Vanlaningham J., Johnson D. R. & Amato P., Marital Happiness, Marital Duration, And the U-Shaped...

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Social Forces, University of North Carolina Press Marital Happiness, Marital Duration, and the U-Shaped Curve: Evidence from a Five-Wave Panel Study Author(s): Jody VanLaningham, David R. Johnson, Paul Amato Reviewed work(s): Source: Social Forces, Vol. 79, No. 4 (Jun., 2001), pp. 1313-1341 Published by: Oxford University Press Stable URL: http://www.jstor.org/stable/2675474 . Accessed: 06/04/2012 11:08 Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at . http://www.jstor.org/page/info/about/policies/terms.jsp JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact [email protected]. Oxford University Press and Social Forces, University of North Carolina Press are collaborating with JSTOR to digitize, preserve and extend access to Social Forces. http://www.jstor.org

Transcript of Vanlaningham J., Johnson D. R. & Amato P., Marital Happiness, Marital Duration, And the U-Shaped...

Page 1: Vanlaningham J., Johnson D. R. & Amato P., Marital Happiness, Marital Duration, And the U-Shaped Curve - Evidence Form a Five-Wave Panel Study, Social Forces 79- 1313-41, 2001

Social Forces, University of North Carolina Press

Marital Happiness, Marital Duration, and the U-Shaped Curve: Evidence from a Five-WavePanel StudyAuthor(s): Jody VanLaningham, David R. Johnson, Paul AmatoReviewed work(s):Source: Social Forces, Vol. 79, No. 4 (Jun., 2001), pp. 1313-1341Published by: Oxford University PressStable URL: http://www.jstor.org/stable/2675474 .Accessed: 06/04/2012 11:08

Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at .http://www.jstor.org/page/info/about/policies/terms.jsp

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range ofcontent in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new formsof scholarship. For more information about JSTOR, please contact [email protected].

Oxford University Press and Social Forces, University of North Carolina Press are collaborating with JSTORto digitize, preserve and extend access to Social Forces.

http://www.jstor.org

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Marital Happiness, Marital Duration, and the U-Shaped Curve: Evidence from a Five-Wave Panel Study*

JODY VANLANINGHAM, University of Nebraska-Lincoln DAVID R. JOHNSON, University of Nebraska-Lincoln PAUL AMATO, Pennsylvania State University

Abstract

Previous research suggests a U-shaped pattern of marital happiness over the life course, with happiness declining in the early years of marriage and rising in the later years. Mostprior studies have been limited by the use of cross-sectional data or nonprobability samples. In contrast, the present study is based on data from a national, 1 7-year, 5- wave panel sample. Using cross-sectional data from the first wave, we replicate the U- shaped relationship between marital happiness and marital duration. In an analysis based on a fixed-effects pooled time-series model with multiple-wave panel data, we find declines in marital happiness at all marital durations and no supportfor an upturn in marital happiness in the later years. The relationship between marital happiness and marital duration is slightly curvilinear, with the steepest declines in marital happiness occurring during the earliest and latest years of marriage. When other life- course variables are controlled, a significant negative effect of marital duration on marital happiness remains. For most marriage cohorts, marital happiness declined more in the 1980s than in the 1990s, suggesting a period effect. This study provides evidence that the U-shaped pattern of marital happiness over the life course is an artifact of cross-sectional research and is not typical of U.S. marriages.

Since the first study of marital adjustment by Hamilton (1929), the manner in which marital happiness changes over the life course has been a major topic of interest among family scholars. Most studies suggest a U-shaped association characterized by high marital happiness in the early (or preparental) years of * This research was supported in part by Grant 5 ROI AG04146 from the National Institute on Aging. Direct correspondence to David R. Johnson, Department of Sociology, University of Nebraska, Lincoln, NE 68588-0324. E-mail: [email protected].

?C) The University of North Carolina Press Social Forces, June 2001, 78(4):1313-1341

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marriage, a decline in marital happiness during the middle (or parental) years, and a rise in marital happiness in the later (or postparental) years. Belief in this curvilinear pattern is widespread, and descriptions of the U-shaped curve are common in family textbooks (e.g., Cherlin 1996; Collins & Coltrane 1995; Gelles 1995). In a review of research on marital quality conducted during the 1970s, Spanier and Lewis (1980) reported strong support for the curvilinear pattern. And in a review of research on marital quality conducted during the 1980s, Glenn (1990) commented that "a curvilinear relationship between family stage and some aspects of marital quality is about as close to being certain as anything ever is in the social sciences" (33).

In spite of the widespread belief in a U-shaped association between marital duration (or stage) and marital happiness, a few studies suggest alternative patterns, with some showing a continuous decline in marital happiness, some showing a continuous increase in marital happiness, and some showing no significant association of any kind. For example, in a recent study, Glenn (1998) compared marital cohorts in repeated cross sections from the General Social Survey and found a pattern of continuous decline in marital success. Furthermore, the majority of studies that support the U-shaped curve contain serious methodological limitations, including the use of cross-sectional data to reach conclusions about change over time and the use of nonprobability samples to make inferences about the population of married individuals. Because of these limitations, we argue that the U-shaped association between marital happiness and marital duration has not yet been unequivocally demonstrated.

The present study attempts to clarify the manner in which marital happiness changes over the life course. To accomplish this goal, we draw on a national, 17- year, 5-wave panel study of married individuals. In the first step of our analysis, we use data from the initial wave of interviews to replicate previous cross-sectional studies. In the second step, we use pooled time-series models with multiple-wave data to gain a clearer picture of the association between marital duration and marital happiness, and we include a variety of life-course variables - such as the presence of children of various ages in the household - to see whether they explain the association. In the final step, we explore whether the association between marital duration and marital happiness varies with gender (husbands vs. wives), race (blacks versus nonblacks), and marriage cohort.

