Discussion Paper Series

University of Tokyo

Institute of Social Science
Panel Survey
東京大学社会科学研究所 パネル調査プロジェクト
ディスカッションペーパーシリーズ

Educational Assortative Mating in Japanand the United States

Hiroshi Ishida（Institute of Social Sciences, University of Tokyo）

Akira Motegi（Institute of Social Sciences, University of Tokyo）

September 2012
No.62

INSTITUTE OF SOCIAL SCIENCE

東京大学社会科学研究所
UNIVERSITY OF TOKYOInstitute of Social Sciences
University of Tokyo
Panel Survey Project Discussion Paper Series No. 62
September, 2012

Educational Assortative Mating in Japan and the United States

Hiroshi Ishida(Institute of Social Sciences, University of Tokyo)
andAkira Motegi(Institute of Social Sciences, University of Tokyo)

The permission to use the panel data is obtained from the Research Planning Committeeof the Japanese Life Course Panel Surveys. This research was supported by
Grant-in-Aid for Scientific Research (S) (numbers 18103003 and 22223005) from theJapan Society for the Promotion of Science (JSPS). The research support in conducting
the panel surveys from the Institute of Social Science, University of Tokyo, and theOutsourcing Company is gratefully acknowledged. The authors are grateful to Shin
Arita, Satoshi Miwa, and Koji Yamamot for helpful comments.

Educational Assortative Mating in Japan and the United States
Hiroshi Ishida(Institute of Social Sciences, University of Tokyo)
andAkira Motegi(Institute of Social Sciences, University of Tokyo)

Abstract
We investigate different patterns of educational assortative mating between Japan andthe United States. Unlike the conventional approach which exclusively looks atmarried couples, we take a promising alternative one to include unmarried couples in
the analysis and to compare the patterns of educational assortative mating acrossdifferent partnership statuses. To highlight the distinctive patterns of Japanese couples,
we provide the comparison between the case of Japan and that of the United States
The log-linear model analysis with the JLPS for Japanese couples and the NSFG for
couples in the United States gave the following results. For the case of Japan, we
found the significant difference in the pattern of educational assortative mating between
married and unmarried couples, which is characterized as a stronger educational
homogamy among married couples who graduated from college than among unmarriedcollege-educated couples and as a propensity for women with junior college education
to marry with men of college education. The result for the United States shows adifferent fabric. We found a clear propensity to find partners with the same level of
education at the top and at the bottom of educational hierarchy, but the magnitude of thepropensity does not vary across three types of couples: dating, cohabitation and married
couples. Some discussions and speculations based on these findings are drawn for theunderstanding of the transition from courtship to marriage in Japan.
Keywords: educational assortative mating, marriage, courtship1. INTRODUCTION
We investigate patterns of educational assortative mating in Japan and the United States.
Couples, whether married or unmarried, are formed on the basis of matching on avariety of socioeconomic and cultural characteristics, shaping a distinct pattern ofassortative mating. The resemblances or differences between matched couples reflect
the extent of closure or openness in our society, a longstanding concern for sociologists(Blossfeld 2009). Among the various factors couples take into account, education is oneof the most well-established measures in assortative mating (Blossfeld 2008, Miwa
2005, Schwartz and Mare 2005).
The conventional approach taken by many previous studies targeted at married couples
as the primary focus of the analysis. The main research question concerns educational
assortative mating among married couples: who marries whom1. However, the past
decades have seen the tremendous increase of cohabitation among unmarried couples in
the United States and European countries, a well-documented fact which motivatedresearchers to look at the difference in the pattern of assortative mating between married
couples and unmarried couples. Recent progress in data gathering on unmarried couples
led to this new development, particularly in the United States. Thus, researchers can
now reframe the research question as follows: who mates with whom among dating,cohabitating, and married couples2.
On the other hand, it is often pointed out that Japanese society has not experienced thedramatic increase of cohabitation as observed in the United States or Europe. However,unmarried couples and courtship (as a partnership status) are no longer uncommon incontemporary Japan. Today most of marriages are formed as love-marriage (ren-ai
kekkon)3., implying that many married couples must have experienced courtship state
Blossfeld (2009) provides an extensive review of the literature from a cross-country
perspective. For examples of previous analyses on Japanese couples, see Miwa (2005),
Shida et al. (2000) and Shirahase (1999).
2
Schwartz (2010, p. 736-738) provides a concise summary of recent developments inthe comparative investigation between married and unmarried cohabitating couples.
Blackwell and Lichter (2004) classify three partnership statuses, i.e., "dating,"
cohabitating," and "married" couples. We employ the same three categories for the
analysis of American data set.
3
Based on the calculations from the 13th Japanese National Fertility Survey conducted
in 2005, the National Institute of Population and Social Security Research (2007, p.18)
reports that 86.8% of the married couples in the survey formed their marriage as
1

