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 among Unmarried andMarried Couples
in Japan and the United States
Hiroshi Ishida（Institute of Social Sciences, University of Tokyo）

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

February 2014
No.72

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. 72
February, 2014

Educational Assortative Mating among Unmarried and Married Couples
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 Japanese panel data is obtained from the Research Planning
Committee of the Japanese Life Course Panel Surveys. This research was supported by
Grant-in-Aid for Scientific Research (S) (numbers 18103003 and 22223005) from the Japan
Society for the Promotion of Science (JSPS). The research support in conducting the panel
surveys from the Institute of Social Sciences, University of Tokyo, and the Outsourcing
Company is gratefully acknowledged. The authors are grateful to Shin Arita, Satoshi Miwa,
Katsunori Ogawa, Hirofumi Taki, and Koji Yamamoto for helpful comments.

Educational Assortative Mating among Unmarried and Married Couples
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
This study 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 investigated the pattern of educational association among
unmarried couples. The most significant finding of our analysis is the difference in thepattern of educational assortative mating between married and courtship couples in Japan.
Educational homogamy at the top and the bottom of the educational hierarchy
characterizes the educational association among both unmarried and married partners.
However, among married couples, there is apparently a stronger educational homogamy
for couples who graduated from four-year universities and a propensity for women withjunior college educations to marry men with B.A. degrees. Japanese unmarried couples
seem to place less emphasis on the educational level of their partners than married
couples. We speculate that Japanese youth hold different standards of mate selection forcourtship than for marriage. To highlight the distinctive patterns of Japanese couples, we
present the results of comparative analyses of the United States. Regardless of the typeof partnership, Americans appear to take serious account of their partners’ educational
level. There is a much smoother transition from cohabitation to marriage in the UnitedStates. The difference in the pattern of educational assortative mating between
pre-marital and marital couples in Japan may reflect a discontinuous transition fromcourtship to marriage.

Keywords: educational assortative mating, cross-national comparison, marriage, courtship1. INTRODUCTION
The study of social stratification investigates similarity of class positions (class inheritance)
across and within generations in order to determine the degree to which a society is closed
or open.

Similarities between partners in matched couples function to maintain theboundaries between social groups, and the barriers to inter-marriage constitute one of themost important factors contributing to closure in societies. Couples frequently marry on
the basis of various matched characteristics, producing a pattern of marriage homogamy
and assortative mating. A variety of demographic and socio-economic factors, including
race, religion, sexual orientation, class background, education, and occupation, are taken
into account when couples form a union. Among these factors, education is one of themost well established indicators to have emerged from studies of assortative mating(Blossfeld 2009; Kalmijin 1998; Schwartz 2013). Education imparts skills which determine
socio-economic success as well as cultural resources that influence lifestyles and partner
preferences.

The conventional approach to the study of educational assortative mating examinedmarried couples. The main research question concerned educational assortative mating
among married couples: who marries whom?

Among Japanese scholars who havestudied social inequality, Shirahase (1999) and Shida et al. (2000) represent earlysystematic attempts to analyze educational association among married couples. Thesestudies report a strong tendency toward educational homogamy among married couples
with both partners having either a low or a high level of education. Miwa (2005) examines
the trends in educational homogamy in post-war Japan and concludes that educational
homogamy was stable until the 1970s but shows a declining trend since then.

The past decades have seen the tremendous increase of cohabitation among unmarried
couples in the United States and European countries (Heuveline and Timberlake 2004;
Kiernan 2001; Seltzer 2000; Smock 2000; Thornton, Axinn and Xie 2007), awell-documented fact which motivated researchers to examine the difference in the patternof assortative mating between married couples and unmarried couples (Blackwell and
Lichter 2000, 2004; Hamplova 2009; Qian 1998; Schoen and Weinick 1993; Schwartz2010). Recent progress in data gathering on unmarried couples led to this new
development, particularly in the United States.

Researchers can now reframe theresearch question as follows: who mates with whom among dating, cohabitating, andmarried couples?

Japanese society has not experienced the dramatic increase of cohabitation as observedin the United States or Europe. According to the 14th Japanese National Fertility Survey
conducted in 2010, only two percent of unmarried male and female respondents aged 18 to
50 reported that they were cohabitating with a partner at the time of the survey, and anotherfive to six percent of respondents had cohabitated in the past (National Institute ofPopulation and Social Security Research 2012b).

These figures underestimate theprevalence of cohabitation, because the survey excluded married respondents. The first
National Survey on Population, Family, and Generations in Japan, conducted in 2004,
included both married and unmarried female respondents aged 20 to 49, and put the
proportion of cohabitation at about 20 percent (Iwasawa 2005). The International Surveyof Attitudes on Low Fertility Society conducted in 2005 reported that 14 percent ofrespondents aged 20 to 49 including both married and unmarried people had experience
with cohabitation (Cabinet Office of Japan 2006), and the same survey conducted again in2010 reported the figure to be 22 percent (Cabinet Office of Japan 2011). While thesestatistics may point to a rising trend of cohabitation in Japan, although at a much smallerscale than in the West, Raymo et al. (2009, p. 785) claim that cohabitation in Japan is “bestviewed as an emerging prelude to marriage rather than as an alternative to marriage orsinglehood.”

Unmarried couples and courtship as a partnership status, however, are no longer
uncommon in contemporary Japan. Contrary to the situation several decades ago, when
the predominant form of marriage occurred through introductions arranged by relatives andsuperiors (“arranged marriages”), today most marriages are “love marriages” (ren-ai
kekkon) based on spontaneous romantic encounters. The majority of marriages were“arranged marriages” until the mid-1960s, but “love marriages” have since become much
more common, as shown in Figure 1; these data come from the calculations by the
National Institute of Population and Social Security Research (2012a). Today 87 percent
of married couples report their marriages as “love-marriages” while only six percent reportthat they are in “arranged marriages.” This change implies that many married couples
must have experienced romantic relationships and the courtship state prior to marriage.
Although cohabitation is not widespread, courtship has become an important life stage forJapanese youth. We therefore examine the topic of assortative mating by expanding ourscope to include unmarried couples into the analysis of Japanese data. To our knowledge,
there is no previous research which distinguishes the patterns of educational assortative
mating between married and unmarried couples in Japan. The first contribution of thisstudy is, therefore, to present the systematic account on educational assortative mating
among both unmarried and married couples in Japan.

Comparison between Japanese married and unmarried couples will contribute to ourunderstanding of marriage behavior in Japan. Courtship behavior of unmarried couples
including the pattern of assortative mating is one of the most under-explored topics inJapanese sociological studies in general and marriage studies in particular, despite thepotential importance of its role as the transitory state leading to marriage. Our explicit
distinction of couples by partnership status will highlight the dynamic process fromcourtship to marriage.

2. CROSS-NATIONAL COMPARISON WITH THE UNITED STATESThe second contribution of this study comes from the cross-national comparison. This
study focuses on the examination of Japanese society, but also offers some comparative
evidence from the analysis of U.S. society. Cross-national studies comparing Japan andother nations have been conducted on the topics of social mobility (Erikson and Goldthorpe
1992; Ishida 1993) and educational attainment (Blossfeld and Shavit 1993; Shavit andMuller 1998; Shavit, Arum, and Gamoran 2007).

However, studies dealing witheducational assortative mating are limited.

Smits and his colleagues’ studies on comparative educational homogamy (Smits 2003;
Smits and Park 2009; Smits et al. 1998, 2000) include Japan as one of many countries.
Designated as the “Confucian” block, East Asian nations including Japan generally show ahigher extent of educational homogamy compared with other nations (see also Raymo andXie 2000). Smits and Park (2009) show that Japan is located in the middle of the group of
ten East Asian nations in terms of its degree of educational homogamy.

The mainobjective of these studies is to explain the differences among societies and their trends
using macro sociological variables, such as modernization and expansion of education, butthese studies have rarely paid attention to the institutional features of individual nations.

