Relationship Quality Dynamics of

I use data from the National Survey of Families and Households to examine the durationdependence of relationship quality for cohabitors and marrieds and to evaluate whether the presence of children or prior union experience account for or moderate the effect of duration. The present study demonstrates that despite their short length, the quality of cohabiting unions varies with time. Cohabitors experience declines in relationship interaction and happiness that are similar to those experienced by marrieds. But unlike marriages, the stability of cohabiting unions is related to duration. This unique effect is indicative of the meaning of cohabitation as well as its role in the family life course. The higher levels of instability characterizing long cohabitations probably result from unrealized marital intentions. Most cohabitors expect to marry their partners and, provided that they do so within a few years of initiating the cohabiting union, perceived instability remains low. Without a commitment to marriage, the union is likely to fail. Thus, these analyses suggest that cohabitations serving as a prelude to marriage are characterized by low levels of instability, whereas cohabitations that are not readily transformed into marriages are hindered not only by high levels of instability but also especially low levels of relationship interaction and happiness. 1 Relationship Quality Dynamics of Cohabiting Unions Cohabitation is now a common feature in the life course. In 1970, there were 500,000 cohabiting couples, whereas today, more than 4.2 million couples cohabit (U.S. Bureau of the Census, 1999). A majority of marriages today are preceded by cohabitation (Bumpass & Sweet, 1989). Most of the decline in the first marriage rate and all of the decline in the remarriage rate are offset by corresponding increases in cohabitation (Bumpass, Sweet, & Cherlin, 1991). The rapid increase in cohabitation has led researchers to explore its linkages to other important life events, such as divorce (Bennett, Blanc, & Bloom, 1988; Booth & Johnson, 1988; DeMaris & MacDonald, 1993; DeMaris & Rao, 1992; Lillard, Brien, & Waite, 1995; Schoen, 1992) and nonmarital childbearing (Bachrach, 1987; Landale & Fennelly, 1992; Loomis & Landale, 1994; Manning, 1993, 1995; Manning & Landale, 1996). Essentially, researchers have treated cohabitation as a measure of a premarital event that may influence the likelihood of subsequent events. But is this how cohabitation ought to be conceptualized? Researchers continue to debate the answer to this question. Cohabiting unions are typically so short (averaging less than 2 years in duration) that we often think of them as transitory in nature. Indeed, research indicates that for most groups, cohabitation serves largely as a stepping stone to marriage (e.g., Manning, 1993, 1995). For some segments of the population though, cohabitation appears to be a longterm substitute for marriage (e.g., Puerto Rican women [Landale & Fennelly, 1992]). Some researchers argue that cohabitation is similar to singlehood (Rindfuss & VandenHeuvel, 1990), whereas others maintain that cohabitation is very much like marriage (Brown & Booth, 1996) and ought to be treated as a family status (Bumpass et al., 1991). To resolve this debate, we need to move beyond research whose interest in cohabitation 2 lies solely in its relationship to other life events (e.g., childbearing and divorce) and begin to explore the nature of the cohabiting relationship itself. In fact, understanding the nature of cohabiting relationships will help us to decipher those links between cohabitation and other important life events. The present analysis contributes to the debate concerning the meaning of cohabitation and also aims to enhance our knowledge of the nature of cohabitation. Using data from the National Survey of Families and Households, I compare the dynamics of cohabitors' and marrieds' relationship quality. Although some researchers (e.g., Brown & Booth, 1996; Nock, 1995) have investigated the quality of cohabiting unions, none to date has examined how the relationship quality of cohabitors varies by length of union, nor has anyone considered whether the association between relationship quality and relationship duration among cohabitors is similar to that observed for marrieds. Following a discussion of what we know about the relationship quality of cohabitors, I review research on marital quality and marital duration to formulate and test expectations concerning relationship quality and union duration among cohabitors. Relationship Quality among Cohabitors Cross-sectional studies demonstrate that, on average, cohabitors are involved in unions that are of poorer quality than marriages (Brown & Booth, 1996; Nock, 1995). Cohabitors report more frequent disagreements, less fairness and happiness, and greater instability than their married counterparts. However, a comparison of marrieds and cohabitors who plan to marry their partner (75 percent of cohabitors plan to formalize their union) reveals that the relationship quality of the two groups does not differ. Cohabitors without plans to marry their partner have especially poor relationship quality and are also in unions of longer duration than their counterparts with 3 marriage plans, suggesting that duration and relationship quality are negatively related. Indeed, relationship duration has a greater negative effect on