Review of Previous Research

CROSS-SECTIONAL STUDIES

A large number of cross-sectional studies suggest that marital quality declines in the early years of marriage and improves in the later years. In a typical study, Rollins and Feldman (1970) examined marital satisfaction in a sample of predominantly

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middle-class, white, one-earner couples in New York City. Based on marital duration, age of the oldest child, and residence of children, respondents were classified into one of eight stages of the family life cycle. The findings suggested that marital satisfaction declines steadily from the beginning of the marriage to the stage with school-age children, levels off as children grow into adolescence, and increases from the empty-nest stage to the retirement stage. Some other cross- sectional studies supporting the U-shaped association are Anderson, Russell, and Schumm (1983), Burr (1970), Condie and Doan (1978), Gilford and Bengtson (1979), Glenn (1989), Gurin,Veroff, and Feld (1960), Johnson et al. (1986), Lawson (1988), Lupri and Frideres (1981), Miller (1976), Peterson (1990), Rollins and Cannon (1974), Smart and Smart (1975), and Spanier, Lewis, and Cole (1975). More recent studies continue to replicate this result. For example, Orbuch et al. (1996) found a U-shaped association between marital satisfaction and marital duration in a large national sample. They also found that having children accounted for some of the apparent decline in satisfaction in the early years of marriage, whereas declines in work and parental responsibilities accounted for much of the apparent increase in marital satisfaction in the later years.

Not all cross-sectional studies, however, reveal a U-shaped association. In their study of 900 Detroit wives, Blood and Wolfe (1960) found a gradual decline in marital satisfaction throughout the child-rearing years, a slight rise after the launching of children, and a further decline through the years of retirement. More recently, Glenn (1998), using pooled data from the 1973-94 General Social Survey, found a U-shaped association between marital duration and marital success (being married and very happy) when the data were examined cross-sectionally. When the data were separated by marriage cohort, however, the relatively high level of success in marriages of long duration appeared to result largely from cohort differences, with older individuals having more successful marriages than younger individuals. Indeed, Glenn's analysis suggests that marital success declines sharply during the first ten years of marriage, then continues to decline, albeit more slowly, during the next forty years of marriage. Gilford (1984), Glenn and Weaver (1978), Hudson and Murphy (1980), and Medling and McCarrey (1981) have also failed to find the expected curvilinear association between marital satisfaction and marital duration using cross-sectional data. In spite of these exceptions, however, the majority of cross-sectional studies support the curvilinear pattern.

LONGITUDINAL STUDIES

Most longitudinal studies of marital quality show that marital happiness (or some related dimension of marital quality) declines in the first few years of marriage (Huston, McHale & Crouter 1986; Johnson, Amoloza & Booth 1992; Karney & Bradbury 1995; Kurdek 1998; Leonard & Roberts 1998; Lindahl, Clements & Markman 1998). Many of these studies begin with newlyweds, however, and most

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last less than ten years. Few studies have followed couples from the middle years of marriage into the later years. Consequently, most longitudinal studies have been unable to determine whether marital quality improves, flattens out, or continues to decline later in the marriage.

The few longitudinal studies that have followed couples from the middle to the later years of marriage do not provide a consistent picture. Weishaus and Field (1988) studied 17 couples married for fifty years or longer and found support for a curvilinear pattern, with a dip in positive affect during the middle years followed by a recovery. In contrast, Pineo (1961) followed 400 couples for twenty years and found a pattern of gradual but continuous "disenchantment." Similar results were reported by Johnson, Amoloza, and Booth (1992) in an eight-year study of individuals of various marital durations. In an eleven-year study of Mexican American families in San Antonio, Markides et al. (1999) found a decline in positive interaction for wives as they made the transition to old age but no corresponding change for husbands. Vaillant and Vaillant (1993) used retrospective and prospective forty-year data in their study of 104 men and their wives. They found support for the U-shaped trend using retrospective data but no support using longitudinal data. Existing longitudinal studies, therefore, fail to provide consistent support for an upturn in marital happiness in later life. Given the small number of studies and the inconsistent set of findings, additional longitudinal research is necessary to determine how marital happiness changes in the later years of marriage.

Theory

Drawing on a variety of perspectives, we outline three explanations for developmental change in marital happiness. Each of these perspectives makes somewhat different predictions about the association between marital duration and marital happiness. We use Featherman and Learner's (1985) definition of developmental change as mean changes in a group of individuals as they progress through the life course within a particular social and historical context.

CHANGES IN FAMILY ROLES AND STRUCTURE

The most widely used conceptual model for explaining the U-shaped trend in marital happiness focuses on changes in family roles and structures (Aldous 1978; Duvall 1977; Hill & Mattessich 1979; Rodgers 1964). Many studies have highlighted the apparent effect of adding and subtracting children (and the ages of children) on the quality of interaction between husbands and wives. These studies assume that children create demands on parents' time and income - demands that increase parents' feelings of stress and decrease the amount of time available to engage in shared leisure activities (Rollins & Galligan 1978; White, Booth & Edwards 1986). Indeed, many cross-sectional studies demonstrate that husbands and wives with

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children in the home report lower marital quality than do those without children (Houseknecht 1979; McLanahan & Adams 1989; Nock 1979; Renne 1970). If children create stress within marriage, then marital happiness should decline as children are added, decline even more as children move into the problematic adolescent years, and improve as the nest is emptied. Consistent with this notion, short-term longitudinal studies show that marital happiness declines following the first birth (Belsky, Spanier & Rovine 1983; Kurdek 1998; Leonard & Roberts 1998; Menaghan 1983) and increases when children leave the parental home (Menaghan 1983; White & Edwards 1990).

Although most studies have focused on children, other family changes, such as the movement of wives into and out of the paid workforce, changes in homeownership, increases (or declines) in family income, and retirement also represent transformations in family roles and structure that can affect individuals' evaluations of their marriages. For example, marital happiness might increase in the later years of marriage as couples become more financially stable, own their own homes, and enter retirement. Consistent with this notion, Lee (1989) found that decreases in responsibilities and role demands in the later years were associated with higher marital quality. Similarly, Myers and Booth (1996) found that retirement was associated with higher marital quality when husbands left high-stress jobs. Because these events are correlated with the duration of marriage, they are likely to account for much of the association between duration of marriage and marital happiness. Marriages that do not undergo these transitions would not be expected to undergo developmental change in marital quality.

