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Draft, June 2006
Sex and Migration: Who is the Tied Mover?
By
Johanna Astrom♣
Olle Westerlund♣♣
Abstract We study the effects of interregional migration on two-earner households’ gross earnings and on the relative income between married/cohabiting men and women. In particular, we examine the nexus between education level and the relative income gains between spouses. The empirical analysis is based on longitudinal data from Sweden and functional regional labour markets as regional entities. Using difference-in-differences propensity score matching it is found that migration generally in-creases total gross wage earnings of households and has no significant impact on the male/female earnings gap. We find that the pre-migration level of education is a key determinant of migration and the economic outcome, and to some extent also for the effect on income distribution within the house-hold. The positive average effect on household earnings is largely explained by the income gains among highly educated males. Females experience on average no significant income gain in absolute terms from migration. However, the female educational level seems to be positively correlated with the effect on earnings, although the effect appears to be small. The relative male/female educational level seems to affect the relative income gain between spouses in the anticipated direction. However, significant increase in the female share of household income is indicated only for the sample of highly educated females married/cohabitant with males having a lower level of education.
♣ Department of Economics, Umeå University, SE-901 87 Umeå, Sweden. E-mail: [email protected] ♣♣ Department of Economics, Umeå University, SE-901 87 Umeå, Sweden. E-mail: [email protected].
Introduction
Investments in human capital, for example in health, education, and migration, are important
events for individuals, households, and on the aggregate also for the society. In a reasonably
functioning economy, these investments are expected to increase welfare and, under certain
circumstances, also the productivity of labour. Potentially, they may also have substantial
effects on the income distribution among income earners in general as well as within
households. Investments in education and geographical mobility may provide opportunities to
reduce the income differences between males and females, but may as well reinforce existing
income differences by asymmetrical favouring the careers of one of the sexes.
Empirical economic research on migration has typically been oriented towards the
determinants of migration and, to a somewhat lesser degree, towards the effects on income
among singles or couples. Only a small fraction of the research on migration has been
purposed for the study of the effects on intra-household income distribution. To the best of
our knowledge, there is no previous study that examines the determinants of changes in
family income distribution among households who relocates to another geographical labour
market.
Cooke (2003) studies married couples in the US and finds that migration increases in the
husband’s income and leaves the wife’s income unchanged, which is in line with the results in
an early study from the US by Sandell (1977). Cooke finds that this applies even in cases
where the wife has greater earning potential than her husband. Smits (2001) uses data on
married couples in the Netherlands and finds negative effects of migration on earnings for
both spouses. It is also found that most long-distance moves seem to be undertaken for the
career of the males. Jacobsen and Levin (2000) study interstate migration in the US during the
1980’s and report income gains only for the sample of single women. For married couples,
they find that the economic outcome of migration is negative and they find no effects of
migration on the relative income between spouses. Nivalainen (2002) studies Finnish
households and finds that migration for the most part occurs due to the demands of the
husband’s career, resulting in the wives being tied migrants. Employment after migration is
examined in Nivalainen (2004). The results show that employment among the majority of
2
men is unaffected. However, some groups of migrating husbands have higher employment
probability after migration, while the women never realize positive returns in terms of
employment. Using data on stable two-earner households in Sweden, Axelsson and
Westerlund (1998) find that migration does not affect real disposable income. Also based on
Swedish data, Nilsson (2000) concludes that migration increases the intra-household income
gap within young dual-university graduate households.
This study examines the effects of migration on the households total gross wage earnings and
the relative income between married/cohabitating males and females. We devote special
attention to the nexus between education and the relative outcome of migration for the
spouses. The reason for this is that the educational level of spouses is a potential indicator of
bargaining power which plays a decisive role in modern theories of intra household income
distribution (Lundberg and Pollak, 1996, 2001). The relevance of studies within this field of
research is also underlined by related international trends, such as the increased number of
two earners households, increasing investments in education, the increased share of females
entering higher education, and increasing interest in the issue of gender equality.
The empirical analysis is based on longitudinal data from Sweden. We use a large sample of
individuals who were married or cohabitants prior to and after migration. The sample is
confined to stable couples, both spouses being employed prior to migration. Sweden provides
an excellent ground for exploring these questions because of the availability of data, and
because of an internationally high labour force participation rate among women. The
remainder of this paper unfolds as follows. The next section gives a brief reference to theories
of distribution within the family and family migration. Section III presents the data and
estimation strategy. Section IV gives the estimation results. The final section contains
conclusions and discussion.