Furthermore, most of these studies concentrate on educational homogamy, the association
with partners who have the same level of education. We will examine the detailed patternof association of educational level of partners, including homogamy, hypergamy(association with people with higher educational level), and hypogamy (association withpeople with lower educational level).

In this paper, we present comparative analyses of sociological data from the United States
and Japan in order to highlight the distinct patterns of educational assortative mating inJapan. The two societies are both advanced industrial nations, but they are different inmany respects. In addition to the differences in patterns of cohabitation and courtshipdescribed above, the two societies differ in their educational upgrading and genderdifferences in educational attainment.

The higher education system has been more

extensively developed in the United States than in Japan. More importantly, the gender
gap in participation in higher education is completely reversed, and women are more likely
to obtain undergraduate degrees than men in contemporary American society (DiPrete andBuchmann 2013). In Japan, women still lag far behind men in educational attainment.
The attendance rate at four-year universities is over fifty percent (54%) among men, andonly about 40 percent among women. The gender gap has been gradually closing sincethe 1990s, primarily because more women are choosing to attend four-year universities
rather than two-year junior colleges (Ishida 2007; Matsui 1997).

These differences imply that the educational distributions of partners (that is, the marginal
distributions of the cross-classified table showing male and female partners’ education)
should look more equal in the United States. In Japan, the difference in the educational
distribution of male and female partners should be more apparent. Due to the more equal
participation of both genders in higher education in the United States, we expect that the
proportion of couples that have the same level of education (educational homogamy)
should be higher in the United States. However, this finding does not necessarily meanthat the association is stronger in the United States. For example, even if the tendency forcollege graduates to choose partners with the same level of education is the same
between the two societies, American college graduates will still a show higher proportion of
educationally homogamous couples because there are more college graduates in the
United States. We will employ log-linear and log-multiplicative models to estimate thepattern and strength of association between partners’ education levels after controlling forthe difference in educational attainment between male and female partners. Our analyses
will allow us to compare the two societies based on the pattern and the strength ofassociation in partners’ educational matching.

3. LIFE COURSE TRANSITION FRAMEWORKThe third contribution of this study comes from the life course transition framework, which
is used to study educational assortative mating. Previous research often juxtaposed thepattern of educational association between unmarried and married couples. However,there is a dynamic life course transition from courtship to marriage. We aim to take thisdynamic process into account.

Figure 2 shows our analytical framework for the analysis of the process of transition fromcourtship relationships to marriage. We begin with the figure for Japan (top part). In
Japan, in addition to the distinction between married couples and unmarried couples, weare able to disaggregate unmarried couples into different premarital relationships. First,
by taking advantage of the panel nature of the data set, we can differentiate between
couples whose relationship continued and those whose relationship ended during theobservation period. If we assume a sequence of courtship to marriage, those couples
whose romantic relationships ended will not experience a transition to marriage. The
comparison of these two types of couples gives us information about the transition fromcourtship to dissolution: which kinds of couples are likely to end their relationships. The
solid line from courtship to dissolution indicates that we are able to evaluate this transition
using our data.

In order to examine the transition process from continuing courtship to marriage, we
introduce the notion of “marriage intention.” We assume that couples who continued theirrelationships and have a strong intention of getting married are more likely to experience atransition to marriage, thereby showing a more similar pattern of educational assortative
mating to married couples than couples who continued their relationships and have arelatively weak intention of getting married. We use the notion of marriage intention as anindicator of the pathway from courtship to marriage. The solid lines from courtship to“strong marriage intention” and to “weak marriage intention” indicate that we will examine
the difference in the association pattern between the two groups. Because we had alimited observation window (six years) to detect the occurrence of marriage among those
who formed courtships during the earlier waves of our Japanese data set, we do not have asufficient sample of unmarried couples who got married. The dotted lines in Figure 2
indicate that our analysis is unable to address the question of transition to marriage due tothis data limitation.

As shown in the bottom part of Figure 2, in the United States, we will first make thefollowing distinctions among unmarried relationships: dating couples and cohabitation
couples. The successful transition of intimate relationships implies the pathway from asexually intimate dating relationship to cohabitation to marriage, so we will compare theeducational associations among all three groups: dating, cohabitating, and married couples.
With regards to the pathway from cohabitation to marriage, the notion of “marriage
intention” will be introduced. The pattern of educational assortative mating in cohabitating
couples with strong marriage intention will be compared with those with weak intention.

Finally, we focus on the pathway out of marriage. We distinguish married couples into
those who continued to live with the spouse and those who had separated from the spouseand compare the pattern of educational association between these two types of married
unions.

The strategy to focus on the dynamic process of transition follows the exemplary study by
Schwartz (2010) who proposed a stock-and-flow framework for the study of educational
homogamy of partners (see also Schwartz and Mare 2005, 2012).

Schwartz (2010)

examines the dynamic process of flows into and out of cohabitation and marriage, andargues that the stock of cohabitating and married couples in the population at any given
time is the result of selective entries and exits from cohabitation and marriage. We areable to compare the pattern of educational assortative mating between unmarried couples
who continued their relationships and those who exited from courtship based on Japanesedata.1 The U.S. data set does not allow us to study the exit from dating or cohabitation.

1

Unlike Schwartz (2010), our analyses do not compare new entrants (such as
newly-formed courtship couples and newly-wed married couples) with couples with long
duration. The Japanese data set used in our analyses enable us to distinguish both
unmarried and married couples by the duration of courtship or marriage, so analyses
similar to Schwartz can be conducted. However, the number of cases reduced
significantly.

However, we will conduct a supplementary analysis on comparisons of the educational
association between married couples who lived together and those who were separated in
the United States. The analysis provides indirect evidence of exit from marriage.

A key idea in understanding the dynamic process of transition from courtship to marriage is
the winnowing hypothesis (Blackwell and Lichter 2000, 2004). The winnowing hypothesis
claims that, as the intimate relationships progress, “transitions from dating to cohabiting tomarital unions are marked by increasing selectivity in the mate selection or matchingprocess” (Blackwell and Lichter 2004, p.719).

In the process of partner selection,

courtship couples tend to use less stringent criteria than married couples because
courtship requires less emotional and financial commitment than marriage. Education isused as a crucial criterion as it represents future socio-economic potential as well asshared values and lifestyles.

With regard to educational assortative mating, the winnowing hypothesis argues that theassociation between two partners’ education becomes stronger as more commitment
becomes necessary from courtship to marriage. We posit that the association is not
limited to the resemblance of education (homogamy) but includes other types ofassociation such as hypergamy (marrying up) and hypogamy (marrying down). If thepattern of educational association is the same (such as homogamy at the top and bottom
levels of education), the hypothesis predicts that the strength of association is stronger
among married than unmarried couples. The winnowing hypothesis also predicts that
there may be more structuring of association among married couples; both homogamy andwomen’s hypergamy may characterize marriage partnership while courtship partners may
simply show homogamy without the tendency of hypergamy. In other words, it can beassumed that the winnowing process involves not only the increased resemblance ineducation of couples but also the increased structuring of educational matching ofpartners.

Among unmarried couples, this hypothesis predicts that couples who continued theirrelationships show stronger association than couples who ended their relationships.
Finally, the hypothesis predicts unmarried couples with strong marriage intention to show
stronger association of partners’ education than those with weak marriage intention. Insummary, as the degree of commitment among couples becomes more demanding, thecriterion of matching becomes more stringent, and the educational association among thepartners becomes more structured.

4. DATA AND METHODS(1) Data
To characterize the distinct patterns of educational assortative mating, we use datasets
which allow us to specify different partnership types and educational levels for both married
and unmarried couples. We use the Japanese Life Course Panel Survey (JLPS) for the
analysis of Japanese couples.

The JLPS is a nationally representative panel survey

conducted annually by the Center for Social Research and Data Archives at the Universityof Tokyo. The sample design included men and women between the ages of 20 to 34(youth sample) and 35 to 40 (middle-aged sample) living in Japan during the first wave of
the survey conducted in 2007 2 .