the relationship quality of cohabitors than of marrieds (Brown & Booth, 1996). Marriage improves some aspects of cohabitors' relationship quality. For instance, cohabitors are less likely to use violence to solve relationship disputes after they marry (Brown, 1996). Marriage also increases cohabiting women's happiness with their relationship. And, marriage seems to ameliorate the negative consequences long unions have on perceptions of relationship fairness and happiness. Nevertheless, the strongest predictor of relationship quality at a later point in time is relationship quality at an earlier point in time; cohabitors' relationship quality appears stable. Marital Quality Over the Life Course Research on the association between marital quality and marital duration traditionally has been framed in terms of life cycle stages (see Adelmann, Chadwick, and Baerger [1996] for a review). As couples experience various life cycle stages (e.g., the birth of a child, nestleaving, or retirement), marital quality changes in a U-shaped manner. Although family life cycle stage is a useful concept, it is not an ideal empirical tool. Nock (1979) demonstrates that simply measuring the presence or absence of children as well as the length of marriage is sufficient to capture the dynamics of marital quality. Further, critics (e.g., Adelmann et al., 1996; Glenn, 1989; Nock, 1979) note that the life cycle stage framework has limited applicability. For instance, how can we account for declines in the marital quality of nonparents (cf. White & Booth, 1985)? Recent research has approached marital quality dynamics from a life course perspective. Unlike the family life cycle approach, which restricts its focus to predetermined family stages, 4 the life course perspective allows for variation across families in the experience, timing, and sequencing of events. One study (Adelmann et al., 1996) using a life course approach indicates that positive dimensions of marital quality exhibit a curvilinear, U-shaped trend, whereas negative dimensions of marital quality decline linearly across time. These patterns hold for both blacks and whites, although blacks consistently report lower levels of positive marital quality and higher levels of negative marital quality. The presence of children accounts for the curvilinearity in some dimensions of positive marital quality, but does not appear to alter the relationship between negative marital quality and duration. The authors offer three possible life course explanations for these trends. Marital quality may improve over time due to increased familiarity with one's spouse. Alternatively, marital quality could increase over time through selection out of marriage by those whose marital quality is low. Finally, the trends could reflect a cohort effect in which younger cohorts are less positive about their marriages than older cohorts. Rogers and Amato's (1997) comparison of two distinct marriage cohorts reveals that some dimensions of marital quality, including interaction and conflict, have declined across cohorts, although other dimensions, such as happiness and instability, remain unaffected by cohort membership. Glenn's (1989) examination of repeated cross-sectional data from the General Social Survey yields somewhat different findings. While his analyses reveal minimal effects of children on marital happiness, they also indicate that the effect of duration on happiness became increasingly negative between 1973 and 1987. He argues that this negative effect is conservative since divorce would have selected out an increasing share of unhappy marriages as marriage cohorts age. More recent research by Glenn (1998) resolves much of the discrepancies in the literature 5 on this topic. Using data from the General Social Survey, Glenn compares the marital quality of five unique ten-year marriage cohorts. He constructs a marital success index, a dichotomous measure in which success means the respondent reports s/he is "very happy" with the first marriage. The absence of success is indicated either by the respondent's report that s/he is less than "very happy" with the first marriage or that the first marriage dissolved through separation or divorce. This strategy avoids the bias inherent in those studies ignoring the sample selection effect due to divorce and separation. Pooling the five marriage cohorts, Glenn replicates the cross-sectional finding that marital quality is a U-shaped curve. However, cohort analyses reveal that all five marriage cohorts experience linear declines in marital quality over time and that older cohorts have higher marital quality, on average. Additional analyses suggest that marital quality declines markedly over the first decade, then declines at a somewhat slower pace for the next two decades, and finally decreases at a very slow rate through the fifth decade. Glenn concludes that the upturn in marital quality observed for late-term marriages is primarily a function of cohort differences in marital success. In one of the few longitudinal analyses of marital quality, Johnson, Amoloza, and Booth (1992) conclude that marital quality is remarkably stable over time. Positive dimensions of marital quality, including happiness and interaction, decline over time, whereas negative dimensions of marital quality, such as divorce proneness, marital problems, and disagreement, do not appear to change significantly. Further, the stability of marital quality