SOCIAL PSYCHOLOGICAL AND INDIVIDUAL PROCESSES IN THE EARLY YARS OF MARRIAGE

It is apparent, both in the U.S. and elsewhere (Fisher 1992), that the emotional attraction between spouses generally peaks at the beginning of the marital union and declines over the next few years. The existence of a "honeymoon" effect is consistent with the family role and structure assumption that the addition of children increases stress in the marriage. Declines in marital happiness, however, also are apparent among childless couples (Belsky, Spanier & Rovine 1983; Lindahl, Clements & Markman 1998; McHale & Huston 1985; White & Booth 1985). Therefore, the decline in marital happiness during the first few years of marriage cannot be due solely to the addition of children to the household.

Social-psychological explanations for the early decline in marital happiness refer to interactional processes between spouses. Newly married couples are faced with many challenges, including establishing a division of labor, redefining ties to kin, and learning how to handle conflict in the relationship. Initial high expectations at the formation of the union may become tempered by the realities of married life. Booth (1999) and Glenn (1996) argue that newlyweds' expectations are unrealistically high, with many individuals assuming that marriage will be a

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continuous source of personal fulfillment and self-actualization - an expectation that most marriages cannot meet. This problem is exacerbated if individuals hide some of their faults from their future spouses prior to marriage, resulting in a process of gradual disillusionment after the wedding (Huston & Houts 1998). Another explanation is based on the assumption that people exhibit individual changes in attitudes, values, and life-style preferences throughout the life course. Pineo (1961) has argued that spouses usually marry at the time when they are most compatible with one another. But as time passes, individuals experience gradual, random changes that lead to a "poorer fit." Such a tendency is consistent with exchange theory (Sabatelli & Shehan 1993), which assumes that the marital exchange is based on valued characteristics that each partner brings to the marriage. These characteristics are likely to change over time, disrupting the equity of the exchange and resulting in a decline in marital happiness.

From the perspective of individual psychology, declines in marital happiness may reflect habituation to the relationship. Behavioral psychologists have demonstrated that individuals gradually habituate - psychologically and physiologically - to a repeated stimulus (Lowe et al. 1985). Call, Sprecher, and Schwartz (1995) used habituation (among several other factors) to account for the decline in the frequency of sexual activity among married couples over time. The decline in marital satisfaction may have a biological foundation in the brain chemical phenylethylamine (or PEA), which has been associated with feelings of well-being and the "high" following a new romantic relationship (Fisher 1992). The decline in happiness may occur either because neurons become habituated to the effects of PEA or because levels of PEA decline over time.

In contrast to explanation based on changes in family roles and structures, social-psychological explanations assume that the decline in marital happiness in the early years of marriage reflects intrinsic aspects of the evolving marital relationship - developments that are largely independent of role and structural changes. Similarly, psychological and physiological explanations place the locus of change entirely within the individual. If these models are correct, then we should observe a sharp decline in marital quality over the first few years of marriage, net of changes such as the addition of children. Furthermore, unlike the family role and structure perspective, social-psychological and individualistic models do not predict an upturn in marital happiness in the later years of marriage. Instead, these perspectives suggest a stabilization of marital happiness after the first few years, albeit at a lower level than when the marriage began.

PERIOD AND COHORT EFFECTS

Period effects also may play a role in explaining the link between marital duration and marital happiness. According to this view, shifts in marital happiness may not reflect intrinsic marriage processes as much as they reflect changes in the larger

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social and economic environment of married couples in recent decades. For example, many marriages, regardless of duration, have been affected by the erosion of men's real wages since 1973. Economic hardship due to men's declining income has been linked to marital discord and more problematic family relationships (Conger & Elder 1994; Voydanoff 1988). In addition, the potential for work-family conflict has increased with the rise in labor-force participation among married mothers of young children. In 1960 only 19% of married mothers with preschool children were in the labor force, compared with 65% in 1995 (Spain & Bianchi 1996). Numerous observers have documented the potential for the conflicting demands of work and family to create stress for parents - stress that often spills over and affects the quality of marital relations (Booth et al. 1984; Voydanoff 1988).

Changes in gender relations in the larger society also may create stress within particular marriages. Both women and men - but particularly women - have become less traditional in their gender attitudes since the late 1960s (Thornton 1989). In a longitudinal study, Amato and Booth (1995) found that wives who adopted more egalitarian attitudes became less satisfied with their marriages and reported greater discord. Presumably, wives who adopt nontraditional views must negotiate work and family responsibilities with their husbands that previous cohorts of wives took for granted, thus raising the potential for tension in the relationship. The household division of labor, in particular, has became contentious in many marriages. Research consistently documents the fact that husbands perform less housework and child care than wives, even when wives are employed full-time (Hochschild 1989; Robinson & Godbey 1997). The perception that the household division of labor is unfair is a cause of conflict in many marriages (Hochschild 1989; Pina & Bengtson 1993). Moreover, increases in wives' earnings and growing beliefs about gender equality have encouraged wives to press for more decision- making power, thus challenging the status quo and generating conflict with husbands (Thompson 1991).

Furthermore, some scholars believe that there has been a growth of individualistic values in U.S. culture (Bellah et al. 1985; Glenn 1996; Popenoe 1988). Because divorce is readily available, individualistic spouses may invest relatively little effort in resolving disagreements, thus eroding relationship quality and stability (Amato & Rogers 1999). Because the larger social environment has become less hospitable to marriage, some declines in marital quality observed within recent longitudinal studies may reflect period effects rather than developmental processes intrinsic to the marriage.

Correspondingly, the "improvement" in marital quality in the later years often observed in cross-sectional studies may reflect intercohort differences rather than developmental changes. Specifically, older individuals in longer-duration marriages and younger persons in shorter-duration marriages represent different marriage cohorts. Marriages among individuals from older cohorts occurred within a more

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traditional context - with a lower divorce rate, more social support for marriage, and a greater commitment to the norm of lifelong marriage - than have more recent marriages. For this reason, older individuals from earlier marriage cohorts may have higher (and relatively stable) levels of marital quality than more recent marriage cohorts. These intercohort differences would appear as a rise in happiness in the later years of marriage in cross-sectional data - a prediction consistent with Glenn's (1998) analysis.