For our analyses, we combined the youth andmiddle-aged samples. We use the information collected in wave 1 (2007) through wave 6(2012) when the respondents were between the ages of 25 to 45.

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 thesurvey period. We use the 2006-2010 survey, which was conducted from June 2006 toJune 20103.

(2) Variables
Education Level
We employ three categories of education level for both Japanese and American couples:(1) “high school or less,” (2) “junior college” (JLPS) or “some college” (NSFG), and (3) “B.A.
or more.” Category 2 needs further clarification; “junior college” in the JLPS includes
2

For more detailed information about the JLPS, please refer to the website
http://ssjda.iss.u-tokyo.ac.jp/en/panel/purpose/.
3
We restricted our analyses to include only respondents aged 20 to 45 at the time of thesurvey in order to assure comparability of the age range with the JLPS. We obtained thedata set from the website of the NSFG ( http://www.cdc.gov/nchs/nsfg.htm ).

those who attended technical colleges (senmon gakko) or two-year junior colleges. For
the NSFG, “some college” includes those who attended a two-year college but not afour-year college as well as those who dropped out of college.

Partnership Types
To investigate the differing pattern and strength of educational assortative mating in theprocess of couples’ transition from unmarried to married, our approach specifies relevant
partnership types for each nation.

Japanese Partnership Types:

For Japanese couples, we specify three distinctions

between partnership types.

The first distinction is between unmarried couples andmarried ones. The analysis of this comparison is denoted as “JP Analysis 1” in theanalyses section. Unmarried couples are defined as both partners being unmarried at thetime of the survey of the JLPS. Married couples consist of two married partners at thetime of the JLPS survey. We cross-classify the male partner’s education by the female
partners’ education, and present a two-way table for unmarried and married couples inTable 1A.

Second, we consider the possibility of distinguishing among unmarried couples.

The

analysis is denoted as “JP Analysis 2.” We distinguish between unmarried couples who
continued their relationship and those whose relationship dissolved over the study period.
The longitudinal aspect of the JLPS enables us to identify whether an unmarried
respondent had an unmarried partner at the time of the survey and how long therelationship persisted.

We use these pieces of information to determine whether

unmarried couples maintained their relationships or dissolved them. Let us consider an
example in which an unmarried respondent had an unmarried partner during the 2010
survey. If the respondent stayed unmarried and had no partner during the 2011 survey,
her or his relationship was judged to be dissolved. It was also judged to be dissolved if
the respondent had an unmarried partner but the relationship persisted for less than one
year. Having a partner over two consecutive years does not necessarily mean that it was
the same partner. If the relationship lasted for less than one year, the partners in the twoconsecutive years are judged to be different. Moreover, if the unmarried respondent did
not participate in the 2011 survey (attrition), the relationship was judged to have continued
in our analysis.

Cross-classification of educational level of partners for couples who

continued their relationships and for couples who ended their relationships are shown in
Table 1B.

The third distinction is concerned with the intention of getting married among unmarried
couples who continued their relationships during the observation period. We call this setof analysis “JP Analysis 3.” The JLPS asks an unmarried respondent how strong her or
his marriage intention is on an ascending scale of 1 to 5. Using this information, weclassify those who chose the top two scale points as having a “strong intention” and those
who chose the other three as having a “weak intention.” We show the cross-classificationof partners’ education for these two types of couples in Table 1C.

U.S. Partnership Types: We specify four kinds of categories of partnership types in our
analysis of couples in the United States. We use each of the differences as a layer
variable in our analysis of educational assortative mating.

First, we examine the difference between unmarried couples and married couples(US-Analysis 1). Note that the NSFG distinguishes two categories of unmarried couples;
unmarried couples who are in a sexually intimate relationship but not living together, andcohabitating couples. We call the first one “dating” and the second “cohabitating.” Thus,
the “unmarried couple” category in our analysis is an aggregated category which consistsof both “dating” and “cohabitating” couples. Cross-classifications of the male partner’s
education by the female partners’ education for unmarried and married couples are shownin Table 2A.

The second distinction involves the disaggregation of unmarried couples into either “dating”
or “cohabitating.” We call this set of analysis “US-Analysis 2.” US-Analysis 2 consists of
two parts. The first part is the examination of the difference between dating couples andcohabitating couples, and the second part examines the difference between cohabitating
couples and married couples. Cross-classifications of educational level of partners fordating couples and cohabitating couples are shown in Table 2B.

The third difference is concerned with the disaggregation of cohabitating couples into two
types of partnership by marriage intention (US-Analysis 3). The first one consists of thosewith a strong intention to marry and the latter consists of couples with a relatively weak

intention to marry.

The NSFG asks unmarried respondents who have cohabitating

partners about their marriage intention on an ascending scale of 1 to 5. As for the JLPS
data, we classify those who chose the top two points as having a “strong intention” andthose who chose the lower three as having a “weak intention.”

We show thecross-classification of partners’ education for these two types of couples in Table 2C.

Fourth, we examine the difference among married couples: those who stayed together andthose who got separated (US-Analysis 4). We show the cross-classification of spouses’
education for these two types of married couples in Table 2D.

(3) Log-linear and Log-multiplicative Models
Given the cross-classified tables, we apply log-linear and log-multiplicative models to thedata for Japanese couples and for couples in the United States separately. The greatest
advantage of these models is that we can estimate the likelihood of couple formation basedon specific educational combinations by setting interaction parameters, while controlling fordifferent marginal distributions of education for men and women.

We assign female education as a row variable and male education as a column variable,
and we use partnership type as a layer variable4. For each partnership type, we ran
separate analyses: JP-Analysis 1 to 3 for Japanese couples and US-Analysis 1 to 4 forcouples in the United States. Thus, our models are estimated for the three-way table (rowby column by layer).

The same analytical strategy is applied to both the JLPS and the NSFG data. In eachspecific analysis, we start from a benchmark model. We then apply different log-linear
models to the three-way table and search for the model that best fits the data, which isused to describe the pattern of association between men’s and women’s education. Eachof the models we apply differs in the specifications of interaction parameters. We also
estimate log-multiplicative models, which allow the strength of association to be uniformly
4Previous research found a salient tendency of racial homogamy in the United States.
This might suggest that our analysis should control for race as another layer variable.
This approach may complicate the analysis, but can be useful when we attempt to analyze
detailed features of educational assortative mating. However, since our focus is on the
differences of educational assortative mating in the process of couples’ transition from anunmarried state to a married state, rather than a detailed feature of the mating, we do notconsider race in our analysis.

different between different types of partnerships while holding the pattern of association
constant across different types5. The differences among the models can be demonstrated
conveniently in a design matrix form, which we display in Table 3 for the JLPS and in Table
4 for the NSFG. Note that φ in matrix JP8 in Table 3 and matrix US8 in Table 4 indicates a
uniform-difference parameter in log-multiplicative model.

5. RESULTS(1) Descriptive Results for Japanese Couples
The analysis begins with a review of descriptive statistics of couples in Japan based on
their partnership type (Table 5).

Unmarried couples tend to be more educated thanmarried couples, both for male and female partners. On the other hand, married couples
tend to be more educationally homogamous (0.534) than unmarried couples (0.481). This
result is consistent with the prediction of the winnowing hypothesis. However, we need tobe cautious in interpreting this result because the proportion of educationallyhomogeneous couples is affected by the distribution of education of partners. Consider
the following example: If those with low education are more educationally homogamousthan others, the greater proportion of those with low education among married couples will
increase the overall proportion of educational homogamy. In order to control for the impactof the marginal distributions, we need to resort to log-linear and log-multiplicative models.
Shifting to the difference within unmarried couples, couples who continued theirrelationships tend to be slightly more educated than couples who dissolved theirrelationships, both for male and female partners.

The former also shows a higher

proportion of educationally homogamous couples (0.555) than in the latter (0.497).

