Showing papers by "Yu Xie published in 2012"

Estimating Heterogeneous Treatment Effects with Observational Data

Abstract: Individuals differ not only in their background characteristics, but also in how they respond to a particular treatment, intervention, or stimulation. In particular, treatment effects may vary systematically by the propensity for treatment. In this paper, we discuss a practical approach to studying heterogeneous treatment effects as a function of the treatment propensity, under the same assumption commonly underlying regression analysis: ignorability. We describe one parametric method and two non-parametric methods for estimating interactions between treatment and the propensity for treatment. For the first method, we begin by estimating propensity scores for the probability of treatment given a set of observed covariates for each unit and construct balanced propensity score strata; we then estimate propensity score stratum-specific average treatment effects and evaluate a trend across them. For the second method, we match control units to treated units based on the propensity score and transform the data into treatment-control comparisons at the most elementary level at which such comparisons can be constructed; we then estimate treatment effects as a function of the propensity score by fitting a non-parametric model as a smoothing device. For the third method, we first estimate non-parametric regressions of the outcome variable as a function of the propensity score separately for treated units and for control units and then take the difference between the two non-parametric regressions. We illustrate the application of these methods with an empirical example of the effects of college attendance on womens fertility.

Is American Science in Decline

Abstract: Alarmists argue that the United States urgently needs more and better-trained scientists to compete with the rest of the world. Their critics counter that, far from facing a shortage, we are producing a glut of young scientists with poor employment prospects. Both camps have issued reports in recent years that predict the looming decline of American science. Drawing on their extensive analysis of national data sets, Yu Xie and Alexandra Killewald have welcome news to share: American science is in good health. "Is American Science in Decline?" does reveal areas of concern, namely scientists' low earnings, the increasing competition they face from Asia, and the declining number of doctorates who secure academic positions. But the authors argue that the values inherent in American culture make the country highly conducive to science for the foreseeable future. They do not see globalization as a threat but rather a potential benefit, since it promotes efficiency in science through knowledge-sharing. In an age when other countries are catching up, American science will inevitably become less dominant, even though it is not in decline relative to its own past. As technology continues to change the American economy, better-educated workers with a range of skills will be in demand. So as a matter of policy, the authors urge that science education not be detached from general education.

International Fertility Change: New Data and Insights from the Developmental Idealism Framework

Abstract: Many scholars have offered structural and ideational explanations for the fertility changes occurring around the world. This paper focuses on the influence of developmental idealism-a schema or set of beliefs endorsing development, fertility change, and causal connections between development and fertility. Developmental idealism is argued to be an important force affecting both population policy and the fertility behavior of ordinary people. We present new survey data from ordinary people in six countries-Argentina, China, Egypt, Iran, Nepal, and the United States-about the extent to which developmental idealism is known and believed. We ask individuals if they believe that fertility and development are correlated, that development is a causal force in changing fertility levels, and that fertility declines enhance the standard of living and intergenerational relations. We also ask people about their expectations concerning future trends in fertility in their countries and whether they approve or disapprove of the trends they expect. The data show widespread linkage in the minds of ordinary people between fertility and development. Large fractions of people in these six settings believe that fertility and development are correlated, that development reduces fertility, and that declines in fertility foster development. Many also expect and endorse future declines in fertility.

Modeling individual-level heterogeneity in racial residential segregation

Abstract: We investigate the dynamic relationship between residential choices of individuals and resulting long-term aggregate segregation patterns, allowing for feedback effects of macrolevel neighborhood conditions on residential choices We reinterpret past survey data on whites’ attitudes about desired neighborhoods as revealing large heterogeneity in whites’ tolerance of black neighbors Through agent-based modeling, we improve on a previous model of residential racial segregation by introducing individual-level heterogeneity in racial tolerance Our model predicts, in the long run, a lower level of residential racial segregation than would be true with homogeneous racial tolerance Further analysis shows that whites’ tolerance of black neighbors is closely associated with their overall racial attitudes toward blacks

Hard Skills, Soft Skills: The Relative Roles of Cognitive and Non-cognitive Skills in Intergenerational Social Mobility