1

prior to marriage. Despite the lack of prevalence of cohabitation, courtship has
become an important life stage for Japanese youth. We therefore examine the topic ofassortative mating by expanding our scope to include unmarried couples into theanalysis of Japanese data. To our knowledge, there is no previous research which
distinguishes the patterns of educational assortative mating between married andunmarried couples in Japan. Our paper presents the first systematic account on this
topic.
Moreover, comparison between Japanese married and unmarried couples will contributeto our understanding of marriage behavior in Japan. Courtship behavior of unmarried
couples including the pattern of assortative mating is one of the most under-explored
topics in Japanese sociological studies in general and marriage studies in particular,
despite the potential importance of its role as the transitory state leading to marriage.
Our explicit distinction of couples by partnership status will highlight the difference
between the types of couples and the relationship between courtship and marriage. We
will provide the comparison with the United States in order to highlight the distinct
patterns of Japanese couples.
The next section explains the datasets and methods used in our analysis. The third
section reports the results of our analyses for Japan and the United States. The final
section summarizes the main findings and discusses some implications of thedifferences in the pattern of educational assortative mating between the two nations.
2. DATA AND METHODSTo characterize distinct patterns of educational assortative mating, we use datasets
which allow us to specify educational levels of both marital and non-marital couples.
We use the Japanese Life Course Panel Survey (JLPS) for Japanese couples4. The JLPS
is a nationally representative panel survey conducted annually by the Center for Social
Research and Data Archives at the University of Tokyo. The sample design included
men and women between the ages of 20 to 34 (youth sample) and 35 to 40 (middle-agedlove-marriage.
4
We gratefully acknowledge the support of the Grant-in-Aid for Scientific Research(S)（number 18103003 and 22223005) from the Japan Society for the Promotion of
Science (JSPS) and research support from the Institute of Social Science, University ofTokyo, and Outsourcing, Inc. in conducting the panel surveys. The permission to use thepanel data is obtained from the Research Planning Committee of the JLPS.
2

sample) living Japan in 2007. We use the information collected in wave 1 (2007)
through wave 5 (2011) when the respondents were 24 to 44.
The data for couples in the United States come from the National Survey of Family
Growth (NSFG). The NSFG is a nationally representative survey conducted by the
National Center for Health Statistics for the U.S. Department of Health and Human
Services. The survey is cross-sectional in design but conducted periodically. The sample
design included men and women in the United States between the ages of 15 to 45
during the survey period. We use the 2006-2010 survey which was conducted from June
2006 to June 2010. 5
We differentiate two partnership statuses for couples in Japan and three for couples in
the United States. For Japanese couples, we consider two kinds of status: dating
couple in which both partner are unmarried at the time of survey and married couple.
Three kinds of status are distinguished for the couples in the United States. The firststatus is unmarried and dating couple (denoted by "dating couple" hereafter); second isunmarried cohabitating couple (called "cohabitating couple"); and third is married
couple. Cohabiting couples are classified as a separate category because they form
more stable partnership than dating couples and constitute a substantial portion of the
distribution of unmarried people. The resulting cross-classified data (observed
frequencies) of each educational assortative mating is given in Table 1A for Japanese
couples and in Table 1B for couples in the United States.
We use log-linear models which are fitted to the cross-classified data for Japanese
couples and couples in the United States. The greatest advantage of log-linear models
is that they can estimate the likelihood of couple formation of the specific educational
combinations with the specifications of interaction parameters which we explain in thefollowing, while controlling for different marginal distributions of education for men
and women.
We take female education as a row variable and male education as a column variable.
Partnership status is a layer variable, for which we classify couples into either married
5