(2) Patterns of Educational Assortative Mating in JapanThe following section contains the analyses of using log-linear and log-multiplicativemodels. Table 6 presents the results of fitting various models to the Japanese data set.

Japanese Analysis 1: Unmarried (A) and Married Couples (B)6

5

See Xie (1992) for a detailed explanation of the class of log-multiplicative models used in
our analysis.
6 A and B correspond to the types of partnership (Category A and Category B) in Table 3.

We begin our analysis with an examination of the difference in educational assortative
mating between married and unmarried couples using observed frequencies reported inTable 1A. Before we examine the transition process to marriage by disaggregating theunmarried couples, we first contrast married couples with unmarried couples overall. We
ran six hierarchically related log-linear models (Table 6, Analysis 1). The first model(Model 1-1) allows the strength of educational homogamy to be different both among thethree educational categories (high school or lower, junior college, and B.A. or higher) andpartnership type (unmarried or married). The design matrix (JP1) is shown in Table 3.
This model fits the data (p = 0.218) but leaves only two degrees of freedom. The second
model (Mode 1-2) constrains the three homogamy parameters to be the same between
unmarried and married couples (matrix JP2). The comparison of fit statistics between thefirst two models suggests that some of the homogamy parameters are identical between
unmarried and married couples.

It turns out that not only are the homogamy parameters for the junior college category
nearly identical across the two couple types, but they are also non-significant. Therefore,
the following models ignore the tendency of educational homogamy among those with a
mid-level education. Model 1-3 (matrix JP3) deletes the homogamy parameter for thejunior college category and sets the homogamy parameters for high school or lower and
B.A. or higher categories to be different across the two types. Model 1-4 (matrix JP4) alsodeletes the homogamy parameter for junior college but sets the other two homogamyparameters to be the same for unmarried and married couples. Model 1-5 (matrix JP5)
modifies the previous model and allows the homogamy parameter for university graduates
to be different between unmarried and married couples. According to the comparison of
fit statistics among these three models, Model 1-5 is the model that best fits the data.
Finally, Model 1-6 (matrix JP6) adds the tendency for marriage hypergamy for women who
completed junior college. These women show a propensity to marry men who reachedundergraduate education or higher.

The same propensity was not found among

unmarried couples. This model provides an excellent fit to the data (p = 0.702) and stillretains four degrees of freedom. The parameter estimates from Model 1-6, which is ourbest fitting model, are shown in Figure 3.

We use the same notation for the following Japanese analyses.

Figure 3 shows the matching combinations of education among the couples, and the bars
represent the presence of significant associations. Among unmarried couples (Figure 3A),
the tendency for educational homogamy is found at the top (B.A. or higher) and the bottom(high school or lower) levels of education, and the degree of homogamy is apparently
stronger at the higher level of education. Among married couples, the same pattern ofeducational homogamy at the upper and lower levels of education is observed.

In

addition, there is a tendency for hypergamy (marrying up) among women with juniorcollege education.7

A comparison of Figures 3A and 3B highlights the difference in educational assortative
mating between unmarried and married couples.

We observe that the strength ofassociation between partners’ education is much stronger among married couples thanunmarried couples, because the bar indicating homogamy among university graduates issignificantly higher among married couples and there is an additional tendency for women
who completed junior college to marry with men with a university education. In summary,
there is more structuring along educational lines among married couples than unmarried
couples.

Japanese Analysis 2: Unmarried Couples who Continued Relationship (A) and who
Dissolved Relationship (B)The second set of analysis focuses on unmarried couples and distinguishes between those
whose relationships continued and those whose relationships ended. Since the Japanesedata set is composed of panel-type data, we can determine whether the unmarried couples
continued or ended their relationship during the observation period.

We used theobserved frequencies reported in Table 1B.

The baseline model for this set of analysis is Model 2-1, and the matrix form of this model isshown in JP4 in Table 3. We already know from the previous analysis that there is atendency for educational homogamy at the upper and lower levels of education among
unmarried couples. Model 2-1 imposes identical degrees of homogamy at the upper andlower levels across the two partnership types: relationship continued and relationship7

The second level of education includes women who attended technical colleges (senmon
gakko) in addition to junior college. However, the tendency of hypergamy is observed
only among women with junior college diplomas.

dissolved. This model fits the data well (L-square = 7.449, df = 6, p = 0.281). When weallow the degree of homogamy among university graduates to differ between the two typesof partnership (matrix JP5), the model (Model 2-2) improves the fit (L-square = 4.387, df = 5,
p = 0.495). The improvement in L-square is 3.062 with one degree of freedom, and it issignificant at the ten percent level, but not at the five percent level. On the other hand,when we allow the degree of homogamy at the lower level of education (high school orless) to be different between the two types of partnership (matrix JP7), the model (Model2-3) shows little improvement in fit (L-square = 6.484, df = 5, p = 0.262).

Finally, we tested the model (matrix JP8) which allows the strength of association to beuniformly different between the two types of partnership (Model 2-4) while holding thepattern to be the same across partnership types. This model has an adequate fit to thedata (L-square = 4.330, df = 5, p = 0.503). The uniform-difference (uni-diff) parametersare 1.000 for unmarried couples whose relationship continued and 0.6298 for unmarried
couples whose relationship dissolved. These parameters imply that the association is
weaker among unmarried couples with dissolved relationships. There is a significant
improvement in fit by allowing the degree of homogamy at the upper level of education todiffer across partnership status, while there is a minimal improvement in fit by adjusting thelower level of education across partnership status.

From this, we conclude that thedegree of homogamy is not uniformly different at the upper and lower levels of education
and we are inclined to select Model 2-2 as the best fitting model for this set of analysis.

Figure 4 shows the parameter estimates from this model. Both types of partnership show
a similar pattern of association: men and women with high school or lower education are
more likely to partner with each other and men and women with four-year university
education are more likely to partner with each other than are people with different
combinations of education. However, the strength of homogamy among those with auniversity education is much stronger among couples whose relationship continued(1.5458) than those whose relationship ended (0.7758).

These results suggest that

unmarried couples are more likely to continue their partnership when the degree of
educational homogamy is strong. In particular, couples who are both highly educatedhave a clear propensity to maintain the relationship.

Japanese Analysis 3: Unmarried Couples with Strong (A) and Weak Marriage Intention (B)The third set of analysis conducted using the Japanese data set involves thedisaggregation of unmarried couples whose relationship continued.

We distinguishongoing courtship couples into two groups: couples with a strong intention to get married
and those with a relatively weak intention to get married.

The baseline model for this set of analysis is Model 3-1, and the matrix form of this model isshown in JP4 in Table 3. It is the same baseline model used in the previous analysis, andthe model imposes the same degree of educational homogamy at the upper and lower
education levels across the two groups differentiated by marriage intention. The model
fits the data well (L-square = 7.777, df = 6, p = 0.2549). When we allow the degree of
educational homogamy either at the top or the bottom to differ between couples with strong
intention and those with weak intention (Model 3-2 and Model 3-3 respectively), neither
model improves the fit over the baseline model.

Finally, when we fit a log-multiplicative model (Model 3-4) which imposes the same patternof educational homogamy but allows the strength of association to be uniformly different
between the two groups, the model fits the data (L-square = 7.252, df = 5, p = 0.203).
However, the fit does not improve significantly over the baseline model. Although theuniform-difference parameters are not significant, they are nonetheless informative:
couples with strong intentions to marry (1.000) show a stronger association than those withweak intentions (0.7678).

Indeed, if we compare the strength of association among

married couples, couples with a strong marriage intention, and couples with a weakmarriage intention using the log-multiplicative model (analysis not shown), the order ofassociation is as follows: married couples show the strongest association, unmarried
couples with a weak marriage intention show the weakest association, while unmarried
couples with a strong marriage intention are in the middle. These results suggest that theresemblance of couple’s education tends to increase as the couples go through thepathway from courtship to marriage.