does not depend on marital duration; "newer" marriages exhibit stability comparable to "older" marriages. In fact, even among couples who eventually divorce, marital quality is stable. The stability of marital quality is primarily a function of the relationship environment (Johnson & Booth, 1998). Taken together, studies of cohabitors' relationship quality and the literature on marital 6 quality suggest potential similarities in union quality patterns for the two groups. For both marrieds and cohabitors, duration is negatively associated with relationship quality, yet relationship quality remains stable over time (Brown & Booth, 1996; Johnson et al., 1992). Consequently, I expect relationship duration to have similar effects on the relationship quality of both cohabitors and marrieds. In the present analysis, I evaluate whether the dynamics of cohabitors' relationship quality exhibits a pattern analogous to that found for marital quality. Analysis Strategy Researchers have determined that there are two conceptually distinct dimensions of marital quality: a positive dimension comprised of factors such as happiness and interaction, and a negative dimension, including marital disagreements and instability (Johnson et al., 1986). These two dimensions exhibit unique patterns across marital duration (Adelmann et al., 1996; Johnson et al., 1992). In this paper, I consider both positive and negative dimensions of cohabitors' and marrieds' relationship quality. I begin by examining the direct effect of union duration on relationship quality by regressing relationship quality on union duration. Subsequent analyses test various explanations for the effect of duration on the relationship quality of cohabitors, specifically, the presence of children and prior union history. While some researchers find that children mediate the effect of marital duration on certain dimensions of marital quality (e.g., Adelmann et al., 1996; Glenn, 1989), others find that marital quality declines over time regardless of whether children are present (e.g., White & Booth, 1985). Prior union experience is associated with poorer relationship quality (Brown & Booth, 1996) and could influence the effect of duration on the quality of cohabiting unions. Ever-married cohabitors are, on average, older, more likely to have children, less likely to report plans to marry, and involved in unions of longer durations 7 (Bumpass & Sweet, 1989). The independent effects of children and prior union experience as well as their interactive effects with duration on relationship quality are tested. Finally, I consider the role of plans to marry among cohabitors to determine whether effects of duration on the relationship quality of cohabitors planning to marry is especially similar to that for marrieds. A Note About Selection Effects Although the relationship quality of most cohabitors does not significantly differ from that of marrieds at a given point in time (Brown & Booth, 1996), cohabitation is a selective process (cf. Booth & Johnson, 1988; Lillard et al., 1995). Not only are persons with low relationship quality likely to dissolve their unions but also persons with high relationship quality and plans to marry are likely to exit cohabitation through marriage. It is impossible to correct for these selectivity biases given the data at hand and, indeed, similar biases are evident in most analyses of the effects of marital duration on marital quality. Since about 55 percent of cohabitations are formalized through marriage while the remaining 45 percent dissolve (Bumpass & Lu, 2000), it is possible that most of the selection effect is "canceled out" by these opposing biases. Data and Measures Data come from the first wave of the National Survey of Families and Households (NSFH. The NSFH is a multistage probability sample of 13,007 persons who were interviewed in 1987-88. These data are arguably the best available for studying the cohabiting population since cohabitors were oversampled (N=678) and extensive information was gathered about the quality of their unions. Over 6,800 respondents were married at first interview. Fewer than 5 percent of cohabiting unions last more than 10 years (Bumpass & Sweet, 1989). To maximize comparability with marriages, I restrict the analyses to those respondents in cohabiting or marital unions of no more than 10 year's duration. This strategy has been employed in other research on 8 NSFH cohabitors (Brown, 2000; DeMaris & MacDonald, 1993; Nock, 1995; Thomson & Colella, 1992). Also, only blacks and whites are examined here due to the small numbers of Hispanic, Asian, and other race cohabitors. These restrictions result in 646 cohabitors and 3,086 marrieds for analysis. Dependent Variables Three measures of relationship quality are examined (Table 1 shows the means and standard deviations for all variables used in the analyses). Relationship happiness refers to the respondent's response to the question, "Taking all things together, how happy are you with your relationship?" Responses range from very unhappy (=1) to very happy (=7). Relationship interaction, a six-category variable, measures the amount of time the respondent spent alone with the partner in the past month. Although happiness and interaction are both positive dimensions of relationship quality, the two measures do not hold together as a factor particularly well (alpha= 0.53) and hence they are analyzed separately. Finally, relationship instability gauges the respondent's estimation (on a five-point scale) of the chance that the relationship will dissolve. Independent Variables Relationship duration is measured in months in the NSFH, but for ease of interpretation, I have multiplied this measure by 12 to yield a measure in which the unit is one year. The presence of children in the household, prior marital experience, and prior cohabiting experience are all indicator variables. Plans to marry among cohabitors is also a dichotomous measure, coded 1 if the respondent reports that s/he has definite plans or thinks eventually s/he will marry the current cohabiting partner, and 0 otherwise. Control Variables Variables associated with cohabitation and relationship quality are included as control variables. 