Abstract: In this article, we adopt a two-step strategy to assess the relative roles of cognitive and noncognitive skills in mediating the relationship between family SES and children’s academic achievement using data from the Early Childhood Longitudinal Study-Kindergarten Cohort. First, we decompose the total effects of family background on children’s achievement into: (1) direct effects of family background, and (2) indirect effects via cognitive and non-cognitive skills. We estimate this model using skills alternatively measured at four points in time between kindergarten and the 5th grade. Second, we use growth curve and fixed effect models to study the changing relationship between family background and skill formation over time. Overall, we find that cognitive skills are stronger mediators of family SES than non-cognitive skills. This is both because non-cognitive skills are less predictive of later achievement and because they are less affected by family SES. However, the mediating role of non-cognitive skills grows over time because the effect of family SES on non-cognitive skills significantly increases over a child’s life-course. Our findings raise important questions regarding the role of non-cognitive skills in intergenerational social mobility. Cognitive and Non-cognitive Skills in Intergenerational Social Mobility 3 INTRODUCTION It is well understood that family background exerts strong influences on children’s educational outcomes, with children from higher-SES families academically outperforming those from lower-SES families (Becker 1993; Blau and Duncan 1967; Bourdieu 1977; Duncan and Brooks-Gunn 1997; Hauser, Tsai, and Sewell 1983; McLanahan and Sandefur 1994; Sewell, Haller, and Portes 1969). However, the question of how family SES actually affects children’s educational outcomes is still subject to debate. Broadly speaking, three categories of causal mechanisms have been considered: direct effects of hard resources, indirect effects through cognitive skills or “hard” skills measured by test scores, and indirect effects through noncognitive skills or personality traits which include a range of “soft” skills such as motivation, social skills and work habits. The first two causal mechanisms—the direct effect of family resources on achievement (Becker 1993; Mincer 1974; Kaushal, Magnuson, and Waldfogel 2011) and the indirect effect via cognitive skills (Griliches and Mason 1972; Jencks et al. 1979; Hauser, Tsai, and Sewell 1983; Sewell, Haller, and Portes 1969)—are well established. The role of non-cognitive skills in status attainment also has a long tradition in stratification research dating back to the Wisconsin socio-psychological model of status attainment (Hauser, Tsai and Sewell 1983; Sewell, Haller and Portes 1969). In recent years, however, their role has gained renewed interest. A growing body of research suggests that non-cognitive skills may be as important as cognitive skills in predicting a variety of outcomes, ranging from educational attainment (Duncan and Magnuson 2011; Lleras 2008; Rosenbaum 2001) to income and labor market performance (Cunha and Heckman 2009; Hall and Farkas 2011; Jackson 2006) to incarceration and teenage childbearing (Heckman, Stixrud and Urzua 2006). Moreover, sociological theories have long speculated that the family is instrumental in shaping critical non-cognitive skills that are important for future success, such as motivation, aspirations and self-discipline (Boudon 1974; Bourdieu 1977; Heckman 2006, 2011; Lareau 2003; Kao and Tienda 1995; Kim 2011; Goyette and Xie 1999). Yet to date, important questions remain about the role of non-cognitive skills in status attainment. While it is commonly accepted that non-cognitive skills, like cognitive skills, mediate the intergenerational transmission of family advantages or disadvantages, it is far from clear, a priori, that non-cognitive skills mediate the effects of family SES in the same manner as cognitive skills. Our current understanding is limited in at least two important ways. First, we do Cognitive and Non-cognitive Skills in Intergenerational Social Mobility 4 not know the relative importance of cognitive versus non-cognitive skills as mediators of family origin. For skills to mediate the effects of family SES on achievement outcomes, two conditions must hold: (1) they must affect achievement outcomes, and (2) family SES must affect them. To date, neither of these two relationships has been well established for non-cognitive skills. Second, most prior studies have taken a static conceptualization of skill formation by using single-point-in-time measures of skills (Duncan et al. 2007; Lleras 2008; Hauser, Tsai, and Sewell 1983; Jencks et al. 1979; Mood, Jonsson and Bihagen forthcoming; Sewell, Haller and Portes 1969). Growing evidence, however, suggests that the developmental trajectories of cognitive skills differ from those of non-cognitive skills. We do not know how these potential differences in