(3) Descriptive Results for Couples in the United States
We first review descriptive results of couples by their partnership type in the United States(Table 7). Married couples tend to be more educated than unmarried couples both formale partners and female partners. Table 7 also shows that married couples tend to be
more educationally homogamous (0.610) than unmarried couple (0.601) but by a verysmall margin.

Table 7 presents descriptive statistics for two disaggregated types ofunmarried couples: dating couples and cohabitating couples. Dating couples tend to be
more educated than cohabitating couples, both for male partners and female partners.
However, cohabitating couples are more educationally homogamous (0.644) than dating
couples (0.582). Educational levels of the couples and the resemblance of education
among couples are not uniformly related across different types of partnerships. The effectof the marginal distributions needs to be controlled to estimate the propensity ofhomogamy among different partnerships.

(4) Patterns of Educational Assortative Mating in the United States
We next present the results of applying log-linear and log-multiplicative models to the U.S.
data in Table 8.

US Analysis 1: Unmarried (A) and Married Couples (B)8
We first examine the difference in educational assortative mating between unmarried
couples and married couples. We use observed frequencies reported in Table 2A. Nine
log-linear models are estimated (Table 8, US-Analysis 1). Each of the nine models ispresented in the design matrix form shown in Table 4. The first model (Model 1-1) allows
the strength of educational homogamy to vary both among the three educational
categories (high school or lower, some college, and B.A. or higher) and partnership type(unmarried or married). The second model (Model 1-2) constraints the three homogamyparameters to be the same between the two partnership types (matrix US2).

The

comparison of fit statistics between Model 1-1 and 1-2 indicates that some of the threehomogamy parameters are identical between unmarried and married couples, as was thecase for Japanese couples.

The results show that the homogamy parameters for the middle level (“some college”)
category are identical across the two types, and the coefficient is negative and significant.
The negative coefficient implies that people with some college education tend to marryheterogamously, that is, they marry partners with either a higher level or lower level of
education. This suggests that the pattern of educational heterogamy should be examinedamong those with some college education in the following models. Before focusing on
8

A and B correspond to the types of partnership (Category A and Category B) in Table 4.
We use the same notation for the following US analyses.

heterogamy, we first need to confirm whether the homogamy parameters for high school orlower and B.A. or higher categories are different across the two types. Model 1-3 (matrix
US3) allows the homogamy parameters for high school or lower and B.A. or higher
categories to vary across the two types while tentatively ignoring the “some college”
category. Model 1-4 (matrix US4) constrains the homogamy parameters for high schoolor lower and B.A. or higher to be identical between unmarried and married couples with noparameter set for some college. Model 1-5 (matrix US-5) sets the single homogamyparameter for high school or lower and B.A. or higher across unmarried and married
couples. The comparison of fit statistics among these models confirms that Model 1-4
best fits the data. We next examine educational heterogamy among those with somecollege education. Model 1-6 (matrix US6) and Model 1-7 (matrix US7) examine thepossibilities of marriage hypergamy and hypogamy for women with some college education.
The former sets different parameters for marrying up and marrying down, and the latter
constrains the parameters to be identical for marriage hypergamy and hypogamy. The
model comparison shows that Model 1-7 fits better than Model 1-6. Therefore, we choose
Model 1-7 as the best-fitting model in US-Analysis 19. The estimated parameters from
Model 1-7 are shown in Figure 5.

The bars in Figure 5 indicate the presence of a significant association. It should be notedthat Figure 5 represents the result for both unmarried and married couples, since thebest-fitting Model 1-7 shows no significant difference between unmarried and married
couples. The tendency for educational homogamy is found among couples with highschool or lower education and those with B.A. or higher education in both unmarried andmarried couples. The parameter estimates are 1.855 for homogamy of couples with highschool or lower education and 2.141 for couples with B.A. or higher education. Women
with some college education tend to marry either upward or downward for both partnershiptypes, and the likelihoods of hypergamy and hypogamy are the same (the parameter
estimate of 0.536). These results suggest that there is no differential structuring along
educational lines between married couples and unmarried couples.

US Analysis 2A: Dating Couples (A) and Cohabitating Couples (B)9Model 1-7 is statistically equivalent to Model 1-2. The reason we chose Model 1-7 over
1-2 is that Model 1-7 allows us to represent hypergamy and hypogamy as design matrix
even though the strengths of hypergamy and hypogamy are set identical.

The second set of analysis consists of two parts (US-Analysis 2A and 2B). The first part
(US-Analysis 2A) examines more detailed differences among unmarried couples by
disaggregating them into two partnership types: “Dating” or “Cohabitating.” Observed
frequencies are reported in Table 2B. The second part (US-Analysis 2B) compares thedifference in educational assortative mating between cohabitating couples and married
couples. We use the observed frequencies reported in Table 2A (married couples) andTable 2B (cohabitating couples) for US-Analysis 2B.

We first estimate Model 2A-1 as the baseline model for US-Analysis 2A. Table 4 gives thematrix form of this model.

Given the result from US-Analysis 1, we can reasonably

assume that the pattern of educational assortative mating among unmarried couples ischaracterized by a tendency for educational homogamy at the upper and lower levels of
education and by the tendency for heterogamy among women with a mid-level education.
Model 2A-1 sets as identical both the homogamy parameters for the upper and lower
education levels and the heterogamy parameters for women with some college education
across dating and cohabitating couples.

Model 2A-2 and Model 2A-3 can becharacterized as extensions of Model 2A.

Model 2A-2 adds a uniform-difference

parameter to Model 2A. Model 2A-3 allows each of the parameters in Model 2A-1 to varyacross the partnership types. Model comparison using fit statistics shows that Model 2A-2
is the best fitting model 10.

Figures 6A and 6B report the parameter estimates from the best-fitting Model 2A-2. Bothtypes of partnership show a very similar pattern of educational assortative mating. We
find in both figures that couples with high school or lower education and those with afour-year university education show a tendency for homogamy, and women with somecollege education show the same likelihood for both hypergamy and hypogamy. The bars
in Figure 6B are uniformly higher than those in Figure 6A.

The estimateduniform-difference (uni-diff) parameters imply that cohabitating couples (1.1323) exhibit auniformly stronger association than dating couples (1.0000). Unlike Analysis 1, Analysis
2A shows that there is a difference in the strength of couple formation between cohabitating
and dating couples, although the pattern of association is identical. It should be noted,

10Compared to Model 2A-1, Model 2A-2 provides a better fit to the data (L-square =2.666, df = 4, p = 0.615). The improvement in L-square is 4.801 with one degree of
freedom and is significant at the five percent level.

however, that the difference is not substantial (0.1323) despite its statistical significance.

US Analysis 2B: Cohabitating Couples (A) and Married Couples (B)We learned that cohabitating and dating couples differ with respect to their strength ofassociation. We would like to test whether cohabitating couples and married couples
show the same pattern and strength of association; to do this, we apply the same strategy
used in US-Analysis 2A. Comparison of the models using fit statistics shows that Model
2B-1 is the best fitting model. This model finds that there is no significant difference in thepattern and strength of association between cohabitating and married couples.

The

parameter estimate is 1.878 for homogamy at the lower educational level, 2.212 forhomogamy at the upper level, and 0.5737 for hypergamy and hypogamy among womenwith a mid-level education.

US-Analysis 3: Cohabitating Couples and Strong (A) or Weak Marriage Intention (B)US-Analysis 3 disaggregates cohabitating couples into two groups based on the differencein their intention to get married: cohabitating couples with a strong marriage intention andthose with a relatively weak intention. We follow the same procedure as for previous
analyses. Model 3-1 shows the best fit based on the fit statistics. This model assumes
no difference in educational assortative mating by marriage intention; both couples with astrong marriage intention and those with a weak intention show the same pattern andstrength of association.

The parameter estimates are 2.006 for the propensity ofhomogamy among couples at the lower education level and 2.196 for the propensity ofhomogamy among couples at the upper level.