Note that the sample is restricted to those of the ages of 20 to 44 at the time of thesurvey in order to assure comparability of the age range with the JLPS. We also restrict
our analysis to respondents who form couples of the same race (racially homogamous
couples). We obtained the dataset from the website of the National Survey of Family
Growth.
3

or unmarried status in the JLPS and either dating, cohabitating or married status in the
NSFG6. Thus our log-linear models are estimated for the three way table (row bycolumn by layer). The same analytical strategy is applied to both the JLPS and the
NSFG. We start from the model in which each diagonal cell in a different educationand in a different partnership state has a unique parameter, which is equivalent to the
Quasi-Independence model in the social mobility literature. With this model as abenchmark, we apply different log-linear models to the three way table and seek toarrive at the best-fitting model in our analysis to describe the pattern of association
between men’s and women’ education. Each of the models we apply differs in thespecifications of interaction parameters. The differences among the models can bedemonstrated usually in a design matrix form, which we display in Figure 1A for the
JLPS and in Figure 1B for the NSFG respectively.
After estimating these different log-linear models for the JLPS and the NSFG separately,
we step to the standard model selection procedure which is based on Likelihood Ratio
Chi-squared statistics (L-squared) and Bayesian Information Criteria (BIC). The
obtained statistics for each model are reported in Table 2A for the JLPS and in Table 2Bfor the NSFG respectively. The statistics clearly show our best-fitting model for Japanis Model 6 and the one for the United States is Model 7. Thus we report the results ofeach our best-fitting model for Japan and the United States in the next section.7
3. PATTERNS OF EDUCATIONAL ASSORTATIVE MATING
Figures 2 and 3 show the pattern of educational assortative mating in Japan among
unmarried couples (Figure 2) and married couples (Figure 3).8 The figures show
which combinations of education are found significant among the couples, and the bars
represent the presence of significant association. Among unmarried couples, educational
6

Previous research found a strong tendency of racial homogamy in the United Statesin addition to educational one. This suggests that our analysis should incorporate race asanother layer variable. We estimated models allowing for patterns of educational
assortative mating to vary by race, Whites and Non-whites. The model comparison tests,
however, indicated that the models were not significantly different by race. So we
present the results which assume the same model for Whites and Non-whites.
7
We first analyzed data separately for Japan and the United States. Once we arrived
at the best-fitting model for each nation, we conducted statistical tests for the differencein parameters across nations.
8
The figures plot the log multiplicative parameters estimated from our best fitting
model.
4homogamy is found at the top and bottom levels of education: men and women withcollege education are more likely to become partners with each other, and men andwomen with high school education are more likely to become partners with each otherthan people with other combinations of education. The degree of homogamy isstronger among college-educated couples than among couples with high school
education. Among married couples, the same pattern of educational homogamy isfound. In addition, there is a tendency of hypergamy (marrying up) among womenwith junior college education: women who graduated from junior college are more
likely to get married with men who graduated from four-year university.9 The mostimportant finding in Japan is that the patterns of educational assortative mating aredifferent among unmarried and married couples. There is a more apparent structuring
among married couples.
The strength of educational homogamy amongcollege-educated couples is stronger among married couples than among unmarried
couples. There is an additional association of hypergamy among married couples.
Figure 4 presents the pattern of educational assortative mating among couples in the
United States. Although we distinguished married couples, cohabitation couples, anddating couples, the pattern of association is the same among three types of couples.
The actual pattern of association in the United States resembles that in Japan. First,
there is a strong tendency for people with B.A. degrees to form partnerships, and thislevel of educational homogamy is almost the same as that among Japanese married
couples. Second, at the lowest level of education, there is a tendency of educational
homogamy: those with high school education tend to form partnership with each other.
The extent of homogamy is significantly stronger than that in Japan. The reason forthe strong level of homogamy derives from the fact that more than 40 percent of thosewith high school education are high school dropouts in the United States. High school
dropouts constitute the lowest level of educational attainment, and tend to have difficult
times in finding partners with higher levels of education. Those with high school
diploma tend to form partnership with those with a similar level of education but theextent of homogamy is lower than that among high school dropouts. Third, womenwith AA degrees have a tendency of hypergamy, that is, marrying up or forming
partnership with those with BA degrees. In addition, women with some college have atendency to find partners who have education lower than themselves. Because women
9