3
II Income distribution within the family and migration
One of the most common theoretical framework in economic studies of migration is the
standard human capital model where individual utility varies across potential locations and
the single individual chooses to reside in the location that maximizes utility, given location
specific benefits and costs (including eventual costs for relocation). For the single decision
maker, the model provides straightforward implications. For families, the decision to invest in
migration is much more complex.
Early models of family behaviour, labelled as common preferences models, the consensus
model (Samuelson, 1956) and the altruist model (Becker, 1974), imply that family decisions
are consistent with maximising a single utility function. A common feature of the common
preference models is pooling of incomes, meaning that incomes of e.g. a husband and wife are
pooled and the allocation of expenditures is independent of the relative contribution of
husband and wife. This means that a given increase in income has the same effect on utility
and consumer demand irrespective of which of the spouses that brings home the bacon.
Empirical evidence is, however, generally not consistent with the income pooling assumption
and more recent bargain models of family decisions seem to provide a more credible
description of the migration decision than the common preferences models does (see e.g.
Lundberg and Pollak, 1996).
The decision to invest in migration for a two-earner household has to satisfy both spouses and
the optimal location for the family may not be the optimal location for any of the two spouses
if being single. When a spouse moves along with her partner even though the individual gain
from “family optimum” is lower than the gain from a “free optimum”, it is commonly
throughout the literature called tied migration. At the optimal location for the family, the total
family utility is maximized and the tied migrant has to receive enough compensation from the
partner to migrate and stay in the relationship (Mincer, 1978). Analogously, one spouse may
also be a tied stayer, receiving enough compensation from the other spouse to stay at the
present location and stay in the marriage. It is, of course, also possible that both spouses are
tied migrants or tied stayers.
4
In a bargaining model the individuals are assumed to maximize their individual utility and the
behaviour of the family are not only dependent on total family income (ceteris paribus) but
also on the determinants of the payoff in case of no agreement, the threat point (Lundberg and
Pollak, 1996). The threat point can be either external, e.g. divorce, or internal an inefficient
non-cooperative equilibrium within marriage. The most extreme threat point is, for most
couples, likely to be divorce where the threat point and the bargained outcome depend on
environmental factors such as the spouse’s possibilities and opportunities outside the
marriage. In everyday bargaining the internal threat point is more plausible. In this case the
family’s demands depend on who receive income within the marriage. The bargained
outcome will depend upon the utility at the threat point and the decisions of the family will
depend on who receives the higher income within the marriage. It is however reasonable to
assume that the allocation problem has an external threat point, if the spouses can not agree on
a residential location they separate or divorce.
In the human capital model, where a single utility function is maximized, it is assumed that
the tied mover will be compensated for the loss it suffers from migration. The cooperative
bargaining models assume that all agreements can be reinforced and that there is no restriction
on the agreements made within the family. However it is not very likely that the couple can
make binding agreements about future distribution of resources within the marriage.
Lundberg and Pollak (2001) illustrate a non-cooperative two-stage game where the location is
determined in the first stage and the distribution of resources between spouses in the second.
Given that the investment in human capital yield different returns for the two individuals, the
bargaining power in future bargaining will be affected and thereby the spouses possibilities to
claim family resources in the future. If it is impossible for the spouses to make binding
agreements about future transfers of resources, the allocation problem may have an inefficient
outcome. The spouses realize that their bargaining power will be altered and this can lead to
either an inefficient location or inefficient divorce. An inefficient location is characterized by
not maximizing the total income for the household. The tied spouse prefers a bigger piece of a
smaller pie and the leader prefers being married to the alternative of receiving a higher
income and being separated.
Thus, modern theories seem to accommodate empirical observations that are inconsistent with
the older common preferences / income pooling models, and they generate several interesting
5
and seemingly realistic implications. It appears, however, as extremely difficult to pursue
rigorous empirical tests of these models and we make no such aspiration.1 In fact, previous
studies perform tests of older models based on unrealistic assumptions. Still, previous
empirical results are valuable and interesting in many respects. This study is also of
explorative nature and adds, in our view, substantial contributions in relation to previous
empirical research within this field. The specific empirical questions to be addressed are:
- does migration yield an income gain for the household as a whole?
- does migration affect the relative income between spouses?
- how are changes in relative earnings related to potential proxies for bargaining power,
such as level of education and previous income?
Educational level is a good proxy for potential wage level and it is therefore reasonable to
think that it would affect the family’s location decision, and consequently also the returns
from migration for the male and the female. Moreover, the bargaining models suggest that
some of the covariates in empirical household models of migration and post-migration
income, may be perceived as indicators of bargaining power. As pointed out by Lundberg and
Pollak (2001), education and pre-migration income are two possible candidates in this respect.