There is a propensity (0.584) for

hypergamy and hypogamy in women with a mid-level education.

US-Analysis 4: Married Couples Living Together (A) and Those Separated (B)In the fourth set of analysis (US-Analysis 4), we disaggregate married couples into two
types: married couples who remained living together and those who became separated.
As in previous analyses, we follow the same procedure and apply the same set of models
to this data set. The results of model comparison indicate that Model 4-1 is the best fitting
model.

This model finds no significant difference in educational assortative mating

between the two types of married couples. The parameter estimates are similar to thosereported in Figure 5.

The result from Model 4-2 tells us that the uniform-difference

parameter estimates are 1.000 for married couples who remained living together and 0.917

for those who became separated.

This result is consistent with the notion that thestrength of association tends to be weaker for married couples who chose to separate, but
Model 4-2 is not significantly better than Model 4-1. Therefore, we have no evidence toclaim that the pattern and strength of educational assortative mating among married
couples are different when the couple no longer lives together.

By taking the results of the US analyses together, we conclude that the pattern of couples’
educational association is the same across all three types of partnerships: married,
cohabitating, and dating. However, the strength of association is slightly weaker among
dating couples than cohabitating or married couples.

Marriage intention among

cohabitating couples does not make a difference in the pattern or strength of association of
couples.

Living together or separately does not affect the pattern or strength ofassociation among married couples, either. By and large, we are impressed with theuniformity of the pattern and the strength in educational assortative mating across different
types of partnerships in the United States.

6. DISCUSSION AND CONCLUSION
This study 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 investigated the pattern of educational association among
unmarried couples. The most significant finding of our analysis is the difference in thepattern of educational assortative mating between married and courtship couples in Japan.
Educational homogamy at the top and the bottom of the educational hierarchy
characterizes the educational association among both unmarried and married partners.
However, educational levels of the couples show a more structured pattern among married
ones: there is apparently a stronger educational homogamy among married couples who
graduated from four-year universities and a propensity for women with junior college
educations to marry men with B.A. degrees.

With regards to the tendency of women’s hypergamy, it should be noted that women who
attended junior colleges but not technical schools (senmon gakko) are more likely to marrymen who graduated from four-year universities even though the attendants of both types ofschool are included in the “junior college” category. Junior colleges are predominantlyattended by women, and their graduates are known to have distinct advantage in themarriage market because of the reputation of being “good wiives and wise mothers”(Matsui 1997). The tendency of hypergamy among women with junior college educations
is probably supported by the persistent norm of gender division of labor in contemporary
Japanese society (Osawa 2011; Shirahase 2011, 2014).

In summary, unmarried couples seem to place less emphasis on the educational level of
their partners than married couples in the process of mate selection. 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 in selecting a courtship partner.
Japanese people may draw a clear distinction in mate selection procedure between
courtship and marriage. The overall results of the Japanese analyses are consistent withthe winnowing hypothesis. More stringent sorting criteria are used to select marriage
partners than unmarried partners. The importance of coupling of educational level of thepartners increases as couples move from courtship to marriage.

The comparison with American couples highlights cross-national similarities anddifferences between the two nations. In contrast to Japan, in the United States, the same
pattern of educational association characterized three types of couples: dating,cohabitation and married couples. Our results show that the pattern of association in the
United States resembles but not identical to that among married couples in Japan. First,
there is a strong tendency for people with B.A. degrees to form partnerships with theequally educated, and their level of educational homogamy is almost the same as
Japanese married couples. Second, at the lowest level of education, there is also atendency of educational homogamy: those with no more than a high school education tend
to form partnerships with the equally least educated.

The extent of homogamy issignificantly stronger than that found in Japan. The reason for their strong degree ofhomogamy derives from the fact that more than 40 percent of people with nopost-secondary education in the United States are high school dropouts.

The

corresponding figure in Japan is only seven percent. High school dropouts constitute thelowest level of educational attainment, and tend to have difficulty in finding partners withhigher levels of education. Those with high school diploma also tend to form partnershipwith those with a similar level of education, but the extent of homogamy is weaker than thatof high school dropouts. The difference in the composition of respondents with highschool or less category explains the cross-national difference in the degree of homogamy
among the least educated.

Third, women with AA degrees have a tendency of marrying up or forming partnership withthose with BA degrees in the United States. In addition, unlike Japan, women with somecollege have a tendency to find partners who have education lower than themselves.
Because women with some college are composed of those with AA degrees and those who
dropped out of the college, the two groups show two contradictory propensities (matchingwith partners with higher education and those with lower education). The presence ofboth hypergamy and hypogamy is related to the internal difference among the “somecollege” category in the United States. In Japan, very few college dropouts are in our
sample, and, as noted above, those who attended technical schools (not junior colleges)
do not show any tendency of hypergamy or hypogamy. The cross-national difference inthe composition of the mid-level educational category probably explains the presence of
hypogamy in the United States.

Regardless of the type of partnership, Americans appear to take serious account of theirpartners’ educational level.

Dating couples tend to show slightly weaker educational

association than other couples, but their association is clearly stronger than that foundamong unmarried couples in Japan. In the United States, there is a clear propensity tofind partners with the same level of education at the top and the bottom of the educational
hierarchy, and the difference between marriage mating and cohabitation matching is notclearly marked as far as partner’s educational association is concerned. Unlike Japan,
marriage partnership in the United States may not be clearly distinguishable from otherlong-term unmarried relationships.

Previous research in the United States shows acontinuous transition from pre-marital to marital stage. Manning and Smock (2002) claimthat the majority of cohabitation couples plan to marry their partners. Thornton, Axinn andXie (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” (emphasis
added).

Cohabitations tend to occur with clear plans for marriage.

Our data alsosuggest a similar finding; 26 percent of the Japanese married couples had experience of
cohabitation with their marriage partners prior to marriage, while 54 percent of theAmerican married couples had done so.

There is a much smoother transition fromcohabitation to marriage in the United States. The difference in the pattern of educational

assortative mating between pre-marital and marital couples in Japan may reflect a
discontinuous transition from courtship to marriage.

The discontinuous transition from courtship to marriage in Japan may be related to thepropensity of divorce. Divorce rates vary tremendously between the two nations. In
Japan, there is recent increase in divorce rate, but the rate is still relatively low: 1.87 per
1,000 population in 2011. The comparable figure in the United States is 3.40 in 2009
(Ministry of Health, Labour and Welfare 2013). The difference probably has implications
for people’s intention to enter into marriage. If it is hard to end a marriage, young people
are likely to be more cautious when selecting their marriage partner than they are about the
selection of a courtship partner. In short, we speculate that Japanese youth hold different
standards of mate selection for courtship than for marriage. In particular, for couples whoare highly educated, the cost of a “bad” marriage may be high. Since the 1980s, thedivorce rate has been consistently lower among people with higher education levels, while
the rate increased rapidly among those with the lowest level of education in Japan (Raymo,
Iwasawa, and Bumpass 2004; Raymo, Fukuda, and Iwasawa 2013). Divorce may not bea viable option for highly educated people, at least according to their expectations. The
cross-national differences in marriage persistence seem to have significant implications forthe transition from courtship to marriage in Japan and the United States.

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Figure 1. Trends in Arranged Marriage and Love Marriage from 1930 to 2009 in
Japan

Note:
・Horizontal axis represents years in which marriage took place.
・Vertical axis represents proportion of “Arranged Marriage” or Love “Marriage” to Total Marriages.

Figure 2. Analytical Framework for the Process of Transition from Courtship
Relationships to Marriage
Japan

Courtship
Relationships
Strong Intention

Courtship

Marriage
Weak Intention

Dissolution

United States

Courtship
Relationships
StrongIntention

DatingCohabitation

Marriage

Weak
Intention
Separation

Figure 3. Pattern of Educational Assortative Mating among Japanese Couples(JP-Analysis 1)
3A. Unmarried Couples

3B. Married Couples

Figure 4. Pattern of Educational Assortative Mating among Japanese
Unmarried Couples (JP-Analysis 2)
4A. Unmarried Couples – Relationship Continued

4B. Unmarried Couples – Relationship Dissolved

Figure 5. Pattern of Educational Assortative Mating among Couples in the
United States (US-Analysis 1)
Unmarried Couples and Married Couples

Note: Since we found no significant difference between unmarried couples and married couples, Figure 5
represents the pattern for both partnership types.