9 A control for race is included in all models since prior research (e.g., Adelmann et al., 1996) demonstrates that blacks report poorer marital quality than whites and there are considerable racial differences in union formation rates (Raley, 1996). Gender, coded 1 for female, is included as a control variable since women and men typically report unique views of marital quality (Thompson & Walker, 1989) and cohabitation is more common among women (Bumpass & Sweet, 1989; Thornton, 1988). Both education and age are associated with cohabitation and relationship quality (Brown & Booth, 1996; Bumpass & Sweet, 1989; Glenn, 1990; Nock, 1995) and thus are included as controls. Education measures the number of years of school completed. Age is coded in years. Model Estimation The dynamics of black and white cohabitors' and marrieds' relationship quality are analyzed using ordinary least squares regression. All analyses are weighted using the NSFH individuallevel weight to adjust for oversampling. Results Table 1, which shows the means and standard deviations of all variables used in the analyses, reveals that although cohabitors report significantly more interaction with their partners than do marrieds, cohabitors also are significantly less happy with their relationships and believe their relationships are more unstable than do their married counterparts. The average duration of a cohabiting relationship is just under 3 years, whereas among marrieds, average marital duration is slightly over 5 years. Marrieds are significantly more likely to have children than are cohabitors (66 versus 41 percent, respectively). Although cohabitors are more likely to have prior marital experience, they are less likely to have prior cohabiting experience than marrieds. And, as expected, about 72 percent of cohabitors report plans to marry their current partners. 10 Multivariate analyses, shown in Table 2, yield similar findings. Cohabitors report significantly more interaction with their partner, but less relationship happiness and more relationship instability than do marrieds, confirming earlier work (Brown & Booth, 1996) that compares relationship quality across union type. Further, union type modifies the effect of duration on relationship happiness and instability (see Model B in Table 2). Duration has a similar negative impact on relationship interaction for cohabitors and marrieds; the interaction between duration and union type is not significant. However, duration has an especially harsh negative effect on cohabitors' happiness with their relationship. And, duration is positively related to instability among cohabitors whereas among marrieds, the association is not significant. For cohabitors in long unions, instability is particularly high. Due to the differential effects of duration on the relationship quality of cohabitors and marrieds, I present separate models by union type. This strategy facilitates comparisons between cohabiting and marital unions and at the same time preserves the focus on cohabitors. Cohabitors' happiness with their relationships, patterns of interaction, and perceived instability are all duration-dependent, as shown in Table 3. Figure 1 graphically depicts these regression results (all other covariates are coded at the mean). Over time, happiness and interaction decrease while instability increases. Similar to Glenn's (1998) analysis of marital quality, these results demonstrate that cohabitors also experience a linear decline in relationship quality over the first decade. Supplemental analyses (not shown) confirm that these relationships are truly linear; quadratic terms are neither significant nor improve the fit of the models. The effects of marital duration on the quality of marriages are shown in Table 3. These regression results are graphed in Figure 2. The pattern of interaction across duration is essentially the same for cohabitors and marrieds. Average levels of happiness appear slightly 11 higher among marrieds than cohabitors, but happiness declines linearly over time for both groups. Instability exhibits unique patterns for marrieds and cohabitors. While cohabitors experience a steady increase in relationship instability over time, marrieds' levels of instability are not related to duration. Rather, marital instability appears static across the first decade of marriage. These findings support Johnson et al.'s (1992) assertion that positive dimensions of marital quality tend to decline with time while negative dimensions, such as instability, remain stable. Among marrieds, race is significantly associated with marital interaction, happiness, and instability. Blacks report lower