Professor Sonia Oreffice

Using the American Community Survey data 2012-2013, I study married and cohabiting same-sex couples. I show that gay couples exhibit more specialization and less similarity than lesbian couples, while marriage makes gay and lesbian couples more alike than cohabiting couples, in terms of larger earnings differences for lesbians, and more positive sorting by education for gays. Education does not increase the odds of marriage among same-sex couples, contrary to heterosexual couples; lesbians are instead similar to heterosexual couples in their education being negatively associated to the number of children.

This study investigates how spouses' cultural backgrounds mediate the role of intra-household bargaining in the labor supply decisions of foreign-born and US-born couples, in a collective-household framework. Using data from the 2000 US Census, I show that the hours worked by US-born couples, and by those foreign-born coming from countries with gender roles similar to the US, are significantly related to common bargaining power forces such as differences between spouses in age and non-labor income, controlling for both spouses' demographic and socioeconomic characteristics. Households whose culture of origin supports strict and unequal gender roles do not exhibit any association of these power factors with their labor supply decisions. This cultural asymmetry suggests that spousal attributes are assessed differently across couples within the US, and that how spouses make use of their outside opportunities and economic and institutional environment may depend on their ethnicities. © 2014 Springer Science+Business Media New York.

Many international treaties come into force only after a minimum number of countries have signed and ratified the treaty. Minimum participation constraints are particularly frequent in the case of environmental treaties dealing with global commons, where free-riding incentives are strong. Why do countries that know they have an incentive to free-ride accept to "tie their hands" through the introduction of a minimum participation constraint? This article addresses the above issues by modeling the formation of an international treaty as a three-stage non-cooperative coalition formation game. Both the equilibrium minimum participation constraint and the number of signatories-the coalition size-are determined. This article, by showing that a non-trivial partial coalition, sustained by a binding minimum participation constraint, forms at the equilibrium, explains the occurrence of minimum participation clauses in most international environmental agreements. It also analyses the endogenous equilibrium size of the minimum participation constraint. © 2009 Springer Science+Business Media B.V.

We analyze, from a theoretical perspective, the impact of innovations in birth control technology on intrahousehold allocation of resources. We consider a model of frictionless matching on the marriage market in which men, as well as women, differ in their preferences for children; moreover, men, unlike women, must many to enjoy fatherhood. We show that more efficient birth control technologies generally increase the "power," hence the welfare, of all women, including those who do not use them. This "empowerment" effect requires that the new technology be available to single women. An innovation reserved to married women may result in a "disempowerment" effect. © 2008 by The University of Chicago. All rights reserved.

We investigate the impact of sex ratios by education and metropolitan area on spouses' bargaining power and labor supplies, to capture the local and qualitative nature of mate availability. Using Current Population Survey and Census data for 2000, 1990, and 1980, we estimate these effects in a collective household framework. We find that a higher relative shortage of comparably educated women in the couple's metropolitan area reduces wives' labor supply and increases their husbands'. The impact is stronger for couples in higher education groups but not significant for high school graduates. Results are similar across decades. No such effects are found for unmarried individuals. (JEL D1, J22). © 2008 Western Economic Association International.

We develop a frictionless matching model under transferable utility where individuals are characterized by a continuous trait and a binary attribute. The model incorporates attributes for which there are heterogeneous preferences in the population regarding their desirability, that is, the impact of the traits cannot be summarized by a one-dimensional attractiveness index. We present a general resolution strategy based on optimal control theory, and characterize the stable matching. We then consider education and smoking status, further specify the model by observing that there are more male than female smokers above each education level, and derive additional predictions about equilibrium matching patterns and how individuals with different smoking habits marry down or marry up by education. Using the CPS March and Tobacco Use Supplements for the period 1996 to 2003, we find that the hypotheses based on our model predictions are borne out in the data.

We develop a bidimensional matching model under transferable utility, where individuals are characterized by a continuous trait (e.g., socioeconomic status) and a binary attribute (e.g., smoking status).  The model is "truly multidimensional", in the sense that the impact of the traits cannot be summarized by a one-dimensional index.  We present a general resolution strategy based on optimal control theory, and characterize the stable matching.  We derive testable predictions about equilibrium matching patterns.  Using US data, we find that the observed marital sorting of smokers and non-smokers by education is consistent with our model.

I estimate the impact of abortion legalization on spouses' labor supplies to test whether legalization increased women's household bargaining power, in a collective household behavior framework. Based on CPS data, I find that wives' labor supply decreased and their husbands' increased, which is consistent with the bargaining hypothesis. This contrasts with most studies of abortion and birth control technologies, which predict a labor supply effect only for women, and of opposite sign. Also consistent with the bargaining interpretation, I estimate no significant impact on anti-abortion religious couples or on those who regularly used contraceptives. PSID data yield supportive evidence. © Springer Science+Business Media, LLC 2007.