Contributions of the Present Study

The preponderance of evidence appears to support a curvilinear association between marital duration and marital happiness. Some studies, however, suggest alternative patterns. These discrepancies may be due to the fact that most studies in this literature are based on nonprobability samples drawn from narrow geographic areas or from specific demographic groups. Differences between samples make it difficult to compare findings and to generalize the results to larger populations. The most troublesome aspect of this literature, however, is its extensive reliance on cross- sectional data, which cannot distinguish developmental trends from intercohort differences. Also, married individuals in older cohorts represent a select group of marriages that have survived, with unhappy marriages that ended in divorce being selected out of the population of married persons. Consequently, in a cross-sectional sample, apparent increases in marital happiness in the later years of marriage may reflect compositional differences due to the departure of the most unhappily married couples from the sample through divorce. Addressing this issue, Glenn (1990) concludes that "cross-sectional data from a sample of married persons are not, strictly speaking, appropriate for a causal analysis in which marital quality is the dependent variable" (820).

To address some of the methodological limitations of prior research, the study presented here attempts to determine the pattern of marital happiness over the life course through a comprehensive analysis of 5-wave, 17-year panel data from a nationally representative sample of married individuals. We begin with a cross- sectional analysis using the first wave of interviews to replicate the U-shaped association revealed in most previous studies. We then conduct a longitudinal analysis using the 5-wave, 17-year data. The longitudinal analysis expands on the findings of Johnson, Amoloza, and Booth (1992), which indicate developmental change in marital happiness in the first three waves (8 years) of the same data set. The present study uses a fixed-effects pooled time-series model to determine more specifically the pattern of change.

The explanatory perspective based on family roles and structures predicts that the longitudinal association between marital duration and marital happiness forms a U-shaped curve. This perspective further predicts that much of the curve will

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"disappear" with appropriate controls for changes in family roles and structure, such as the addition or subtraction of children from the household. In contrast, perspectives based on dyadic processes (such as disillusionment) or individual processes (such as habituation) predict a downward trend in marital happiness in the first few years of marriage followed by stabilization with no resurgence in the later years. A perspective based on period effects also predicts a downward trend in marital happiness - not only because of intrinsic relationship processes but also because couples have been exposed to an economic and social environment in recent decades that is unsupportive of marriage. Indeed, an explanation based on period effects (unlike an explanation based on dyadic or individual processes) suggests the possibility of a decline in happiness extending beyond the first few years of marriage. A more or less continuous decline may occur because marital problems that have their origins in larger social conditions (such as declines in men's income, work-family conflict, disagreements over gender roles, and growing individualism) are unlikely to abate as long as these social conditions remain unchanged. Finally, a cohort perspective assumes that a curvilinear trend will appear in cross-sectional data but not in longitudinal data. Of course, explanations based on dyadic processes, habituation, and period and cohort effects are not mutually exclusive, and it may not be possible to distinguish between them in any one study. Nevertheless, these perspectives (which predict no upward trend in happiness in the later years of marriage) contrast sharply with the more widely accepted family role and structure perspective, which predicts an upward trend in happiness in the later years of marriage.

Methods

DATA

The data for this study are from the Marital Instability over the Life Course study, a five-wave panel study of a national sample of married persons followed over 17 years (Booth et al. 1999). Respondents were interviewed by telephone in 1980, 1983, 1988, 1992, and 1997. During the first wave of the study, random digit dialing was used to select a sample of married individuals aged 55 and under. Among eligible households, the interview completion rate for the initial wave of the study was 65%, yielding a sample size of 2,034. The response rates for the reinterviews were 78% in 1983, 84% in 1988, 89% in 1992, and 88% in 1997. When compared with national data, the original sample was found to be representative of the U.S. population with respect to age, race, household size, presence of children, housing tenure, and region, although residents of large metropolitan areas were slightly underrepresented (Booth & Johnson 1985). We evaluated whether persons from unhappier marriages were more likely to leave the study than those from happier marriages. In an event-history analysis, neither marital happiness in 1980 nor that

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in the wave immediately preceding the attrition (a time-varying covariate) was significantly related to attrition through the fifth wave of the study. A hazard model of persons in the first three years of marriage in 1980 (the group least likely to be affected by left-censuring bias) estimated a 12-year marital disruption rate of 35% (Johnson & Booth 1998), which is similar to national rates for this cohort (Sweet & Bumpass 1987). We conclude that the impact of selection bias due to attrition on the relationship between marital duration and marital happiness is minimal in these data.

We used two data sets from the larger study. The first consisted of the cross- sectional data from the first wave. The second data set was based on pooled data from all five waves. The pooled sample included all respondents who were in intact marriages (and married to the same spouse) for at least two waves of the study and for whom complete information was available on the measures used in this analysis. (We included data from individuals who remarried during the course of the study.) In this data set, each individual had as many records as waves meeting the above criteria. The resulting sample comprised 1,479 individuals representing 1,530 separate marriages. The total size of the pooled sample was 5,932, and the average number of waves per respondent was 3.88.

MEASUREMENT

Marital Happiness

Marital happiness was measured with an 11-item scale reflecting people's feelings toward various aspects of the marital relationship. Specifically, respondents were asked to report their degree of happiness with (1) the amount of understanding received from their spouse, (2) the amount of love and affection received, (3) the extent to which they and their spouse agree about things, (4) their sexual relationship, (5) their spouse as someone who takes care of things around the house, (6) their spouse as someone to do things with, and (7) their spouse's faithfulness to them. Responses to these items ranged from 1 ("very happy") to 3 ("not too happy"). Respondents also were asked the following: (1) "Taking all things together, how would you describe your marriage? Would you say that your marriage is very happy, pretty happy, or not too happy?" (2) "Compared to other marriages you know about, do you think your marriage is better than most, about the same as most, or not as good as most?" and (3) "Comparing your marriage to three years ago, is your marriage getting better, staying the same, or getting worse?" The final item asked respondents to rate their feelings of love for their spouse, ranging from 1 ("extremely strong") to 5 ("not strong at all"). This item was recoded to a three-point range (1, 1.5, 2, 2.5, 3) to be consistent with the other items. With all items coded so that a high score indicated greater marital happiness, scores on the summated scale ranged from 11 to 33. The mean score for respondents in the first wave of the panel study was 28.50 with a standard deviation of 4.01. The multiple-wave panel sample

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used in the second stage of the analysis yielded a mean score of 28.11 with a standard deviation of 4.15. This measure was reliable with Cronbach's alphas of .87, .84, .88, .89, and .88 in the five panel waves.

