 (2.27)**
 (2.27)**
 (2.27)**
 (2.34)**
 AGE2
 --0.004
 --0.003
 --0.003
 --0.004
 --0.004
 (--2.25)**
 (--2.17)**
 (--2.18)**
 (--2.18)**
 (--2.24)**
 UNEM
 --0.007
 --0.007
 --0.006
 --0.007
 --0.007
 (--6.91)***
 (--6.84)***
 (--6.62)***
 (--6.91)***
 (--6.91)***
 ln(GDP)
 0.21
 0.212
 0.223
 0.212
 0.21
 (10.31)***
 (10.34)***
 (11.14)***
 (10.38)***
 (10.27)***
 ln(FOREIGN)
 0.011
 0.011
 (2.06)**
 (2.06)**
 ln(L--FOREIGN)
 0.01
 0.009
 (1.94)*
 (1.73)*
 ln(H--FOREIGN)
 0.004
 0.001
 (1.07)
 (0.17)
 F--RATIO
 --0.001
 (--0.07)
 Constant
 1.617
 1.788
 1.657
 1.762
 1.629
 (0.64)
 (0.71)
 (0.66)
 (0.7)
 (0.65)
 Observations
 816
 816
 816
 816
 816
 R--squared
 0.68
 0.68
 0.68
 0.68
 0.68
 Finally, we also test for the internal competition among non-citizen workers in the
 US. The dependent variable is now the state-level real income of non-citizen workers and
 we include the US--WORKERS
 variable
 indicating
 the
 number
 of
 US
 citizen
 workers
 in
 the
 model. The empirical results are shown in Table VII. Regression VII.1 and VII.2
 from OLS and regression VII.3, VII.4, and VII.5 are from the fixed effects estimator. The
 empirical results suggest that, first, there is no empirical evidence of the internal
 competition among non-citizen workers.12 Second, the coefficients on the logarithm
 of
 the
 US--WORKERS
 variable are positive and statistically significant, which supports,
 again, the complementarity between non-citizen workers and US citizens. Third, the real
 income of non-citizen workers mainly depends on state and national level of economic
 situations not their personal attributes.
 Table
 VII.
 Non--Citizen
 Workers’
 Income
 ln(F--Real
 Income)
 VII.1
 VII.2
 VII.3
 VII.4
 VII.5
 F--RATIO
 0.071
 0.067
 --0.173
 --0.168
 --0.173
 (1.26)
 (1.2)
 (--1.23)
 (--1.2)
 (--1.23)
 F--AGE
 0.107
 0.097
 0.028
 0.028
 0.028
 (4.99)***
 (4.51)***
 (0.6)
 (0.58)
 (0.59)
 F--AGE2
 --0.001
 --0.001
 0
 0
 0
 (--4.13)***
 (--3.72)***
 (0.44)
 (0.41)
 (0.42)
 UNEM
 --0.018
 --0.019
 --0.019
 --0.019
 --0.019
 (--4.68)***
 (--4.91)***
 (--3.96)***
 (--4.03)***
 (--3.95)***
 ln(GDP)
 0.032
 0.009
 0.202
 0.191
 0.196
 (4.68)***
 (0.97)
 (4.23)***
 (3.76)***
 (3.86)***
 ln(US--WORKERS)
 0.072
 0.051
 0.046
 (3.80)***
 (2.29)**
 (1.09)
 ln(FOREIGN)
 0.027
 0.005
 (1.26)
 (0.13)
 Constant
 7.349
 7.348
 6.825
 7.18
 6.911
 (17.72)***
 (17.87)***
 (7.64)***
 (7.15)***
 (6.66)***
 Observations
 816
 816
 816
 816
 816
 R--squared
 0.15
 0.17
 0.1
 0.1
 0.1
 12
 The
 coefficients
 on
 the
 logarithm
 of
 the
 FOREIGN
 variable
 are
 statistically
 significant.
 V. Conclusion
 Using the CPS data set, in this paper, we investigate the impact of non-citizen
 workers on US citizens’ state-level income. Our empirical findings suggest that first, noncitizen
 workers, immigrants, are complements to US citizens but their contribution on US
 citizens’ income is too small to consider. Second, there is no heterogeneity between
 skilled and unskilled non-citizen workers in affecting US citizens’ income. Third, there is
 no empirical evidence that there is internal competition among non-citizen workers in the
 US.
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