1 Naturally, changes in wages or incomes do not translate into changes in utility by necessity. It is, for example, extremely difficult to incorporate indicators of compensating wage and income differentials into empirical models.
6
III Data and estimation
We use annual panel data from various official registers by the Swedish National Tax Board,
the National Labour Market Administration of Sweden, and Statistics Sweden. The sample
pertains to residents in Sweden who were married or cohabitants in stable household
constellations between 1997 and 2003. We have included couples where both spouses were
employed in 1997 and where there exits observations on the earnings 1997-2003. The final
sample includes 125 891 couples out of which 1 911 have migrated in 1998 or 1999.
Descriptive statistics
Table 1: Sample means. Stayers Movers Variable2
Females Males Females Males
Individual attributes: Gross wage earnings 1997 1345.98 2426.08 1184.83 2417.62 Gross wage earnings 2000 1610.80 2841.27 1474.71 3143.56 Gross wage earnings 2001 1690.11 2923.94 1612.84 3254.29 Gross wage earnings 2002 1764.26 2938.02 1700.33 3320.75 Gross wage earnings 2003 1819.99 2934.96 1797.11 3378.10
Age 35.55 37.43 33.22 34.87 Student 1997 .051 .015 .097 .063 Elementary school or Compulsory school .101 .169 .074 .085
2-year secondary school .398 .374 .224 .215 3-year secondary school .133 .122 .116 .119 <3 years of university .220 .173 .266 .223 ≥3 years of university .143 .151 .311 .319 Ph. D .003 .0118 .006 .036
Farming .011 .032 .004 .021 Manufacturing .108 .273 .077 .196
Construction .013 .108 .0131 .058 Retail .154 .238 .127 .193 Private sector .103 .143 .105 .166 Public sector .537 .171 .532 .301 Couple attributes Child(ren) .927 .927 829 .829 Small children .335 .335 .519 .519
Welfare benefit .0182 .0182 .0491 .0491 Migration history .031 .031 .268 .268 Regional attributes: Ln extacces -3.063 -3.063 -3.190 -3.190 Stockholm county .201 .201 .209 .209 South of Sweden .141 .141 .103 .103 Population 402 213 402 213 387 124 387 124 Number of observations: 123 980 123 980 1 911 1 911
2 Detailed definitions of the variables are given in the Appendix 1.
7
Generally, the descriptive statistics follow the expected pattern. The movers have lower
earnings in 1997, they are on average younger and they have higher education than the
stayers. The females in the moving couples have a smaller wife/husband earnings ratio and it
has decreased slightly between 1997 and 2000 from 33 to 32 percent. The women in the non
moving couples, on the other hand, have increased their share of total household earnings
between 1997 and 2000.
Estimation
Migration can be perceived as a treatment as compared to the non-treatment alternative of
staying. The potential outcomes are Y1 for migration and Y0 for staying. For each individual,
there is a pair of outcomes of which only one can be observed. The parameter of main interest
is, in this case, the one which measures the average treatment effect on the treated, ATT =
E[Y1 - Y0 | M = 1], where M equals one for migration and zero for non-migration. Clearly E[Y0
| M = 1] can not be observed, i.e., what would have happened to the migrants had they not
moved. The outcomes of a sample of stayers generally serve as an estimate for the
counterfactual outcome. A well known problem with non-experimental data is that the
individuals who are subject of a treatment may be self selected into the treatment group.
Consequently, the estimated effect of treatment can be biased if the selection mechanism is
correlated with the outcome, e.g. migrants may have attributes making them more mobile and
more productive in any location.
In the present study, we use the method of difference-in-difference propensity score matching
to estimate the effect of migration on household incomes and relative incomes between
spouses. This method takes selection on observed attributes into account and eliminates
potential bias because of time-invariant unobserved heterogeneity.
Propensity score matching relies on the assumption that, conditional on some observable
characteristics X, outcomes are independent of the assignment to treatment. Given this
Conditional Independence Assumption, Rosenbaum and Rubin (1983) show that it also holds
for some function of X, that is,
)(|0 XpMY ⊥
8
where p(X) is the so-called propensity score, the probability that M = 1. The matching
procedure is then reduced to matching on a scalar, which means that the loss of a large
number of observations is avoided. A condition of common support is added, which is p(X) <
1 when ATT is the parameter of interest. It guarantees the possibility of a non-treated match
for each treated individual. The propensity score may be estimated, for example, by binomial
logit or probit.