Marital Duration

Marital duration was included as a continuous variable, measured by the number of years the respondent was married at the time of the interview. Respondents in the 1980 sample (used in the cross-sectional analysis) had marriages ranging from 0 to 38 years in duration, with a mean of 12.50 years and a standard deviation of 9.13. Marital duration among respondents in this sample was truncated at 38 years because only adults who were under age 55 in 1980 were included in the sample. The pooled sample used in the second stage of the analysis included marriages ranging in duration from 0 to 54 years, with a mean length of 19.31 and a standard deviation of 10.80.

Control Variables

The cross-sectional analysis of 1980 data included a set of variables to control for the effects of social and demographic factors. These variables included gender, race, and education. Gender and race were both included as dichotomous terms (O = male, 1 = female; 0 = not black, 1 = black). Education was included as a continuous variable measured in years.

Additional variables were included in the pooled time-series analysis. The fixed- effects model employed in this analysis controlled for all time-invariant differences between individuals, both observed and unobserved (Allison 1994; Jasso 1985). Consequently, social background variables that are time-invariant or nearly so (such as educational attainment) were not included in this model. However, we included variables that may change over the life course and affect marital happiness. These variables include family income, homeownership, ages and number of children in the household, and retirement. Income was measured in dollars and was adjusted for cost-of-living differences between the waves by expressing them in 1997 dollars. Individuals with missing data on the income variable were assigned the mean, and a dummy variable (coded 1 for cases missing data on income and 0 for all others) also was included. Homeownership was coded 0 for renters and 1 for those who owned or were buying their home at the time of the interview. A set of five variables was included to represent the number of children in certain age ranges present in the household at the time of the interview. The age ranges were infants (under age 2), preschoolers (aged 2-5), school-age children (aged 6-12), teenagers (aged 13-18), and adult children (aged 19 and over). Retirement status was indicated by a 1 if the husband was retired at the time of the interview and 0 otherwise.

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ANALYSIS

The cross-sectional model is based on ordinary least-squares regression analysis, while the pooled time-series data were analyzed with a fixed-effects pooled time- series model. These latter estimates were calculated using the procedures in STATA (StataCorp 1999). The fixed-effects pooled time-series statistical model has been used widely by econometricians to analyze panel data, but it has received more limited attention in the field of sociology (Allison 1994), although there have been several recent applications of fixed-effects models to family data (Cherlin, Chase- Lansdale & McRae 1998; Lichter, McLaughlin & Ribar 1997; Nock 1998; see Johnson 1995 for a comparison of pooled time-series models to other methods routinely used in the quantitative analysis of panel data in family research).

The fixed-effects pooled time-series method has been shown to be effective in estimating the effects of events or other time-varying factors on individual outcomes, as well as in addressing developmental patterns with a continuous dependent variable (Allison 1994; Johnson 1995). The technique has several advantages that make it especially well suited for analyzing the longitudinal data in this study. These advantages include (1) the ability to analyze data from all five waves of the panel study, even though the time intervals between the waves of data collection were not equal; (2) the ability to include respondents with data from two, three, four, and five waves of the panel study; and (3) the ability to obtain unbiased estimates of change over time, as measured by marital duration. Because all time-invariant influences, both observed and unobserved, are implicitly controlled in the fixed-effects model, the model's estimates are independent of the effects of birth cohort, marriage cohort, selection bias, and all other time-invariant differences between individuals.

Results

CROSS-SECTIONAL ANALYSIS OF 1980 DATA

Descriptive statistics for the variables included in the cross-sectional analysis of the 1980 wave of panel data are presented in Table 1.

Figure 1 shows the relationship between marital happiness scores and marital duration in the cross-sectional (wave 1) sample. We plotted the shape of the curve with Lowess (locally weighted scatterplot smoother). Lowess fits a smoothed curve based on a set of regressions for each observation that use a proportion of the observations closest to the x value (we used .35). The technique also includes a procedure to reduce the impact of outliers (Fox 1991). The smoothed curve reproduced the classic U-shaped curve found in many cross-sectional studies. Happiness levels were high for short-duration marriages, reached their lowest level

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TABLE 1: Descriptive Statistics for Mriables Included in 1980 Cross-Sectional and Pooled Time-Series Data

Variable Mean S.D. Range

Cross-sectional 1980 data

Marital happiness 28.50 4.01 11.5-33.0 Years married 12.50 9.13 0-38 Gender (1 = female) .60 .49 0-1 Race (1 = black) .05 .21 0-1 Education 13.44 2.61 0-25

(N= 1,966)

Pooled time-series data

Maritalhappiness 28.11 4.15 11-33 Marital duration (in years) 19.31 10.80 0-54.43 Income 53,303.67 23,079.95 2,500-125,359 Income-missing indicator .02 .15 0-1 Homeownership (O = rent) .89 .33 0-1 Retirement (1 = husband retired) .05 .22 0-1 Number of children in household

Infants .08 .29 0-2 Preschoolers .22 .51 0-4 School-age .33 .47 0-2 Teenagers .37 .66 0-4 Adult children .27 .59 0-5

(N= 5,932)

in marriages of 15-18 years' duration, and gradually increased after 20 years of marriage.

We next used three regression models with duration treated as a continuous variable to explore this U-shaped curve and determine whether it held up after controlling for several background variables. In model 1 in Table 2, we found no significant linear relationship between marital duration and marital happiness. Model 2 added years married squared to the equation and confirmed the presence of a significant (p < .01 ) quadratic relationship. A model (not shown here) with a cubic term was also tested but was not statistically significant. This quadratic relationship (also plotted in Figure 1) corresponded closely to the Lowess smoothed curve. In model 3 we added controls for race, gender, and education. While race and gender were significantly related to marital happiness (with blacks and wives reporting less marital happiness than nonblacks and husbands, respectively), the curvilinear association between marital duration and marital happiness remained

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FIGURE 1: Marital Happiness by Marital Duration for 1980 Sample: Lowess and Quadratic Curves

32 -

Lowess Quadratic

?) 30 - c

I

a 28

26-

0 10 20 30 40 Number of years married to current spouse

essentially unchanged. The overall association between marital happiness and marital duration was not strong and accounted for less than 1% of the variance in model 2. However, the difference between individuals at the lowest and highest points of the curve represented about one-fourth of a standard deviation in marital happiness, suggesting a moderate difference between these key groups (Cohen 1988). More important, the pattern is consistent with the results of previous cross- sectional studies. The next step was to assess whether this pattern held using longitudinal data.