the evolution of cognitive versus non-cognitive skills over the life-course might shape the ways in which they mediate family SES effects in different ways. To address these gaps in our understanding, we employ a two-step strategy. First, we decompose the impact of family background on children’s academic achievement into: (1) direct effects of family background and (2) indirect effects via cognitive and non-cognitive skills. We estimate these models alternatively using skills measured at kindergarten to 5 grade. This approach allows us to evaluate the relative importance of cognitive versus non-cognitive skills as mediators of family SES effects and to determine whether the mediating roles of these two types of skills change over time. Second, we use a variety of statistical techniques—including growth curve and fixed effect models—to explicitly determine the dynamic effects of family SES on trajectories of cognitive as well as non-cognitive skills. Doing so allows us to examine a potential reason why the mediating roles of cognitive and non-cognitive skills might change over time. Overall, we find that cognitive skills are stronger mediators of family SES than noncognitive skills. This is both because non-cognitive skills are less predictive of later achievement and because they are less affected by family SES. The later findings are particularly relevant because they suggest that the role of the family in shaping personality traits is weaker than previously theorized. When we take a developmental perspective and examine these relationships as they change over a child’s life course, we find that the mediating role of noncognitive skills increases over time, although they remain weaker mediators than cognitive skills. Moreover, the increase in the role that non-cognitive skills play over time can be attributed mainly to the increasing influence of family SES on non-cognitive skills. In other words, children’s non-cognitive skills are more sensitive to family environment at later ages. Cognitive and Non-cognitive Skills in Intergenerational Social Mobility 5 THEORETICAL AND METHODOLOGICAL ISSUES In Figure 1, we present a stylized conceptual model of status attainment. We revive the classical Wisconsin socio-psychological model as a starting point for understanding the causal pathways through which family SES influences children’s achievement outcomes (Hauser, Tsai, and Sewell 1983; Sewell, Haller and Portes 1969). In its original formulation, the Wisconsin model conjectures that the influence of family background on children’s status attainment is entirely mediated through children’s social-psychological traits defined as educational and occupational aspirations. We deviate from this position to include both a direct effect of family SES on children’s achievement outcomes and an indirect effect via children’s cognitive skills. In the following sections, we briefly review the literature pertaining to each of the three causal mechanisms linking family SES and children’s achievement (i.e., direct effects, indirect effect via cognitive skills and indirect effects via non-cognitive skills) and highlight the gaps in our knowledge. Figure 1: Stylized Model of Status Attainment Note. NC = Non-cognitive skills, SES = Mothers’ education and permanent family income Direct Effects of Family SES Family SES may exert direct effects on children’s educational outcomes because a higher family SES means more potential resources that could be expended to promote children’s education. The resource explanation has been popular in economics. According to this Cognitive and Non-cognitive Skills in Intergenerational Social Mobility 6 explanation, parents have an intrinsic “altruistic interest” in their children’s socioeconomic wellbeing and purposely invest in their children (Becker 1993; Mincer 1974). Parental investment in children may take a variety of forms, such as purchased goods and services (e.g., quality child care, school supplies and books, recreation and entertainment activities, and private lessons) and time spent on children (e.g., help with homework and attendance at school events) (Kaushal, Magnuson, and Waldfogel 2011). Note that these examples of parental investment are all about resources, in the sense that they are subject to firm budget constraints, and parents could divert their uses towards other uses (including other children) if withholding them from a particular child. Indirect Effects through Cognitive Skills Another main causal pathway through which family SES affects children’s educational outcomes is via cognitive abilities, also called “hard skills.” We do not yet know the true extent to which cognitive abilities are determined by nature (i.e. genetics) versus nurture (i.e. environment), but it is safe to say that the two forces interact in certain ways that shape one’s cognitive abilities (e.g., Nisbett 2009; Plomin, Defries, and Loehlin 1977). Studies show that the most important period for cognitive sk