By using information about the outcome variable before treatment it is possible to eliminate
potential bias due to time-invariant heterogeneity. Smith and Todd (2005) find that difference-
in-differences propensity score matching estimates are substantially less biased than cross-
sectional matching estimates. The difference-in-differences estimator can be written Y1 - Y0 =
(Y1t+i – Y1t) – (Y0t+i – Y0t), where the subscripts t and t+i denote periods of time before and after
migration.3
We have a large comparison group, which we exploit when constructing our counterfactuals.
By using more than one individual as a counterfactual, the bias may increase but the variance
reduces. When the propensity scores are asymmetrically distributed a kernel based procedure
is beneficial since it only uses the additional observations where they actually exist. The
kernel based procedure matches the migrant with “comparable” individuals among the
stayers. Assuming a migrant with outcome Yi and propensity score pi, kernel matching
constructs its counterfactual outcome, , from non-treated with piY j within a predetermined
bandwidth h of pi, and attaches more importance to closer matches. Given that | pi – pj | < h,
the matched outcome is given by iY
{ }
{ }∑
∑
=∈
=∈
⎟⎟⎠
⎞⎜⎜⎝
⎛ −
⎟⎟⎠
⎞⎜⎜⎝
⎛ −
=
0
0ˆ
Dj
ji
Djj
ji
i
hpp
K
yh
ppK
Y
3 The method of matching avoids the functional form restrictions of, for example, ordinary least squares (OLS) and also offers flexibility as counterfactual outcomes are calculated for each treated individual. OLS- regression techniques impose greater weight to the treatment effects at values of X which occur often and where the variance in M is larger. Given heterogeneous treatment effects, the OLS estimator does not correspond to ATT, and as pointed out by Angrist (1998), it is not necessarily an interesting estimate for an economic researcher.
9
where the weights of the kernel K sum to one.4 The purpose of the matching procedure is to
balance the covariates between migrants and non-migrants, to make the distribution of the
counterfactual outcome of staying the same as for the group of migrants. The estimated effect
of migration is the observed average difference between the outcomes of the migrants and
non-migrants in the matched sample.
The outcome variable in our main approach is constructed as [WE1997+i - WE1997] where WE
denote real annual wage earnings, and i is between three and six, i.e, we estimate the effect
after one, two, three and four years following the move from one labour market area to
another, where the move takes place in 1998 or 1999. We do this to distinguish eventual
differences between the immediate effects from the effects over a couple of years.
We also examine the effect of migration on the change in the female’s share of total
household earnings, this variable is constructed as ( ) ( )MF
F
Mi
Fi
Fi
WEWEWE
WEWEWE
19971997
1997
19971997
1997
+−
+ ++
+ . This is
also estimated after one, two, three and four years following the move.
As stated previously, propensity score matching takes observed heterogeneity into account.
The specification of the outcome as the difference-in-differences eliminates bias due to time
invariant unobserved heterogeneity affecting the individual’s gross wage earnings. It should
be noted that we take advantage of rich information on individual characteristics and
characteristics of the household. This should at least reduce the potential impact of the
remaining unobserved heterogeneity.
4 The weight of each (untreated) yj is { }∑
=∈⎟⎟⎠
⎞⎜⎜⎝
⎛ −⎟⎟⎠
⎞⎜⎜⎝
⎛ −
0Dj
jiji
hpp
Kh
ppK .
10
IV Results
The covariates in the estimation of the propensity score should have a causal effect on both
the probability to move and on the change in income. A large number of attributes that
according to theory and previous research may affect both the probability to move and the
change in earnings have been tested in the specification of the propensity score.5 First we
estimate logit equations to see which covariates influenced the probability to move. Secondly
we run regressions to see whether the variables from the first stage affects the difference in
earnings and difference in female earnings share between 1997 and 2000, 2001, 2002, 2003.
The same set of variables is used in the estimations for all sub-samples. Separate tests for each
sub-sample indicate that the matched samples are well balanced with respect to the included
covariates.
The kernel matching estimates of ATT for the whole sample are given in Table 2. The results
indicate a positive average effect on post migration gross wage earnings for the household as
a whole of about 20 500 SEK four years after the move, around 18 000 for males, and
approximately 2 500 for females.6
The estimated gains for females are, however, not significant. For the whole sample, there
seems to be positive returns from migration for both men and women both instantly and a few
years later.
5 Specification of the propensity scores is given in Appendix 2.The propensity scores have been estimated for the entire sample and conditioned on the educational level of the spouses separately. This allows for different parameter specifications by education. 6 The share of the movers/stayers that are in higher education in 2000 are 3.7/1.4 for men and 9.5/7.5 for women. The share that have taken parental leave in 2000 are 46.9/38.9 for men and 63.5/55.0 for women. When controlling for age, a substantial part of these differences disappear. We expect that when controlling for educational level and other covariates that this difference becomes even smaller. This should not influence our results.