LONGITUDINAL ANALYSIS OF THE MULTIPLE-WAVE PANEL DATA

Descriptive statistics for all of the variables included in the pooled time-series analysis of the panel data are reported in Table 1.

The results of five models, based on fixed-effects pooled time-series regression analyses, are presented in Table 3. The first three models evaluated the type of curve that fits the association between marital duration and marital happiness. Model 1 showed a significant linear decline in marital happiness with marital duration (f3 = -.076, p < .001). A test for a quadratic relationship in model 2 was also statistically significant (p < .001), as was the cubic term in model 3 (p < .001). The curve implied by model 3 is plotted in Figure 2. The curve shows a relatively

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TABLE 2: Unstandardized Coefficients for Regression of Marital Happiness on Marital Duration in 1980 Cross-Sectional Sample

Marital Happiness

Independent Variables Model 1 Model 2 Model 3

Years married -.0100 -.0275* -.0258* Years married2 .0038** .0036** Race (1 = black) -1.6984** Gender (1= female) -.7810** Education .0340

Constant 28.6232 28.5234 26.9100 R2 .0005 .0062 .0250 * p <.05 **p <.01

steep initial decline in marital happiness with a gradually flattening, but still declining, slope until around 40 years' duration. After 40 years of marriage, the slope declines more steeply. While significantly curvilinear, it is clear that this pattern does not reproduce the U-shaped curve found in the cross-sectional data.

In the next two models we evaluated whether socioeconomic and life-course factors accounted for the observed pattern. Model 4 added the economic factors, and model 5 added the number of children, in five age categories, present in the household. None of the economic variables (including income, homeownership, and retirement) was significantly related to marital happiness. The presence of children in the household was significantly related to marital happiness. For all five age categories, the number of children was negatively associated with marital happiness. These effects were statistically significant, however, only for preschoolers, teenagers, and adult children living in the household. With these controls included, each of the marital duration terms remained significant, although the shape of the curve (also plotted in Figure 2) changed somewhat. The main effect of adding the variables related to children was to reduce the rate of decline in the first 25 years of the marriage. This result indicates that the presence of children accounted for some of the decline in marital happiness during the first 25 years of marriage but did not account for the more general decline over the course of the entire marriage. For example, an adult child departing from the household at 25 years' duration would increase marital happiness by .39 points. But after 7 years, the general trend toward lower marital happiness would eliminate the gain in happiness associated with the departure of the adult child.

The sample analyzed in Table 3 included marriages that dissolved during the course of the panel. In these marriages, we would expect to find a decline in marital happiness as the marriage approaches its end (Johnson & Booth 1998). Consequently, these marriages could account for the observed decline with

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TABLE 3: Unstandardized Coefficients for Fixed-Effects Regression of Marital Happiness on Marital Duration in Pooled Time-Series Analysis of Five-Wave Panel Data

Marital Happiness

Independent Viriables Model 1 Model 2 Model 3 Model 4 Model 5

Marital duration -.0760*** -.1264*** -.2845*** -.2878*** -.2415*** Marital duration2 .0019*** .0088*** .0089*** .0068*** Marital duration3 -.0001*** -.0001*** -.00008**

Income (in thousands) .0017 .0020 Income-missing indicator .0303 .0013 Homeownership

(0 = rent) .0829 .1118 Retirement

(1 = husband retired) -.1824 -.1820

Number of children in household

Infants -.1793 Preschoolers -.2624** School-age -.1870 Teenagers -.2562*** Adult children -.3771***

Constant 29.581 29.425 30.706 30.571 30.688 R2 .0275 .0335 .0386 .0388 .0450

(N = 1,530 individuals, 5,932 records)

** p < .01 *** p < .00 1

duration. It is possible that the association between marital happiness and marital duration looks somewhat different if we consider only marriages that remain continuously intact. To test for this possibility, we repeated the fixed-effects pooled time-series regression models including only those persons who were continuously married to the same spouse during the 17-year duration of the study. This procedure reduced the sample to 736 individuals and 3,680 records. These results are presented in Table 4.

The pattern of findings for continuously married persons was similar to that observed for the larger sample that included marriages that dissolved. Compared with the models in Table 3, the models in Table 4 explained slightly less of the variance in marital happiness, and the significance levels were generally lower (which partly reflects the smaller sample). The major difference is that children appeared to have a stronger effect, with four of the five child variables being statistically significant. When the child variables were included in the equation, the relationship between duration and marital happiness was no longer curvilinear

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FIGURE 2: Marital Happiness by Marital Duration from the Fixed-Effects Models

31

- No Controls (Model 3) 30

- - - All Controls (Model 5) 29-

I 28

Z 27

26 - v

25 0 5 10 15 20 25 30 35 40 45 50

Marital Duration in Years

but retained a significant negative linear trend. We conclude that the general finding that marital happiness declines continuously with marital duration is true for the set of marriages for which a divorce in the future is unlikely.

We next examined the data to see whether the pattern of decline varied with gender or race. We computed two multiplicative terms, one to test for the interaction between marital duration and gender (husbands vs. wives) and the other to test for the interaction between marital duration and race (black versus not black). These terms were added separately to the fixed-effects models. Neither term was statistically significant, suggesting that the decline in marital happiness was similar for husbands and wives and for blacks and nonblacks.