The second level of education includes women who attended technical colleges(senmon gakko) in addition to junior college. However, the tendency of hypergamy isobserved only among women with junior college diploma.
5with some college are composed of those with AA degrees and those who dropped outof the college, they have propensity to form partnership with those with different levelsof education.
4. DISCUSSION
Our paper is the first systematic attempt to distinguish the pattern of educational
assortative mating between married and unmarried couples in Japan. As far as we know,
none of the previous research examined the pattern of educational association undercourtship.

The most significant finding of our analysis is the difference in the patternof educational assortative mating between married and courtship couples in Japan.
Educational levels of the couples are more structured among married couples: there isapparently a stronger educational homogamy among married couples who graduatedfrom college and a propensity for women with junior college education to marry withmen of college education. In other words, dating unmarried couples seem to place lessemphasis on the educational level of the partner than married couples. It is, therefore,possible to speculate that education and other characteristics of the partner are taken
more seriously in deciding on a marriage partner than searching for a courtship partner.
Japanese people may be drawing a clear distinction in mate selection procedure between
courtship and marriage
In contrast, in the United States, the same pattern of educational association
characterized three types of couples: dating, cohabitation and married couples.
Regardless of the types of coupling, Americans tend to take serious account of theeducational level of the partner. There is a clear propensity to find partners with thesame level of education at the top and the bottom of educational hierarchy. In otherwords, the difference between marriage mating and pre-marriage mating (cohabitationand dating) is not obvious as far as partner’s educational association is concerned.
Unlike Japan, marriage partnership in the United States may not be a special
relationship which is clearly distinguished from courtship Other research in the UnitedStates showed the continuous transition from pre-marital to marital stage. For example,
Thornton, Axinn and Xie (2007, p.86) report that about three-fifths of young people“who had cohabited reported that they planned to marry their partner before they started
to live together.” Cohabitations tend to occur with clear plans for marriage. Our dataalso suggest a similar finding; 26 percent of our Japanese married couples had
experience of cohabitation with the marriage partner prior to marriage, while 54 percent
6

of our American married couples did so. There is a much smoother transition fromcohabitation to marriage in the United States. The difference in the pattern ofeducational assortative mating between pre-marital and marital couples in Japan may
reflect the element of discontinuous transition from courtship and marriage.

7

REFERENCES
Blackwell, Debra L. and Daniel T. Lichter, 2004, “Homogamy among Dating, Cohabitating, and Married Couples,” Sociological Quarterly Vol.45(4): 719-737.
Blossfeld, Hans-Peter, 2009, “Educational Assortative Marriage in Comparative PerSpective,” Annual Review of Sociology Vol.35: 513-530.
National Institute of Population and Social Security Research, 2007, Wagakuni Fufu no
Kekkon Katei to Shushoryoku: Dai-13-kai Shusho Douko Kihon Chosa (Marriage
Process and Fertility of the Married Couple in Japan: The 13th Japanese Fertility
Survey). Kousei Toukei Kyokai.
Schwartz, Christine R. and Robert D. Mare, 2005, “Trends in Educational Assortative
Marriage from 1940 to 2003,” Demography Vol.42(4): 621-646.
Miwa, Satoshi, 2005, "Educational Homogamy in Contemporary Japan," Social Science
Japan No. 33 (December) : 9-11.
Schwartz, Christine R., 2010, “Pathways to Educational Homogamy in Marital andCohabitating Unions,” Demography Vol.47(3): 735-753.
Shida, Kiyoshi, Kazuo Seiyama, and Hideki Watanabe, 2000, "Kekkon Shijo no Henyo"(Changes in the Marriage Market), pp.159-176, in Nihon no Kaiso Shisutemu 4:
Jenda, Shijo, Kazoku, (Social Stratification System in Japan 4: Gender, Market, andFamily). Tokyo. University of Tokyo Press.
Shirahase, Sawako, 1999, "Kaikyu-Kaiso, Kekkon to Jenda: Kekkon ni Itaru Patan"(Social Stratification, Marriage, and Gender: A Study of the Pattern of Association in
Marriage), Riron to Hoho (Sociological Theory and Methods) 14(1): 5-18.
Thornton, Arland, William, G. Axinn, and Yu Xie, 2007, Marriage and Cohabitation.
University of Chicago Press.