11
Table 2; Propensity score matching estimates of the effect of migration on gross wage earnings (100 SEK), standard errors within parentheses7.
Outcome Females Males Household WE2000-WE1997 -4.10
(24.34)
123.06*** (51.92)
118.97** (57.76)
WE2001-WE1997 28.62 (25.72)
86.96* (47.35)
115.58** (54.77)
WE2002-WE1997 14.10 (28.32)
123.40*** (47.40)
137.49*** (56.13)
WE2003-WE1997 24.02 (29.62)
181.09*** (48.64)
205.11*** (58.01)
Number of couples (Movers): 125,891 (1,911)
Note: The estimates are based on the Normal kernel with bandwidth .001 and a common support restriction. Five per cent of the moving observations are trimmed where the propensity-score density of the control observations are the lowest.
To see whether these results hold when controlling for the educational level of the spouses, a
potential indicator of bargaining power, we have carried out separate estimations for different
educational combinations within the couples, table 3 and 4. If the individual has university
education he/she is labelled as having a high level of education. If not; the individual has a
low level of education.
Table 3 reads as follows; the estimated effect between 1997 and 2000 for a female having low
education living with a male having low education is a reduction in earnings of about 8200
SEK, point estimate equals -82.13 with a standard error of 37.07. If the female having low
education lives with a male that has high education her loss in earnings between 1997 and
2000 is 1300 SEK, point estimate equals -13.28. For a male having low education living with
a female having low education the estimated decrease in earnings between in 1997 an 2000 is
1 900 SEK, point estimate equals -19.23. A male having high education living with a female
having low education the estimated effect on earnings between 1997 and 2000 is an increase
of 37 700 SEK, point estimate is 377.13.
7 In large samples there is evidence that the component of the variance from the estimation of the propensity scores can be disregarded (Eichler and Lechner, 2002). The standard errors are computed as;
nTTVarTT )()( =σ
12
Table 3; Propensity score matching estimates of the effect of migration on gross wage earnings, conditional on the female having low education, standard errors within parentheses. Outcome Females Males Household Male’s education
Low/ High Male’s education
Low/ High Male’s education
Low/ High WE2000-WE1997 -82.13** / -13.28
(37.07 / 58.30)
-19.23 / 377.13* (48.70 / 220.69)
-101.36 / 363.85 (65.45 / 223.59)
WE2001-WE1997 -32.71 / 33.96 (38.82 / 62.37)
-3.28 / 616.31*** (54.46 / 250.58)
-36.00 / 650.28*** (70.84 / 256.10)
WE2002-WE1997 -49.75 / -33.18 (41.84 / 67.94)
10.86 / 587.74*** (58.89 / 229.77)
-38.89 / 554.56*** (77.99 / 236.53)
WE2003-WE1997 -67.10 / -66.71 (43.21 / 65.96)
3.33 / 571.47*** (63.52 / 228.84)
-63.77 / 504.76** (82.70 / 230.95)
Number of couples (Movers): 63,912 (556)/ 15,403 (239)
Note: The estimates are based on the Normal kernel with bandwidth .001 and a common support restriction. Five per cent of the moving observations are trimmed where the propensity-score density of the control observations are the lowest. *, **, *** significant at the 10, 5, 1 percent level.
If the female have a low level of education in 1997, the returns from migration for the
household as a whole differs regarding the educational level of the male (Third column in
Table 3). A couple where both spouses have low education experiences no monetary gain.
The estimates are negative and the estimated standard errors are relatively large. A couple
where the male have a high level of education and the female does not, receives the highest
estimated return from migration for the household as a whole (about 50 000), and the male
earnings growth of 57 000 dominates the estimated female earnings reduction of nearly 7 000.
Again, the standard errors are rather large and only the estimates of the male’s gains and total
household earnings are statistically significant.
Table 4 presents the results conditional on the female having university education. The
estimated effect from migration on total household earnings is positive regardless of the
educational level of the male, but it is only significant when both have a high level education.
The female’s return is about the same for high and low levels of their husband education. It
seems as it is the educational level of the husband that primarily determines the outcome on
13
Table 4; Propensity score matching estimates of the effect of migration on gross wage earnings, conditional on the female having high education. Standard errors within parentheses.
