Tripartite structural analysis: Generalizing the Breiger-Wilson formalism

Tripartite graphs have three types of nodes and ties exist only between nod this paper, we indicate the background of work in structural analysis that leads to the use of such graphs and we develop the associated matrix methods. Fundamentally, the idea is to move another step forward in our ability to treat in analytical terms the general phenomenon of overlapping inclusions, such as that of persons and groups. We relate this idea to classic concerns with the interpenetration of persons, social systems, and cultural systems. In detail, the framework and results generalize those of Breiger (1974) and Wilson (1982).     

Intake fraction for multimedia pollutants: a tool for life cycle analysis and comparative risk assessment.

We employ the intake fraction (iF) as an effective tool for expressing the source-to-intake relationship for pollutant emissions in life cycle analysis (LCA) or comparative risk assessment. Intake fraction is the fraction of chemical mass emitted into the environment that eventually passes into a member of the population through inhalation, ingestion, or dermal exposure. To date, this concept has been primarily applied to pollutants whose primary route of exposure is inhalation. Here we extend the use of iF to multimedia pollutants with multiple exposure pathways. We use a level III multimedia model to calculate iF for TCDD and compare the result to one calculated from measured levels of dioxin toxic equivalents in the environment. We calculate iF for emissions to air and surface water for 308 chemicals. We correlate the primary exposure route with the magnitudes of the octanol-water partition coefficient, Kow, and of the air-water partitioning coefficient (dimensionless Henry constant), Kaw. This results in value ranges of Kow and Kaw where the chemical exposure route can be classified with limited input data requirements as primarily inhalation, primarily ingestion, or multipathway. For the inhalation and ingestion dominant pollutants, we also define empirical relationships based on chemical properties for quantifying the intake fraction. The empirical relationships facilitate rapid evaluation of many chemicals in terms of the intake. By defining a theoretical upper limit for iF in a multimedia environment we find that iF calculations provide insight into the multimedia model algorithms and help identify unusual patterns of exposure and questionable exposure model results.     

Family Structure and Early Home Leaving: A Mediation Analysis

An ample body of research has shown that young adults from non-intact families are more likely to leave the parental home at an early age than young adults from intact families. However, little is known about the mechanisms underlying this relationship. We drew on prospective longitudinal data from the German Socio-Economic Panel Study (SOEP) to examine why young adults from non-intact families are more likely to leave home early. Based on the feathered nest hypothesis, it was expected that young adults from non-intact families are pushed out of the parental home because of a lack in economic, social, and community resources. Moreover, it was expected that young adults from non-intact families are pulled toward independent living at a younger age because they have a partner and are employed earlier in life. We employed discrete-time event history models and used the KHB method to test relative weights of the mediators. The mediators explained 16% (women) and 22% (men) of the effect of living in a stepfamily, and 50% (women) and 37% (men) of the effect of living in a single-mother family. Economic resources were the main mediator for the effect of living in a single-mother family on early home leaving. For women, mother’s life satisfaction and housing conditions significantly explained differences in early home leaving between single-mother and intact families. For men, residential mobility significantly mediated the effect of family structure on early home leaving.     

Medicaid Expansions and Fertility in the United States

Beginning in the mid-1980s and extending through the early to mid-1990s, a substantial number of women and children in the United States gained eligibility for Medicaid through a series of income-based expansions. Using natality data from the National Center for Health Statistics, we estimate fertility responses to these eligibility expansions. We follow Currie and Gruber (2001) and measure changes in state Medicaid-eligibility policy by simulating the fraction of a standard population that would qualify for benefits in different states and different time periods. From 1985 to 1996, the fraction of women aged 15–44 who were eligible for Medicaid coverage for a pregnancy increased more than 20 percentage points. When we use a state and year fixed-effects model with a limited set of covariates, our estimates indicate that fertility increases in response to Medicaid expansions. However, after we include fixed effects for demographic characteristics, the estimated relationship diminishes substantially in size and is no longer statistically significant. We conclude that there is no robust relationship between Medicaid expansions and fertility.     

On Nonstable and Stable Population Momentum

This article decomposes total population momentum into two constituent and multiplicative parts: “nonstable” momentum and “stable” momentum. Nonstable momentum depends on deviations between a population’s current age distribution and its implied stable age distribution. Stable momentum is a function of deviations between a population’s implied stable and stationary age distributions. In general, the factorization of total momentum into the product of nonstable and stable momentum is a very good approximation. The factorization is exact, however, when the current age distribution is stable or when observed fertility is already at replacement. We provide numerical illustrations by calculating nonstable, stable, and total momentum for 176 countries, the world, and its major regions. In short, the article brings together disparate strands of the population momentum literature and shows how the various kinds of momentum fit together into a single unifying framework.     

Transition to Parenthood: The Role of Social Interaction and Endogenous Networks

Empirical studies indicate that the transition to parenthood is influenced by an individual’s peer group. To study the mechanisms creating interdependencies across individuals’ transition to parenthood and its timing, we apply an agent-based simulation model. We build a one-sex model and provide agents with three different characteristics: age, intended education, and parity. Agents endogenously form their network based on social closeness. Network members may then influence the agents’ transition to higher parity levels. Our numerical simulations indicate that accounting for social interactions can explain the shift of first-birth probabilities in Austria during the period 1984 to 2004. Moreover, we apply our model to forecast age-specific fertility rates up to 2016.     

The rise and fall of civil unions: lessons from the Connecticut legislature's abandonment of gay and lesbian citizens

On April 20, 2005, Connecticut Governor M. Jodi Rell signed into law "An Act Concerning Civil Unions" (Public Act No. 05-10, 2005). That Act did two things: First, it afforded to qualifying same-sex couples many of the rights and benefits that the state makes available to married heterosexual couples. Second, it "defended" heterosexual marriage by defining marriage as involving one man and one woman. Although it might seem that the legislature was moving in an obviously correct direction, its decision to establish a statutory scheme consigning same-sex couples to civil unions was integral to the ideological exclusion of gays and lesbians from marriage and, thereby, implied that they are unfit for family life. The Democrats' and Republicans' focus was on the formal equality guaranteed by the civil union legislation. But the heart of the legislation is disenfranchisement. Connecticut lawmakers placed the stamp of legitimacy on a policy that officially excluded lesbians and gays from full membership in civil society. To many gay and lesbian citizens in Connecticut, it was a slap in the face and awakened a realization that lawmakers' professed egalitarian ideals and the realities of defining who belonged to their communities may not coincide.     

The savings behavior of temporary and permanent migrants in Germany

This paper examines the relative savings position of migrant households in West Germany paying particular attention to differences between temporary and permanent migrants. Our findings reveal significant differences in the savings rates between German natives and immigrants. If remittances are treated as savings, however, migrants who intend to return to their home country save significantly more than comparable natives. The results of a decomposition analysis indicate that slightly more than half of the differences in the savings rate between Germans and permanent migrants and almost 70% between temporary and permanent migrants can be attributed to differences in observable characteristics.     

The optimum growth rate for population under critical-level utilitarianism

We characterize optimal consumption, capital, and population growth of a production economy under critical-level utilitarianism. First, we show that neither classical utilitarianism nor average utilitarianism can avoid a corner solution for the population growth rate, in that under the former, population grows at the maximum speed (the so-called repugnant conclusion) while under the latter, it grows at the minimum. Second, we show that critical level utilitarianism yields an interior solution for the population growth rate provided the critical level belongs to a positive, open interval. Finally, we characterize the transition to the steady state and perform comparative dynamics analysis.