levels of interaction and happiness and higher levels of instability than whites, confirming findings from recent research (Adelmann et al., 1996) on racial differences in marital quality. Note that there are no significant racial differences in relationship quality among cohabitors. Children The presence of children tends to worsen cohabitors' relationship quality, but does not explain the negative association between duration and relationship quality (as shown in Table 4). Children decrease interaction and relationship happiness among cohabitors, but do not alter perceptions of the stability of the relationship. Similar effects are observed for marrieds. Additional analyses (results not shown) reveal that differentiating stepchildren from biological children does not alter the pattern of effects. Also, the presence of adult children (i.e., children who are at least 18 years of age) has no significant effects on the three dimensions of relationship quality. Among cohabitors, children and duration negatively interact in their effects on relationship interaction and happiness (results not shown). In long cohabiting unions, children are associated with especially low levels of interaction and happiness, perhaps because nearly half of these unions involve children from prior unions. Among marrieds, children do not 12 modify the effect of duration on marital quality. Children have similar effects on relationship happiness and instability for both cohabitors and marrieds, but the negative effect of children on interaction is somewhat weaker for cohabitors than marrieds (result not shown). Prior Union Experience Prior union experience has significant consequences for the relationship quality of cohabitors and marrieds, but these effects are independent of duration, as shown in Table 5. Among cohabitors, prior cohabitation experience decreases partner interaction and happiness with the current relationship and increases perceived instability. Among marrieds, prior cohabitation experience decreases relationship interaction and happiness and increases instability. There are no significant effects of prior marital unions. Union type does not modify the effects of prior cohabitation experience on relationship quality, nor does duration (results not shown), meaning that the adverse effects of earlier cohabiting unions persist throughout the duration of the current union. Plans to Marry It is difficult to determine the causal order between cohabitors' plans to marry and relationship quality since both are measured at the same point in time. Indeed, some cohabitors likely enter cohabitation because they plan to marry, while others enter cohabitation to evaluate whether their partner is compatible for marriage. Hence, treating plans to marry as a predictor of relationship quality is perhaps ambiguous, but see Brown and Booth (1996) for evidence that plans to marry and relationship quality are distinct constructs. As shown in Table 6, cohabitors with plans to marry their partner report higher relationship quality, on average, than those without such plans. The inclusion of an indicator for plans to marry weakens the duration coefficient for cohabitors' reports of relationship interaction 13 and happiness by 7 and 24 percent, respectively. Further, plans to marry accounts for the positive effect of duration on relationship instability (although this is not surprising given the high correlation between the two--approximately 0.40). Plans to marry modifies the effect of duration on instability such that among those in unions of relatively short duration, plans to marry is associated with lower levels of relationship instability, while among those in relatively long unions, plans to marry is actually associated with higher levels of instability (result not shown). This finding implies that cohabitors with marriage plans expect that their unions will be transformed quickly into marriages. When these expectations are not met, cohabitors perceive greater instability. In contrast, couples who do not desire marriage gain confidence over time that their relationship will remain intact. Hence, the effect of duration on relationship instability is conditioned by the cohabitor's marital intentions. Explaining the Duration-Dependence of Relationship Quality To minimize the ambiguity associated with the causal order issue, the final model differentiates among cohabitors with and without plans to marry and marrieds. The results shown in Table 7 demonstrate that the effect of duration on relationship quality is similar for cohabitors planning to marry and marrieds. For cohabitors without marriage plans, duration apparently has no significant effects on the quality of the relationship. Cohabitors with plans to marry and marrieds report less interaction with their partners and less happiness with their relationships over time. Cohabitors with plans to marry also report greater instability at higher levels of duration, probably because their unfulfilled union intentions generate uncertainty. The declines in relationship interaction (z = -0.34, n.s.) and happiness (z = -1.41, n.s.) experienced by cohabitors with plans to marry and marrieds do not significantly differ. In contrast, although duration is positively associated with relationship instability among cohabitors with marriage 14 plans, duration has no significant effect on relationship instability among marrieds. These two coefficients are significantly