Outcome Females Males Household
Male’s education Low/ High
Male’s education Low/ High
Male’s education Low/ High
WE2000-WE1997
65.88/ 41.31 (72.23/ 39.89)
-1.66/ 217.30*** (88.23/ 86.91)
64.23/ 258.61*** (109.39/ 96.12)
WE2001-WE1997
126.53/34.01 (77.79/ 42.32)
-84.27/ 79.28 (94.04/ 62.16)
42.26/ 113.28 (127.03/ 76.68)
WE2002-WE1997
73.78/ 35.87 (77.92/ 47.74)
-24.43/ 140.52** (120.94/ 63.50)
49.35/ 176.39** (140.36/ 80.64)
WE2003-WE1997
60.15/ 101.31** (83.23/ 50.66)
-39.47/ 274.07** (117.59/ 66.26)
20.68/ 375.37*** (141.52/ 84.84)
Number of couples (Movers): 19,200 (251)/ 27,376 (865)
Note: The estimates are based on the Normal kernel with bandwidth .001 and a common support restriction. Five per cent of the moving observations are trimmed where the propensity-score density of the control observations are the lowest. *, **, *** significant at the 10, 5, 1 percent level.
total household earnings. A couple where both spouses have higher education the total
household gain from migration after four years is about 38 000, where of the major part
derives from the effect on the earnings of the male.
The monetary benefit for a male with higher education appears to be dependent on the
educational level of his spouse. A highly educated male living with a highly educated female
receives an increase in earnings that is substantially lower than for those living with low
educated females (27 000 compared to 57 000 four years after the move). For males and
females with a low level of education, the effect on individual earnings is slightly negative or
zero, and the educational level of the spouse does not seem to matter for the size of the return
from migration.
Does migration affect the female share of household income? Table 5 gives the matching
estimates of the effect on females share between 1997 and post-migration shares measured
14
each year from 2000 to 2003. When using the whole sample (first column in Table 5), the
estimated effect from migration is positive but insignificant in three cases out of four. When
the sample is separated by educational level, all estimates pertaining to females with a low
Table 5; Propensity score matching estimates of the effect of migration on the female’s share of total household gross wage earnings, standard errors within parentheses.
Outcome Entire sample
Female low and male low/high
education
Female high and male low/high
education
( ) ( )MF
F
MF
F
WEWEWE
WEWEWE
19971997
1997
20002000
2000
+−
+ .0008
(.0061)
-.0063/-.0061 (.0130/ .0170)
.0347*/ -.0050 (.0185/ .0079)
( ) ( )MF
F
MF
F
WEWEWE
WEWEWE
19971997
1997
20012001
2001
+−
+ .0126 **
(.0064)
.0196/-.0056 (.0134/ .0177)
.0432***/ -.0029 (.0180/ .0085)
( ) ( )MF
F
MF
F
WEWEWE
WEWEWE
19971997
1997
20022002
2002
+−
+ .0025
(.0064) .0019/-.0192
(.0129/ .0177)
.0345*/ -.0065 (.0192/ .0085)
( ) ( )MF
F
MF
F
WEWEWE
WEWEWE
19971997
1997
20032003
2003
+−
+ .0052
(.0066) .0087/-.0181
(.0139/ .0200)
.0347*/ -.0027 (.0195/ .0086)
Number of couples (movers) 125 891 (1 911)
63 912 (556)/ 15,392 (228)
19,188 (239) / 27,333 (822)
Note: The estimates are based on the Normal kernel with bandwidth .001 and a common support restriction. Five per cent of the moving observations are trimmed where the propensity-score density of the control observations are the lowest. *, **, *** significant at the 10, 5, 1 percent level.
level of education are insignificant (second column in Table 5). However, for the sample of
highly educated females married/cohabiting with males having a lower level of education, the
estimates are positive and significant in all four cases (left entries in the third column). For
this sample, the migration seems to increase the female share of total household earnings
around four percentage points. Although most of the estimates in table 5 are not significant,
they are generally in accordance with the hypothesis that spouses education matters for the
effect of migration on the female/male relative share of total household income. There is,
however, no evidence of substantial effects of education on the impact of migration on
females/males relative earnings, except for the sample of highly educated females whose
partners have a low level of education.
To separate the hypothetical effects from education and income on bargaining power, we split
the sample according to whom of the spouses that had higher average earnings over the three
15
years prior to the move (table 6 and 7). For the sample of households with the male as the
principal earner (Table 6), his spouse was the relative winner. The estimated effects of the
change in female share are significant between years of 1997 and 2001, 2002 and 2003 (first
column table 6). The estimates of the change in the female share are positive for all but one
combination of educational levels. The estimates are, however, only significant if the male
has low education. Judging from these estimates, males with low levels of education
experience the largest loss in relative income. There is, nevertheless, no clear cut pattern
indicating that the relative level of education determines the changes in income shares. Given
that the male has a low level of education (left entries in columns 2 and 3 in table 6), the
relative gain for females with a low level of education is close to the estimated gain for
females with a higher education.