8Figure 1A. Specification of Interaction Parameters in Design Matrix Forms *1 *2-JapanModel = JP1

Unmarried Couples

Married Couples

Male

Male

FemaleHS or Less

Some College

BA or More

FemaleHS or Less

Some College

BA or More

HS or Less

1

0

0

HS or Less

4

0

0

Some College

0

2

0

Some College

0

5

0

BA or More

0

0

3

BA or More

0

0

6

Model = JP2

Unmarried Couples

Married Couples

Male

Male

FemaleHS or Less

Some College

BA or More

FemaleHS or Less

Some College

BA or More

HS or Less

1

0

0

HS or Less

1

0

0

Some College

0

2

0

Some College

0

2

0

BA or More

0

0

3

BA or More

0

0

3

Model = JP3

Unmarried Couples

Married Couples

Male

Male

FemaleHS or Less

Some College

BA or More

FemaleHS or Less

Some College

BA or More

HS or Less

1

0

0

HS or Less

3

0

0

Some College

0

0

0

Some College

0

0

0

BA or More

0

0

2

BA or More

0

0

4

9

(Figure 1A, continued)
Model = JP4

Unmarried Couples

Married Couples

Male

Male

FemaleHS or Less

Some College

BA or More

FemaleHS or Less

Some College

BA or More

HS or Less

1

0

0

HS or Less

1

0

0

Some College

0

0

0

Some College

0

0

0

BA or More

0

0

2

BA or More

0

0

2

Model = JP5

Unmarried Couples

Married Couples

Male

Male

FemaleHS or Less

Some College

BA or More

FemaleHS or Less

Some College

BA or More

HS or Less

1

0

0

HS or Less

1

0

0

Some College

0

0

0

Some College

0

0

0

BA or More

0

0

2

BA or More

0

0

3

Model = JP6

Unmarried Couples

Married Couples

Male*our best-fitting model

Male

FemaleHS or Less

Some College

BA or More

FemaleHS or Less

Some College

BA or More

HS or Less

1

0

0

HS or Less

1

0

0

Some College

0

0

0

Some College

0

0

4

BA or More

0

0

2

BA or More

0

0

3

*1 Each number in a cell represents a distinctive interaction parameter within a design matrix. Cells sharing the same number
are assigned the corresponding same interaction parameter within the matrix.
*2 Cells sharing zero are assigned no interaction parameters within the matrix.
10

Figure 1B. Specification of Interaction Parameters in Design Matrix Forms *1 *2-the United StatesDating Couples