We then plotted marital happiness scores over the 17 years of the panel for seven marriage cohorts defined by the year of the marriage. Each cohort except the last encompassed a five-year range, starting with the most recent cohort - those married between 1976 and 1980 - and ending with those married before 1951. We confined the sample for this analysis to persons continuously married to the same partner during the study and with complete data for all five waves. We plotted each marriage cohort with a separate Lowess curve and report these in Figure 3. The curve for each cohort except the last extends through 22 years of marriage (five years for the range of the group plus 17 years for the length of the study), and

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TABLE 4: Unstandardized Coefficients for Fixed-Effects Regression of Marital Happiness on Marital Duration: Continuously Married Persons Only

Marital Happiness Independent Variables Model 1 Model 2 Model 3 Model 4 Model 5

Marital duration -.0578*** -.1240*** -.1994*** -.2038*** -.1236** Marital duration squared .0016*** .0056** .0057** .0021 Marital duration cubed -.000061* -.00006* -.00002

Income (in thousands) .0017 .0022 Income-missing indicator .5521 .5921 Homeownership

(0 rent) .0730 .1123 Retirement

(1 = husband retired) -.2400 -.2071

Number of children in household

Infants -.1474 Preschoolers -.2551* School-age -.3447** Teenagers -.2930*** Adult children -.3929***

Constant 29.688 30.220 30.530 30.403 30.403 R2 .0219 .0271 .0287 .0298 .0385

N = 736 individuals, 3,680 records

* p <.05 ** p <.01 *** p <.001

each line begins at 1980. The oldest cohort extends over a longer period of time because its range is larger (it includes marriages from 30 to 38 years' duration in 1980). Each person in the sample was represented by five data points in the figure (one for each wave). The number of persons in each cohort respectively were 114, 165, 118, 99, 113, 73, and 24.

The patterns observed in Figure 3 confirm some of the findings from the fixed- effects analysis and provide additional insights. First, there is little consistent evidence of a change in marital happiness in the form of a U-shaped curve. Only two of the cohorts (1961-65 and 1971-75) showed an upturn in the latest duration observed, and these changes were small. The other cohorts followed a general pattern of decline. Second, there was evidence of a period effect, with sharp declines in happiness during the 1980s and only modest declines in the 1990s. Five of the seven cohorts showed declines in the early to mid- 1980s, with the largest occurring in the 1976-80, 1966-70, and 1950 or earlier cohorts. Third, there was evidence of a cohort effect. With a few exceptions, in the durations in which the curves

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FIGURE 3: Marital Happiness by Marital Duration for Seven Marital Cohorts

34-

1 976-80 32 -

uz / 1 971-75 1 956-60 a)

CLl 1 966-70 | 195 1-55 CL

I 50 or earlier

ci

28

26

0 20 40 60 Marital Duration in Years

overlapped, the more recent cohorts had lower average marital happiness scores. A notable exception was in the oldest marital cohort, which started well above the other cohorts but by the end of the observation period was well below the two adjacent cohorts. We temper any substantive interpretation of this older cohort because of the relatively small sample size (24) in this group.

To evaluate whether the general decline observed in the fixed-effects analysis shown in Figure 2 reflected the presence of a period decline in the early to mid- 1980s (rather than a general developmental process extending into the later years of marriage), we repeated the pooled time-series analysis reported in Table 3, confining the analysis to the 1988, 1992, and 1997 waves of data. This analysis excluded the two periods (1980 and 1983) that showed the greatest decline in marital happiness scores. The sample size for this analysis was reduced because only persons with two or more waves of observations could be retained. Another limitation was that persons with marriages of less than 8 years' duration were represented only by those respondents who remarried and were in the study long enough to report on the marital happiness of the new marriage in two of the three waves. The replication of the fixed-effect regression models for this group is reported in Table 5.

The results from this truncated sample were similar to those based on all five waves of the panel. The explained variance was substantially lower, reflecting the loss of data in 1980 and 1983, when much of the decline in marital happiness

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TABLE 5: Fixed-Effects Models of Marital Happiness Including Data from the Three Waves from 1988 to 1997 Only

Marital Happiness

IndependentViriables Model 1 Model 2 Model 3 Model 4 Model 5

Marital duration -.0184 -.1026** -.3116** -.3065** -.2718** Marital duration2 .0017* .0115** .0110** .0086* Marital duration3 -.0001 -.0001* -.0001

Income (in $1,000s) .0001 .0001 Income-missing indicator .6367 .6821 Homeownership

(0 = rent) .3527 .3882 Retirement

(1 = husband retired) -.6007* -.5596

Number of children in household

Infants -.3532 Preschoolers -.4118* School-age -.5313* Teenagers -.2849* Adult children -.4520**

Constant 28.471 29.313 30.469 29.687 30.216 R2 .0010 .0042 .0083 .0131 .0232

(N = 1,028 individuals, 2,834 records) * p <.05 ** p <.01

occurred. The curves reflecting these equations are plotted in Figure 4. (We plotted models 3 and 5 only.) The results show a substantial decline until around 20 years of marriage followed by a flat association in later durations. The U-shaped curve was not evident either before or after controls were introduced. The range of change in marital happiness was reduced in this analysis, however, compared with the range estimated in the models that included the 1980 and 1983 waves of data (compare Figure 4 with Figure 2). This result suggests that the continued decline in marital happiness at longer durations observed in the full sample may reflect a period effect, that is, declines in the 1980s that did not persist into the 1990s.

Discussion

The assumption that marital happiness declines during the early years of marriage, stabilizes during the middle years, and then increases again in the later years is widely accepted among family scholars and is reported in many textbooks. Support

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FIGURE 4: Marital Happiness by Marital Duration (1988-97 waves only)

31

30 No controls X \^ - - - All Controls a) 29

.5_

L 27

26

25 0 5 10 15 20 25 30 35 40 45 50

Marital Duration in Years

for this model, however, is largely based on cross-sectional studies. Many of these studies are limited further by reliance on small, regional, nonprobability samples from specific demographic groups. In contrast, our results are based on a large, national, 17-year panel study. Contrary to previous research, our findings do not support a U-shaped pattern of marital happiness over the life course. Although the U-shaped association was replicated in the analysis of cross-sectional data, no evidence for such an association appeared in the panel data. Instead, our longitudinal analysis suggests that marital happiness either declines continuously (Figure 2) or flattens after a long period of dedine (Figure 4). We find little evidence that happiness increases in the later years of marriage. It appears, therefore, that the U-shaped pattern is largely an artifact of using cross-sectional data.