different (z = 2.34, p < 0.05) (see Clogg, Petkova, & Haritou, 1995 for a discussion of tests of coefficient differences across models). Cohabitors without marriage plans experience little duration-related changes in their relationship quality. Most cohabitors (approximately 65 percent) without marriage plans have been married before (Brown & Booth, 1996). Their lack of plans to marry suggest a hesitancy to reenter marriage. In fact, previously married cohabitors without plans to marry perhaps are happier with their relationships and report lower levels of relationship instability than their never-married counterparts (although due to the small sample size, these coefficients do not achieve statistical significance), supporting the notion that many divorcees prefer cohabitation over remarriage. Discussion Cohabiting unions are experienced by a majority of young people today (Bumpass & Sweet, 1989). While researchers (e.g., Brown & Booth, 1996; Nock, 1995) have compared the relationship quality of cohabitors and marrieds, little attention has been paid to the dynamics of cohabitors' relationship quality. Does the quality of cohabiting unions vary according to union duration? If so, how similar is the pattern for cohabiting unions to that observed for marriages? In the present study, I examined the duration-dependence of relationship quality for cohabitors and marrieds and evaluated whether the presence of children or prior union experience account for or moderate the effect of duration. Cohabitors and marrieds experience similar declines in interaction with their partner during the first decade of their union. Both groups also experience lower levels of happiness across time, although happiness is consistently higher among marrieds than cohabitors. Relationship instability increases considerably over time among cohabitors, but remains stable among marrieds. For cohabitors, long union duration 15 has particularly devastating consequences for levels of happiness and instability. Both the presence of children and prior cohabitation experience are significantly associated with lower levels of relationship quality. The effect of duration on cohabitors' relationship quality is modified by the presence of children. Cohabitors in long unions with children report especially low levels of relationship interaction and happiness, possibly because nearly one-half of such unions involve children from previous cohabitations or marriages. There are important differences among cohabitors in the effects of duration on relationship quality. Among cohabitors without marriage plans, duration has no significant effects on the three dimensions of relationship quality. Among cohabitors with plans to marry, the effects of duration are similar to those observed for marrieds. For both groups, longer unions are associated with poorer relationship quality (except marrieds experience no significant duration-related changes in instability). Cohabiting unions are of relatively short duration, yet the dynamics of relationship quality parallel that of marriages in many regards. An important difference in the durationrelationship quality association for cohabitations and marriages is that the instability of cohabiting unions increases over time, whereas among marriages, reported instability does not vary with duration. This difference is probably due to the role of cohabitation in the life course. For most cohabitors, cohabitation is a transitory stage, typically a step in the courtship process. Most people enter cohabitation not expecting a long-term union but rather a short-term substitute for marriage. Not surprisingly, half of all cohabiting unions are formalized through marriage or dissolve within two years, and over 90 percent end within 5 years (Bumpass & Sweet, 1989). Hence, the longer a cohabiting union persists, the greater the perceived instability since cohabiting unions that are not formalized through marriage are likely to soon end in separation. 16 Fewer than 10 percent of cohabiting unions are maintained for an extended (i.e., 5 or more years) period of time. The present study demonstrates that despite their short length, the quality of cohabiting unions varies with time. Cohabitors experience declines in relationship interaction and happiness that are similar to those experienced by marrieds. But unlike marriages, the stability of cohabiting unions is related to duration. This unique effect is indicative of the meaning of cohabitation as well as its role in the family life course. The higher levels of instability characterizing long cohabitations probably results from unrealized marital intentions. Most cohabitors expect to marry their partners and, provided that they do so within a few years of initiating the cohabiting union, perceived instability remains low. Instability levels are extremely high for cohabitors in relatively long unions who intend to marry their partner. The longer cohabitors' intentions remain unmet, the less confident they are that the relationship will remain intact. Factors hindering marriage entry may include relationship stressors such as children or prior union experience, but ultimately, at least one partner is hesitant to marry. Without a commitment to marriage, the union is likely to fail. 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Journal ofFamily Issues, 6, 435-49. 20Table 1. Weighted Means (standard deviations) of Variables used in the Analyses*