Model = US1

Cohabitating Couples

Male
Some College College or More

FemaleHS or Less

HS or Less

10

Some College

0

College or More0

HS or Less

7

0

0

5

0

Some College

0

8

0

0

6

College or More

0

0

9

0

2

0

Some College

0

0

3

College or More0

Cohabitating Couples

Male
Some College College or More

1

0

0

College or More0

FemaleHS or Less

Male
Some College

College or More0

HS or Less

1

0

0

2

0

Some College

0

2

0

0

3

College or More

0

0

3

HS or Less

0

HS or Less

1

0

2

0

Some College

0

0

3

College or More0

Cohabitating Couples

Male
Some College College or More

FemaleHS or Less

1

0

0

HS or Less

Some College

0

0

0

College or More

0

0

2

HS or Less

10

Some College

0

College or More0

FemaleHS or Less

Male
Some College

College or More

0

3

0

HS or Less

50

Some College

0

0

0

Some College

0

0

0

College or More

0

0

4

College or More

0

0

6

Cohabitating Couples

Male
Some College College or More

HS or Less

Married Couples

Male
Some College College or More0

Dating Couples
FemaleMarried Couples

Male
Some College College or More

FemaleDating Couples

Model = US404

Some College

HS or Less

College or More

HS or Less

HS or Less

HS or Less

Male
Some College

0

HS or Less

FemaleHS or Less

HS or Less

FemaleModel = US3

FemaleFemaleDating Couples

Model = US2

Married Couples

Male
Some College College or More

FemaleHS or Less

Male
Some College

College or More0

HS or Less

1

0

0

0

0

Some College

0

0

0

0

2

College or More

0

0

2

FemaleHS or Less

0

HS or Less

1

0

0

0

Some College

0

0

2

College or More

0

11

Married Couples

Male
Some College College or More( Figure 1B, continued)
Dating Couples

Model = US5

Cohabitating Couples

Male
Some College College or More

FemaleHS or Less

HS or Less

10

Some College

0

College or More

0

0

0

0

0

Some College

0

0

0

0

1

College or More

0

0

1

0

0

Some College

0

0

1

College or More0

Cohabitating Couples

Male
Some College College or More

0

0

0

0

4
2

Married Couples

Male
Some College College or More

FemaleHS or Less

HS or Less

1
3

0

0

0

0

0

4
2

Some College
College or More

Dating Couples
HS or Less

HS or Less

1
3

0

0

0

0

0

3
2

FemaleHS or Less

HS or Less

Some College

College or More

Male
Some College

College or More

1
3

0

0

0

0

0

4
2

FemaleHS or Less

HS or Less
Some College
College or More

Cohabitating Couples

Male
Some College College or More

FemaleCollege or More

1

0

0

Some College

0

1

1
3

*our best-fitting modelCollege or More

HS or Less

0

HS or Less

Model = US7

Male
Some College

HS or Less

HS or Less

College or More

HS or Less

HS or Less

FemaleSome College

FemaleFemaleDating Couples

Model = US6

Married Couples

Male
Some College College or More

Married Couples

Male
Some College College or More

1
3

0

0

0

0

0

3
2

FemaleHS or Less

Some College

College or More

Male
Some College

College or More

1
3

0

0

0

0

0

3
2

HS or Less

*1 Each number in a cell represents a distinctive interaction parameter within a design matrix. Cells sharing the same number are
assignedthecorrespondingsame
parameter
withinthe matrix.
*2 Cells
sharing zero
areinteraction
assigned nointeraction
parameters
within the matrix.

12

Figure 2. Pattern of Educational Assortative Mating among Unmarried Couples
in JapanFigure 3. Pattern of Educational Assortative Mating among Married Couples in
Japan
13

Figure 4. Pattern of Educational Assortative Mating among Couples in the UnitedStates14

Table 1A. The Observed Frequencies for Educational Assortative Mating
across Different Partnership Status in Japan *1
Unmarried Couples *2
FemaleHS or Less
Some College
BA or More

HS or Less

74
52
31

Married Couples

Male
Some College BA or More

22
63
36

51
92
202

FemaleHS or Less
Some College
BA or More

HS or Less

Male
Some College BA or More

591
433
69

208
334
65

218
556
489

*1 The dataset for Japan is the Japanese Life Course Panel Survey.
*2 For Japanese sample, the partnership status is assumed to take either one of the two kinds of the status: the t"Unmarried" or "Married".