A pattern of gradual decline in marital happiness clashes with the central prediction of the family role and structure perspective. Nevertheless, our analysis indicates that certain life-course transitions, primarily those involving changes in the number of children at various ages, are associated with changes in marital happiness. Consistent with a large number of previous studies, our results show that the presence of children - regardless of age - is associated negatively with

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marital happiness (Belsky, Spanier & Rovine 1983; Houseknecht 1979; Kurdek 1998; Leonard & Roberts 1998; McLanahan & Adams 1989; Menaghan 1983; Nock 1979; Renne 1970). Many scholars have suggested that the departure of older children from the parental nest tends to increase marital happiness - a finding demonstrated in several short-term longitudinal studies (Menaghan 1983; White & Edwards 1990). The results in Tables 3-5 suggest that a reduction in the rate of decline in marital happiness may indeed occur when older children leave the parental nest. This improvement could be due to a reduction in parenting responsibilities, an increase in privacy, or more opportunities for shared leisure activities between spouses. Nevertheless, family life cycle stages do not account for the overall pattern of change in marital happiness, because an independent effect of marital duration remains when changes associated with the family life cycle are controlled. More important, our results suggest that any improvements in marital happiness associated with departures of children from the home (as suggested by the family role and structure perspective) are temporary at best and that they slow down, rather than halt, the general decline in happiness.

The relatively rapid decline in marital happiness during the early years of marriage, shown in Figures 2 and 3, is consistent with social-psychological perspectives emphasizing the process of relationship disenchantment. The first years of marriage are difficult for many couples, as they negotiate the responsibilities of married life and learn to deal with the conflict that inevitably accompanies long- term relationships. Furthermore, individuals with high (and perhaps unrealistic) expectations about their partners and about marriage in general are likely to experience disappointment as they encounter the realities of married life (Booth 1999; Glenn 1996; Huston & Houts 1998). Pineo's (1961) notion that married partners gradually become less compatible over time, due to random changes in personal characteristics, also is relevant. According to exchange theory, marital relationships are based on the valued characteristics that each partner brings to the marriage. If these characteristics change over time, then equity in the exchange relationship is disrupted, resulting in a dedine in marital happiness. Finally, simple habituation to the partner also may contribute to the disenchantment process.

Although social-psychological and individualistic perspectives can account for declines in happiness during the early years of marriage, they are less successful in explaining declines during the later years of marriage. It seems unlikely that processes such as disillusionment or habituation continue for periods ranging up to fifty years. It is probable that random changes in personal characteristics (as described by Pineo 1961) continue throughout the life course. But after a time, changes in personal characteristics would not necessarily make couples less compatible. Indeed, changes in attitudes and interests in later life might result in couples growing closer together, for example, when couples discover new leisure activities that are mutually enjoyable. Although it is possible that intrinsic interactional processes account for declines in marital happiness over extremely

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Marital Happiness and Marital Duration / 1335

long time periods, most researchers working from social-psychological perspectives have not extended their predictions beyond the early years of marriage.

It is possible that some of the long-term decline in marital happiness observed in our study was due to a period effect. This effect appeared to take the form of a decline during the 1980s which leveled off during the 1990s. A number of changes in U.S. society have made marriage a more difficult arrangement since 1980, including growing economic inequality, increased work-family conflict associated with the movement of wives into the paid labor force, widespread disagreements about appropriate gender roles within marriage, and the rise of more individualistic attitudes toward marriage and family life. Indeed, some supporting evidence suggests that marital quality declined in recent decades. Glenn (1991), using merged data from the General Social Survey, reported a gradual decline from 1973 to 1988 in the percentage of people who reported that their marriages were "very happy-" Similarly, Rogers and Amato (1997) compared marriages in two generations of respondents. Although identical in terms of age at the time of data collection and duration of marriage, members of the more recent cohort reported less marital interaction, more marital conflict, and more problems in their marriages. Given these findings, it is possible that the decline in marital happiness in our data is due to a mixture of developmental processes intrinsic to marriage and shifts in the larger social structure and culture that introduced new sources of stress into marriages during the 1980s.

Regardless of the explanation for the long-term decline in marital happiness, our results demonstrate that the U-shaped pattern observed in most cross-sectional studies is artifactual. The U-shaped association apparent in cross-sectional data could be due to the gradual departure from the married population of unhappy couples through divorce, resulting in an "increase" in mean happiness among couples in long-term marriages. But this explanation is unlikely, given that most divorces occur early in marriage and the observed rise in happiness does not appear until after twenty years of married life. We believe that the cohort explanation advanced by Glenn (1998) is a more likely contender. Glenn's analysis specifically ruled out the possibility that attrition through divorce resulted in compositional differences across cohorts. Instead, his analysis suggested that the apparent U-shaped association between marital duration and marital happiness is due to older marriage cohorts experiencing higher levels of marital happiness than younger marriage cohorts. These older cohorts - married at a time when people held more pragmatic views about marriage, support for marriage was stronger, and couples were more committed to the norm of lifelong marriage - may have strengths that allow them to maintain high levels of marital happiness over the long haul.

Turning to a different issue, readers may have concerns about the small R- squared values in our analysis. Table 3 indicates that marital duration accounts for only about 4% of the variance in marital happiness - a finding that some observers may view as statistically significant but substantively unimportant. A

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different perspective, however, is obtained if one considers the gap between the highest level of marital happiness (at the beginning of the marriage) and the lowest level of marital happiness (after fifty years of marriage). This gap represents more than four points on the marital happiness scale, or an effect size of over one standard deviation. By almost any standard, a difference of this magnitude can be defined as a large effect (Cohen 1988). Although happiness changes slowly, small changes add up to large differences across long periods of time.

In conclusion, our results cast serious doubt on the widely accepted U-shaped association between marital duration and marital happiness. Our study suggests that marital happiness does not increase in the later years of marriage. After an initial decline, marital happiness either continues to decline (Figure 2) or remains flat (Figure 4). This conclusion may seem pessimistic. But it is worth remembering that these patterns represent shifts in central tendency. Not all married individuals experience a pattern of continuous decline. A goal for future longitudinal research is to identify subgroups of individuals who experience different trajectories of marital happiness - such as a decline in happiness followed by an improvement, or continuous high levels of happiness - and the factors that distinguish these individuals from those who follow the dominant trajectory of decline.

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