Table 6; Propensity score matching estimates of the effect of migration on the female’s share of total household gross wage earnings, conditional on the woman’s share being less than 0.5 in 1995-1997. Standard errors within parentheses.
Outcome Entire sample
Female low and male low/high
education
Female high and male low/high
education
( ) ( )MF
F
MF
F
WEWEWE
WEWEWE
19971997
1997
20002000
2000
+−
+
.0072 (.0059)
.0134/ -.0111 (.0132/.0157)
.0292/.0032 (.0190/.0075)
( ) ( )MF
F
MF
F
WEWEWE
WEWEWE
19971997
1997
20012001
2001
+−
+
.0185** (.0061)
.0380***/ -.0025 (.0135/.0157)
.0285/.0112 (.0192/.0080)
( ) ( )MF
F
MF
F
WEWEWE
WEWEWE
19971997
1997
20022002
2002
+−
+
.0112* (.0062)
.0174/ -.0160 (.0129/.0163)
.0419**/.0072 (.0211/.0082)
( ) ( )MF
F
MF
F
WEWEWE
WEWEWE
19971997
1997
20032003
2003
+−
+
.0147** (.0064)
.0197/ -.0045 (.0144/.0172)
.0389*/.0095 (.0202/.0083)
Number of couples (movers) 104 581 (1 522)
52,686 (413)/ 13,925 (203)
14,904 (187)/ 23,336 (719)
Note: The estimates are based on the Normal kernel with bandwidth .001 and a common support restriction. Five per cent of the moving observations are trimmed where the propensity-score density of the control observations are the lowest. *, **, *** significant at the 10, 5, 1 percent level.
In couples where the male was the secondary earner the preceding years (table 7), reallocation
increases his relative share of total earnings. This result holds for all educational combinations
except one. In couples where the female has higher education than the male, she experiences a
larger effect on her earnings than her partner does.
16
In all, we find that the secondary earner receives an increase in the share of total household
earnings as a result of migration. This applies for both sexes, although this effect seems to be
smaller for females than males on average when comparing the first columns in tables 6 and
7. Moreover, in couples where the female has a high level of education and the male does not,
migration increases the female share of household income whether or not she is the principal
earner before migration. Without jumping to conclusions, the results seem to indicate that
initial income is not positively correlated with bargaining power affecting the relative
earnings outcomes from migration.
Table 7; Propensity score matching estimates of the effect of migration on the female’s share of total household gross wage earnings, conditional on the female’s share being equal to or more than 0.5 in 1995-1997. Standard errors within parentheses.
Outcome Entire sample
Female low and male low/high
education
Female high and male low/high
education
( ) ( )MF
F
MF
F
WEWEWE
WEWEWE
19971997
1997
20002000
2000
+−
+
-.0381** (.0170)
-.0494/.0148 (.0309/ .0655)
.0712/ -.0563*** (.0527/.0242)
( ) ( )MF
F
MF
F
WEWEWE
WEWEWE
19971997
1997
20012001
2001
+−
+
-.0341* (.0177)
-.0257/-.0180 (.0313/.0694)
.0943/ -.0753*** (.0485/.0266)
( ) ( )MF
F
MF
F
WEWEWE
WEWEWE
19971997
1997
20022002
2002
+−
+
-.0430*** (.0168)
-.0330/-.0322 (.0307/.0702)
.0506/ -.0667*** (.0449/.0258)
( ) ( )MF
F
MF
F
WEWEWE
WEWEWE
19971997
1997
20032003
2003
+−
+
-.0408** (.0177)
-.0254/-.0891 (.0318/.0753)
.0497/ -.0624*** (.0533/.0249)
Number of couples (movers) 21,040 (389) 11,226 (143)/ 1,478 (36)
3,765 (64)/ 4,040 (146)
Note: The estimates are based on the Normal kernel with bandwidth .001 and a common support restriction. Five per cent of the moving observations are trimmed where the propensity-score density of the control observations are the lowest. *, **, *** significant at the 10, 5, 1 percent level.
Summing up the empirical results, our findings indicate that migration affects earnings
positively for the household. However, this applies only for households where the male has a
high level of education. Another finding is that the spouse with the highest level of education
seems to be the relative winner from migration, although this is only significant when the
female has a higher level of education. When the male and the female have unequal levels of
education, the spouse with the lower level of education experience no gain in earnings from
migration.