Table 1B. The Observed Frequencies for Educational Assortative Mating
across Different Partnership Status in the United States *1
WHITE
Dating Couples *3
FemaleHS or Less
Some College
BA or More

HS or Less

114.31
68.58
20.68

Male
Some College BA or More

55.16
103.4255.52*2Cohabitating Couples

16.33
48.63
111.04

FemaleHS or Less
Some College
BA or More

HS or Less

65.32
30.12
10.52

Married Couples

Male
Some College BA or More

18.87
34.47
22.86

5.44
15.97
41.73

FemaleHS or Less
Some College
BA or More

HS or Less

176.36112.86
50.44

Male
Some College BA or More

74.75
127.73112.4929.76
77.29
342.92

NON-WHITE
Dating Couples
FemaleHS or Less
Some College
BA or More

HS or Less

257.28 *4
79.47
18.87

Cohabitating Couples

Male
Some College BA or More

62.05
76.93
31.93

12.34
19.96
38.10

FemaleHS or Less
Some College
BA or More

HS or Less

186.1638.10
5.81

Married Couples

Male
Some College BA or More

25.76
22.14
5.81

3.63
3.63
5.81

FemaleHS or Less
Some College
BA or More

HS or Less

336.03
82.37
33.39

Male
Some College BA or More

60.96
55.16
36.29

12.70
31.93
99.79

*1 The dataset for the United States is the National Survey of Family Growth 2006-2010.
*2 The kinds of value are assigned for indicating the racial difference: "White" and "Non-White". Note that the model selection has
rejected the model assuming the racial difference in educational assortative mating patterns.
*3 For the United States' sample, the partnership category is assumed to take either one of the three kinds of the status: "Dating", "Cohabitating" or "Married".
*4 The cell frequency in the United States takes non-integral value because of weighting.

15

Table 2A. The Model Selection for Japanese Couples
MODEL

JP1
JP2
JP3
JP4
JP5
JP6 *our best fitting model

L-squared *2

D.F. *3

BIC *42.74

2-13.6314.30

5-26.6317.82

4-14.9223.06

6-26.0417.89

5-23.045.16

4-27.58*1 See Figure 1A for the specification of each model*2 L-squared stands for the Likelihood Ratio Chi-squared Statistics.
*3 D.F. stands for degree of freedom.
*4 BIC stands for Bayesian Information Criteria.

Table 2B. The Model Selection for Couples in the United States
MODEL

US1
US2
US3
US4
US5
US6
US7 *our best fitting model

L-squared *1

D.F. *2

BIC *36.83

15-115.949.03

21-162.8536.76

18-110.5738.40

22-141.6747.28

23-140.978.79

20-154.91

9.03

21-162.85*1 See Figure 1B for the specification of each model*2 L-squared stands for the Likelihood Ratio Chi-squared Statistics.
*3 D.F. stands for degree of freedom.
*4 BIC stands for Bayesian Information Criteria.

16東京大学社会科学研究所パネル調査プロジェクトについて
労働市場の構造変動、急激な少子高齢化、グローバル化の進展などにともない、日本社会における就業、結婚、家族、教育、意識、ライフスタイルのあり方は大きく変化を遂げようとしている。これからの日本社会がどのような方向に進むのかを考える上で、現在生じている変化がどのような原因によるものなのか、あるいはどこが変化してどこが変化していないのかを明確にすることはきわめて重要である。
本プロジェクトは、こうした問題をパネル調査の手法を用いることによって、実証的に解明することを研究課題とするものである。このため社会科学研究所では、若年パネル調
査、壮年パネル調査、高卒パネル調査の３つのパネル調査を実施している。

本プロジェクトの推進にあたり、以下の資金提供を受けた。記して感謝したい。

文部科学省・独立行政法人日本学術振興会科学研究費補助金
基盤研究 S：2006 年度～2009 年度、2010 年度～2014 年度
厚生労働科学研究費補助金
政策科学推進研究：2004 年度～2006 年度
奨学寄付金
株式会社アウトソーシング（代表取締役社長・土井春彦、本社・静岡市）：2006 年度～2008 年度

東京大学社会科学研究所パネル調査プロジェクト
ディスカッションペーパーシリーズについて
東京大学社会科学研究所パネル調査プロジェクトディスカッションペーパーシリーズは、
東京大学社会科学研究所におけるパネル調査プロジェクト関連の研究成果を、速報性を重視し暫定的にまとめたものである。

東京大学社会科学研究所 パネル調査プロジェクト
http://ssjda.iss.u-tokyo.ac.jp/panel/