The growing economic resemblance of spouses has contributed to rising inequality by increasing the number of couples in which there are two high- or two low-earning partners. The dominant explanation for this trend is increased assortative mating. Previous research has primarily relied on cross-sectional data and thus has been unable to disentangle changes in assortative mating from changes in the division of spouses’ paid labor—a potentially key mechanism given the dramatic rise in wives’ labor supply. We use data from the Panel Study of Income Dynamics (PSID) to decompose the increase in the correlation between spouses’ earnings and its contribution to inequality between 1970 and 2013 into parts due to (a) changes in assortative mating, and (b) changes in the division of paid labor. Contrary to what has often been assumed, the rise of economic homogamy and its contribution to inequality is largely attributable to changes in the division of paid labor rather than changes in sorting on earnings or earnings potential. Our findings indicate that the rise of economic homogamy cannot be explained by hypotheses centered on meeting and matching opportunities, and they show where in this process inequality is generated and where it is not.
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We do not use the 1950 census because only one person in the household was asked about their earnings, and thus spouses’ earnings correlations cannot be calculated.
Defining sorting as the association between spouses’ FTFY earnings potential as predicted by characteristics in a given year assumes perfect foresight of changes that affect future earnings, such as changes in occupation or educational attainment. To the extent that individuals do not foresee these changes, we will overestimate the contribution of sorting on earnings potential. Sensitivity tests show that estimating predicted earnings based only on characteristics at the time of marriage yields results very similar to those presented here.
Because the correlation between spouses’ earnings has been stable since approximately 1990 but inequality has risen, estimates of the contribution of economic homogamy to inequality are larger in earlier periods.
Supplementary analyses suggest that the correlation between spouses’ earnings potential did not increase because the correlation between spouses’ years of schooling declined over this period in the PSID. The declining correlation between spouses’ years of schooling is inconsistent with many assortative mating studies, which have reported an increase in educational homogamy (see Schwartz 2013 for a review). However, the correlation coefficient is affected by changes in the marginal distributions of spouses’ education. Log-linear models controlling for shifts in the marginal distributions of education using the PSID produce increases in educational homogamy similar to those estimated by Schwartz and Mare (2005). It is debatable whether the best way to measure the effects of educational assortative mating on earnings homogamy and inequality is to control for the marginal distributions (Breen and Salazar 2011). However, resolving this issue is beyond the scope of this article.
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This research was carried out using the facilities of the Center for Demography and Ecology at the University of Wisconsin–Madison (R24 HD047873) and was prepared for presentation at the 2014 annual meeting of the Population Association of America in Boston. An earlier version of this article was presented at the 2013 International Sociological Association Research Committee on Social Stratification and Mobility (RC28) in Trento, Italy. We are grateful to Russell Dimond, Greg Duncan, Christopher McKelvey, Robert Pollak, and the participants of seminars and lectures at Duke University; New York University; University of California, Los Angeles; Washington University; and University of Wisconsin–Madison for helpful comments and advice.
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Gonalons-Pons, P., Schwartz, C.R. Trends in Economic Homogamy: Changes in Assortative Mating or the Division of Labor in Marriage?. Demography 54, 985–1005 (2017). https://doi.org/10.1007/s13524-017-0576-0
- Economic homogamy
- Assortative mating
- Division of paid labor
- Life course