17
V Conclusion and discussion
Our findings indicate that migration has a positive effect on total household gross wage
earnings. The average effect derives primarily from the large earnings increases among highly
educated males. In general, we find little evidence of positive effects of migration on earnings
among females. However, the education level seems to be positively correlated with the
income gain also among the females, although the estimated effects are relatively small or
statistically insignificant even for the highly educated females.
When examining the change in the female/male share of total household earnings, we find
that the effect of migration is negligible on average. The relative educational level between
spouses does, however, matter for the effect of migration on relative earnings within the
household. Highly educated females coupled with low educated males, experience an increase
in the income share of around four percentage points compared to non-migrants. The largest
negative effect of migration on the female earnings share is found among females with a low
level of education whose male partners are highly educated.
Although not conclusive evidence, we interpret our empirical findings in relation to the
concept of tied migration as follows. The substantial gain in total income among migrating
two-earner households implies that migration ties are not important enough to fully offset
increases in household income as a result of migration. Moreover, tied migration does not
counteract potential income gains to an extent that incurs a decrease in income for the male or
the female. This applies on average for the whole sample.
Disaggregated analysis reveal that education levels affect the gains from migration in terms of
individual earnings, total household earnings and the female share of total earnings. The latter
finding is, however, statistically and economically important only for highly educated females
married/cohabitating with males having a lower level of education. A cautious interpretation
of the results is that they do not speak against the hypotheses that the relative education level
between spouses matters for bargaining power when household location decisions are made.
Being the principal income earner seems not to yield decisive intra-household bargaining
18
power in this context. Our findings indicate that the spouse with the lower income experience
the largest effect of migration on the relative share of total household income.
19
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21
Appendix 1 Individual attributes: Gross wage earnings 1997-2003; in hundreds of Swedish Kronor. Age; in 1997. Child(ren); couple has at least one child below the age of 18 living at home. Small children; couple only has children under the age of seven living at home. Student; individual received study aid for higher education or adult education. Educational level; highest level of education attained by 1997. Sector; sector of work in 1997 according to the Industry code (sni92) as defined by Statistics Sweden. Welfare benefit; family received benefit in 1997. Migration history at least one of the spouses has moved between 1994 and 1997. Regional attributes: Ln extacces; Stockholm; couple lived in Stockholm county in 1997. South of Sweden; couple lived in Skåne or Blekinge county in 1997. Population; total population aged 16-64 in labour market region in 1997.
22
Appendix 2 Variable Logit estimation of migration in
1998 or 1999 Regression on difference in total
household gross income 1997-2000
lnextacc -0,00472 (-1,49)
1,346856 (1,17)
*
befolk97 -4,35E-07 (-5,85)
*** 0,000475 (26,13)
***
reg4dm7 -0,32588 (-4,21)
*** -110,35 (-6,92)
***
lder7 -0,04721 (-8,71)
*** -4,12401 (-3,19)
***
barn97 -0,78396 (-9,7)
*** 564,6162 (25,64)
***
student 0,62409 (5,8)
*** 327,256 (7,35)
***
studentf 0,393793 (4,69)
*** 358,6813 (14,28)
***
social 1,161118 (9,63)
*** -9,87586 (-0,24)
smbarn 0,587022 (9,4)
*** 185,164 (13,1)
***
mig9497 1,736851 (29,14)
*** 35,82998 (1,15)
utbild_3 -0,05596 (-0,59)
1,463503 (0,09)
utbild_4 0,328472 (3,07)
** 130,4683 (6,1)
***
utbild567 0,586044 (6,22)
*** 460,9587 (24,68)
***
utbildf_3 -0,27715 (-2,72)
** 37,43335 (1,89)
*
utbildf_4 -0,1938 (-1,69)
* 148,7138 (6,25)
***
utbild567f 0,184831 (1,83)
* 347,2571 (16,43)
***
sektor_2 -0,27947 (-1,68)
* -169,121 (-5,13)
***
sektor_3 -0,43196 (-6,66)
*** -28,0523 (-1,87)
*
sektor_4 -0,48265 (-4,58)
*** -77,538 (-3,85)
***
sektor_5 -0,2196 (-3,34)
*** 11,70188 (0,76)
_cons -2,1681 (-9,25)
*** -259,193 (-4,43)
***
Note: *** Indicates significant at the 1 percent level; ** indicates significant at the 5 percent level and * indicates significant at the 10 percent level.
23