This study estimates the effect of intra-household-bargaining on gay and lesbian couples' labor supplies, in order to determine how homosexual and heterosexual decision making compare, in a collective-household framework. Data from the 2000 US Census show that couples of all types exhibit a significant response to bargaining power shifts, as measured by age and non-labor-income differences between partners. Among gay, lesbian, and heterosexual cohabiting couples, a relatively young or rich partner has more bargaining power and supplies less labor, the opposite being true for his/her mate. Among married couples, the older spouse is instead more powerful, or the richer. No such patterns are found among same-sex roommates. © 2010 Elsevier B.V.

We analyze the marriage-market aspects of weight and height in the United States using data from the Panel Study of Income Dynamics on anthropometric characteristics of both spouses. We find evidence of positive sorting in spouses' body mass index (BMI), weight, and height. Within couples, gender-asymmetric trade-offs arise not only between physical and socioeconomic attributes, but also between anthropometric attributes, with significant penalties for fatter women and shorter men. A wife's obesity (BMI or weight) measures are negatively correlated with her husband's income, education, and height, controlling for his weight and her height, along with spouses' demographic and socioeconomic characteristics. Conversely, heavier husbands are not penalized by matching with poorer or less educated wives, but only with shorter ones. Height is valued mainly for men, with shorter men matched with heavier and less educated wives.

Social scientists have overwhelmingly documented a strong and increasing educa-tional homogamy between spouses. When estimating sorting by education, the pres-ence of measurement error in the education variables or random factors in the matching process may underestimate the actual degree of assortative mating, simultaneity bias may overestimate it, while omitting other individual characteristics relevant in the marriage market may under- or overestimate it. We address these issues using an in-strumental variables approach based on exploiting genetic variation in polygenic scores and controlling for population strati?cation. Speci?cally, we instrument spousal edu-cation with his/her educational polygenic score while controlling for own educational polygenic score. If the exclusion restriction is satis?ed, our ?ndings indicate that (1) assortative mating is underestimated when using OLS, and that (2) male education is correlated with other matching-relevant socioeconomic characteristics, while female education is productive per se in the matching. If the exclusion restriction is not satis?ed, our evidence is consistent with (2). This suggests that individual socioeco-nomic attractiveness in the marriage market is multidimensional for men, but can be summarized with education for women.

We analyze how sexual orientation is related to household financial decisions using 2000 US Census data, and find that lesbian couples pay higher annual mortgages relative to house value than do heterosexual or gay couples. We also estimate that cohabiting heterosexuals pay more than their married counterparts. We link this homosexual-specific differential to homeowners' propensity to save. This differential reflects the gender composition of same-sex households, and their very low fertility, in addition to the precautionary motives increasing cohabiting couples' propensity to save relative to married ones. Evidence from retirement and social security income of older couples exhibits the same pattern of differentials by sexual orientation and cohabiting status. © 2011 Springer Science+Business Media, LLC.

We construct a marriage market model of matching along multiple dimensions, some of which are unobservable, in which individual preferences can be summarized by a one-dimensional index combining the various characteristics. We show that, under testable assumptions, these indices are ordinally identified and that the male and female trade-offs between their partners' characteristics are overidentified. Using PSID data onmarried couples, we recover the marginal rates of substitution between body mass index (BMI) and wages or education: men may compensate 1.3 additional units of BMI with a 1 percent increase in wages, whereas women may compensate two BMI units with 1 year of education. © 2012 by The University of Chicago. All rights reserved.

We analyze the interaction of black-white race with physical and socioeconomic characteristics in the US marriage market, using data from the Panel Study of Income Dynamics. We estimate who inter-racially marries whom along anthropometric and socioeconomic characteristics dimensions. The black women who inter-marry are the thinner and more educated in their group; instead, white women are the fatter and less educated; black or white men who inter-marry are poorer and thinner. While women in ìmixedî couples Önd a spouse who is poorer but thinner than if they intra-married, black men match with a white woman who is more educated than if they intra-married, and a white man Önds a thinner spouse in a black woman. Our general Öndings are consistent with the ìsocial status exchangeîhypothesis, but the Önding that black men who marry white women tend to be poorer than black men who marry black women is not.

We study the determinants of season of birth of the ?rst child, for White non-Hispanic married women aged 25-45 in the US, using birth certi?cate and Census data. The prevalence of good season (quarters 2 and 3) is signi?cantly related to mother?s age, education, and smoking status during pregnancy, as well as to receiving WIC food during pregnancy and to pre-pregnancy body mass index. Moreover, those who did not use assisted reproductive technology (ART) present a higher prevalence of good season births. The frequency of good season is also higher and more strongly related to mother?s age in states where cold weather is more severe, and varies with mother?s occupation, exhibiting a particularly strong positive association with work-ing in ?education, training, and library?. Remarkably, this relationship between good season and weather disappears for mothers in ?education, training, and library? oc-cupations, revealing that season of birth is a matter of choice and preferences, not simply a biological mechanism. We estimate the compensating wage di?erential for mothers who work in jobs other than ?education, training, and library?, which allows us to provide an upper-bound to the life-time value of good season of birth of about USD 1,000,000. Finally, we present evidence that good season of birth is positively related to health at birth conditional on several maternal characteristics.