Figure 6. Pattern of Educational Assortative Mating among Unmarried
Couples in the United States (US-Analysis 2A)
6A. Dating Couples

6B. Cohabitating Couples

Table 1. Class-classification of Educational Levels of Female and Male Partners*1by Partnership Type in Japan
1A. Observed Frequencies for Unmarried and Married Couples
Unmarried Couples

Married Couples

Male
FemaleHigh School
Junior College B.A. or Moreor Less

Male
High School
Junior College B.A. or Moreor Less

FemaleHigh School or Less

58

20

38

High School or Less

558

197

216

Junior College

38

48

67

Junior College

419

340

572

B.A. or More

20

25

132

B.A. or More

74

66

535

1B. Observed Frequencies for Unmarried Couples who Continued their Relationships and Unmarried
Couples who Dissolved their Relationships
Unmarried Couples - Relationship Continued
FemaleMaleHigh School
Junior College B.A. or Moreor Less

Unmarried Couples - Relationship Dissolved
MaleHigh School
Junior College B.A. or Moreor Less

FemaleHigh School or Less

38

13

18

High School or Less

20

7

20

Junior College

25

27

45

Junior College

13

21

22

B.A. or More

12

12

91

B.A. or More

8

13

41

1C. Observed Frequencies for Unmarried Couples with Strong Marriage Intention and Unmarried
Couples with Weak Marriage Intention
Couples - Strong Intention

Couples - Weak Intention

Male
FemaleHigh School
Junior College B.A. or Moreor Less

FemaleMaleHigh School
Junior College B.A. or Moreor Less

High School or Less

29

10

16

High School or Less

9

3

2

Junior College

19

26

37

Junior College

6

1

8

B.A. or More

10

8

79

B.A. or More

2

4

12

*1 The dataset comes from the Japanese Life Course Panel Survey.

Table2. Class-classification of Educational Levels of Female and Male Partners
by Partnership Type in the United States *1
2A. Observed Frequencies for Unmarried and Married Couples
Unmarried Couples

Married Couples

Male

Male

FemaleHigh Schoolor Less

FemaleHigh Schoolor Less

Some College

B.A. or More

Some College

B.A. or MoreHigh School or Less

2060

579

142

High School or Less

1790

496

153

Some College

758

850

299

Some College

673

648

364

B.A. or More

200

405

681

B.A. or More

287

488

1405

2B. Observed Frequencies for Dating Couples and Cohabitating Couples
Dating Couples

Cohabitating Couples
Male

Male

FemaleHigh Schoolor Less

Some College

B.A. or More

FemaleHigh Schoolor Less

Some College

B.A. or MoreHigh School or Less

1241

422

109

High School or Less

819

157

33

Some College

512

644

232

Some College

246

206

67

B.A. or More

142

308

518

B.A. or More

58

97

163

2C. Observed Frequencies for Cohabitating Couples with Strong Marriage Intention and Cohabitating Couples
with Weak Marriage Intention
Cohabitating Couples - Strong Intention

Cohabitating Couples - Weak Intention

Male

Male

FemaleHigh Schoolor Less

FemaleHigh Schoolor Less

Some College

B.A. or More

Some College

B.A. or MoreHigh School or Less

472

101

24

High School or Less

347

56

9

Some College

171

161

54

Some College

75

45

13

B.A. or More

43

79

132

B.A. or More

15

18

31

2D. Observed Frequencies for Married Couples who Remained Living Together and Married Couples who Got
Separated
Married Couples who Remained Living Together

Married Couples who Got Separated

Male

Male

FemaleHigh Schoolor Less

Some College

B.A. or More

FemaleHigh Schoolor Less

Some College

B.A. or MoreHigh School or Less

1599

466

141

High School or Less

191

30

12

Some College

629

617

357

Some College

44

31

7

B.A. or More

278

480

1389

B.A. or More

9

8

16

*1 The dataset comes the National Survey of Family Growth 2006-2010.

Table 3. Specification of Interaction Parameters in Design Matrix Forms
for the Analyses of Japanese Couples*1 *2
Category A

Matrix = JP1

Category B

Male
FemaleHigh Schoolor Less

High School or Less
Junior College
B.A. or More

Male

Junior College

B.A. or More

FemaleHigh Schoolor Less100High School or Less

0

2

0

Junior College

0

0

3

B.A. or More

Category A

Matrix = JP2

Junior College

B.A. or More

4

0

0

0

5

0

0

0

6

Category B

Male

Male

FemaleHigh Schoolor Less

Junior College

B.A. or More

FemaleHigh Schoolor Less

Junior College

B.A. or MoreHigh School or Less

1

0

0

High School or Less

1

0

0

Junior College

0

2

0

Junior College

0

2

0

B.A. or More

0

0

3

B.A. or More

0

0

3

Category A

Matrix = JP3

Category B

Male

Male

FemaleHigh Schoolor Less

Junior College

B.A. or More

FemaleHigh Schoolor Less

Junior College

B.A. or MoreHigh School or Less

1

0

0

High School or Less

3

0

0

Junior College

0

0

0

Junior College

0

0

0

B.A. or More

0

0

2

B.A. or More

0

0

4

Category A

Matrix = JP4

Category B

Male

Male

FemaleHigh Schoolor Less

Junior College

B.A. or More

FemaleHigh Schoolor Less

Junior College

B.A. or MoreHigh School or Less

1

0

0

High School or Less

1

0

0

Junior College

0

0

0

Junior College

0

0

0

B.A. or More

0

0

2

B.A. or More

0

0

2

Category A

Matrix = JP5

Category B

Male

Male

FemaleHigh Schoolor Less

Junior College

B.A. or More

FemaleHigh Schoolor Less

Junior College

B.A. or MoreHigh School or Less

1

0

0

High School or Less

1

0

0

Junior College

0

0

0

Junior College

0

0

0

B.A. or More

0

0

2

B.A. or More

0

0

3

Category A

Matrix = JP6

Category B

Male

Male

FemaleHigh Schoolor Less

Junior College

B.A. or More

FemaleHigh Schoolor Less

Junior College

High School or Less

1

0

0

High School or Less

1

0

0

Junior College

0

0

0

Junior College

00

B.A. or More

0

0

2

B.A. or More

0

0

4
3

Category A

Matrix = JP7

Category B

Male

Matrix = JP8

B.A. or More

Male

FemaleHigh Schoolor Less

Junior College

B.A. or More

FemaleHigh Schoolor Less

Junior College

B.A. or MoreHigh School or Less

1

0

0

High School or Less

3

0

0

Junior College

0

0

0

Junior College

0

0

0

B.A. or More

0

0

2

B.A. or More

0

0

2

*3

Category A

Category B

Male

Male

FemaleHigh Schoolor Less

Junior College

B.A. or More

FemaleHigh Schoolor Less

Junior College

B.A. or MoreHigh School or Less

1

0

0

High School or Less

1*φ

0

0

Junior College

0

0

0

Junior College

0

0

0

B.A. or More

0

0

2

B.A. or More

0

0

2*φ

*1 Each number in a cell represents a distinctive interaction parameter within a design matrix.
*2 Cells sharing zeros are assigned no interaction parameters within the matrix.
*3 φ represents the uniform difference parameter.

Table 4. Specification of Interaction Parameters in Design Matrix Forms
for the Analyses of Couples in the United States*1 *2
Category A

Matrix = US1

Category B
Male

Male

FemaleHigh Schoolor Less

Some College

B.A. or More

FemaleHigh Schoolor Less

High School or Less

1

0

0

High School or Less

Some College

0

2

0

Some College

B.A. or More

0

0

3

B.A. or More

Category A

Matrix = US2

Some College

B.A. or More

4

0

0

0

5

0

0

0

6

Category B
Male

FemaleHigh Schoolor Less

High School or Less
Some College
B.A. or More

Male

Some College

B.A. or More

FemaleHigh Schoolor Less100High School or Less

0

2

0

Some College

0

0

3

B.A. or More

Category A

Matrix = US3

Some College

B.A. or More

1

0

0

0

2

0

0

0

3

Category B
Male

Male

FemaleHigh Schoolor Less

Some College

B.A. or More

FemaleHigh Schoolor Less

Some College

B.A. or MoreHigh School or Less

1

0

0

High School or Less

3

0

0

Some College

0

0

0

Some College

0

0

0

B.A. or More

0

0

2

B.A. or More

0

0

4

Category A

Matrix = US4

Category B
Male

Male

FemaleHigh Schoolor Less

Some College

B.A. or More

FemaleHigh Schoolor Less

Some College

B.A. or MoreHigh School or Less

1

0

0

High School or Less

1

0

0

Some College

0

0

0

Some College

0

0

0

B.A. or More

0

0

2

B.A. or More

0

0

2

Category A

Matrix = US5

Category B
Male

Male

FemaleHigh Schoolor Less

Some College

B.A. or More

FemaleHigh Schoolor Less

Some College

B.A. or MoreHigh School or Less

1

0

0

High School or Less

1

0

0

Some College

0

0

0

Some College

0

0

0

B.A. or More

0

0

1

B.A. or More

0

0

1

Category A

Matrix = US6

Category B
Male

FemaleHigh School or Less
Some College
B.A. or MoreHigh Schoolor Less

Male

Some College

B.A. or More

Female1300High School or Less

0

Some College

0

0

4
2

B.A. or More

Category A

Matrix = US7

High Schoolor Less

Some College

0

0

0

0

0

4
2

Category B
Male

FemaleHigh School or Less
Some College
B.A. or MoreMatrix = US8*3High Schoolor Less

Male

Some College

B.A. or More

Female1300High School or Less

0

Some College

0

0

3
2

B.A. or More

Category A

High Schoolor Less

Some College

High School or Less
Some College
B.A. or MoreHigh Schoolor Less

0

0

0

0

0

3
2

Category B
Male

Some College

B.A. or More

Female1300High School or Less

0

Some College

0

0

3
2

B.A. or More

Category A

Matrix = US9High Schoolor Less

Some College

1*φ
3*φ

0
0

0

0

High School or Less
Some College
B.A. or MoreHigh Schoolor Less

B.A. or More

0

3*φ
2*φ

Category B
Male

FemaleB.A. or More

1
3

Male
FemaleB.A. or More

1
3

Male

Some College

B.A. or More

Female1300High School or Less

0

Some College

0

0

3
2

B.A. or MoreHigh Schoolor Less

Some College

B.A. or More

4
6

0

0

0

0

0

6
5

*1 Each number in a cell represents a distinctive interaction parameter within a design matrix.
*2 Cells sharing zeros are assigned no interaction parameters within the matrix.
*3 φ represents a uniform difference parameter.

Table 5. Descriptive Statistics for Japanese Couples by Partnership Types *1
Unmarried Couples

Married Couples
Total

Total

Relationship Continued Relationship DissolvedHigh School or Less

0.353

0.260

0.267

0.248

Junior College

0.203

0.209

0.185

0.248

B.A. or More

0.444

0.531

0.548

0.503

High School or Less

0.326

0.260

0.246

0.285

Junior College

0.447

0.343

0.345

0.339

B.A. or More

0.227

0.397

0.409

0.376

Homogamous Couples (%)

0.534

0.481

0.555

0.497

Sample Size

2977

446

281

165

Male Partner's Educational Level (%)

Female Partner's Educational Level (%)*1 The dataset comes from the Japanese Life Course Panel Survey.

Table 6. Model Comparison using Fit Statistics for the Analyses of Japanese Couples
Model

Design Matrix

L-squared *1

D.F. *2

p-value

BIC *3

3.051

2

0.218

-13.225

9.701

5

0.084

-30.990

13.5894

0.009-18.964

17.1686

0.009-31.662

13.6145

0.018-27.078

2.184

4

0.702

-30.369

7.449

6

0.281

-29.153

4.387

5

0.495

-26.114

6.484

5

0.262

-24.018

4.330

5

0.503

-26.171

7.777

6

0.255

-26.054

6.809

5

0.235

-21.383

7.773

5

0.169

-20.419

7.252

5

0.203

-20.940

Analysis 1

Model 1-1
JP1
Model 1-2
JP2
Model 1-3
JP3
Model 1-4
JP4
Model 1-5JP5Model 1-6 *our best fitting model JP6
Analysis 2

Model 2-1
JP4
Model 2-2 *our best fitting model JP5Model 2-3
JP7
Model 2-4
JP8
Analysis 3

Model 3-1 *our best fitting model JP4Model 3-2
JP5
Model 3-3
JP7
Model 3-4
JP8
*1 L-squared stands for the Likelihood Ratio Chi-squared Statistics.
*2 D.F. stands for the degrees of freedom.
*3 BIC stands for Bayesian Information Criteria.

Table 7. Descriptive Statistics for Couples in the United States by Partnership Types*1
Unmarried Couples

Married Couples
Total

Total

Dating Couples

Cohabitating Couples

High School or Less

0.436

0.505

0.459

0.608

Junior College

0.259

0.307

0.333

0.249

B.A. or More

0.305

0.188

0.208

0.142

High School or Less

0.387

0.466

0.429

0.547

Junior College

0.267

0.319

0.336

0.281

B.A. or More

0.346

0.215

0.234

0.172

Homogamous Couples (%)

0.610

0.601

0.582

0.644

Sample Size

6304

5974

4128

1846

Male Partner's Educational Level (%)

Female Partner's Educational Level (%)*1 The dataset comes from the National Survey of Family Growth 2006-2010.

Table 8. Model Comparison using Fit Statistics for the Analyses of Couples in the United States
L-squared *1

D.F. *2

p-value

BIC *3

2.580

2

0.275

-16.251

5.734

5

0.333

-41.344101.76940.000

64.106103.72660.000

47.233131.8597

0.000

65.950

4.837

4

0.304

-32.825

5.734

5

0.333

-41.344

5.612

4

0.230

-32.050

2.580

2

0.275

-16.251

US7
US8
US9

7.467

5

0.188

-36.009

2.666

4

0.615

-32.114

2.376

2

0.305

-15.015

US7
US8
US9

4.089

5

0.537

-40.940

2.215

4

0.696

-33.808

0.829

2

0.661

-17.183

US7
US8
US9

1.692

5

0.890

-35.912

1.673

4

0.796

-28.410

0.962

2

0.618

-14.079

US7
US8
US9

5.373

5

0.372

-38.372

4.928

4

0.295

-30.067

1.611

2

0.447

-15.887

Model

Design Matrix

Analysis 1

Model 1-1
Model 1-2
Model 1-3
Model 1-4
Model 1-5
Model 1-6
Model 1-7 *our best fitting model
Model 1-8
Model 1-9

US1
US2
US3
US4
US5
US6
US7
US8
US9

Analysis 2A

Model 2A-1
Model 2A-2 *our best fitting model
Model 2A-3
Analysis 2B

Model 2B-1 *our best fitting model
Model 2B-2
Model 2B-3
Analysis 3

Model 3-1 *our best fitting model
Model 3-2
Model 3-3
Analysis 4

Model 4-1 *our best fitting model
Model 4-2
Model 4-3

*1 L-squared stands for the Likelihood Ratio Chi-squared Statistics.
*2 D.F. stands for the degrees of freedom.
*3 BIC stands for Bayesian Information Criteria.

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
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