"Diffusion in Social Networks: New Theory and Experiments "

ABSTRACT

The strength of weak ties is that they tend to be long – they connect socially distant locations. Research on “small worlds” shows that these long ties can dramatically reduce the “degrees of separation” of a social network, thereby allowing ideas and behaviors to rapidly diffuse. However, I show that the opposite can also be true. Increasing the frequency of long ties in a clustered social network can also inhibit the diffusion of collective behavior across a population. For health related behaviors that require strong social reinforcement, such as dieting, exercising, smoking cessation, or even condom use, successful diffusion may depend primarily on the width of bridges between otherwise distant locations, not just their length. I present formal and computational results that demonstrate these findings, and then present an experimental test of the effects of social network topology on the diffusion of health behavior.

"New Thoughts on Old Age "

ABSTRACT

I will discuss late-age career transitions and retirement incentive plans, the annuity puzzle, and financial issues that are faced by the aging population. My discussion aims to stimulate new thoughts and argument about aging and retirement.

"Research Funding and the Foreign Born "

ABSTRACT

There has been a resurgence of interest in the link between immigration and economic activity. The evidence suggests that US education plays an important role in both attracting and retaining high-quality foreign-born students. This is particularly true in the case of doctorates trained in science, technology, engineering and mathematics (STEM), a workforce that is disproportionately foreign born and likely to contribute to long-term economic growth. Because of this, much effort is given toward attracting talented students and retaining them in the US workforce after they complete their studies. However, little is known about how that attraction and retention works. In this paper we use new data to examine the role of an important policy lever-research funding—in keeping both domestic and foreign-born workers in the US labor market.

"The Problem of Causal Mutualisms, The Promise of Polygenic Scores, and The Pervasive Divergence of Life Outcomes"

ABSTRACT
Casual mutualisms are sets of properties that have substantial reciprocal influence on one another. This may sound abstruse, but various big constructs in behavioral science, including "heritability," "SES", "health", and "achievement," exhibit clear signs of instantiating massive mutualisms and yet many implications of their doing so remain largely unpursued. The talk will describe the problem and several routes into it by reference to a series of phenomena that might otherwise appear unrelated, on intellectual achievement, educational attainment, and health disparities. Together these examples are used to argue for a more strongly integrative and developmental social science, as well as the potential value of predictive scores based on genomic information for helping reckon with mutualisms.

"Harnessing Social Networks and Social Systems for Obesity Prevention"

ABSTRACT

Our health and social networks are closely intertwined. In this talk, I describe how the complex web of family, friend, and peer relationships in which we are embedded—i.e., our social networks– influence eating, physical activity, and obesity, and how the dynamics of our evolving behaviors and social networks shape population obesity rates. I will outline intervention and policy strategies that have the potential to activate, harness, or alter social networks and broader social-ecological systems, so that these social contexts play a more supportive role in the prevention and treatment of obesity.

"Legal Origins and Female HIV "

ABSTRACT

More than half of all people living with HIV are women and 80% of all HIV positive women in the world live in Sub-Saharan Africa. This paper demonstrates that the legal origins of these formally colonized countries significantly determines current day female HIV rates. In particular, female HIV rates are significantly higher in common law Sub-Saharan African countries compared to Civil law ones. This paper explains this relationship by focusing on differences in female property rights under the two codes of law. In Sub-Saharan Africa, common law is associated with weaker female marital property laws. As a result, women in these common law countries have lower bargaining power within the household and are less able to negotiate safer sex and are thus more vulnerable to HIV, compared to their civil law counterparts. Exploiting the fact that some ethnic groups in Sub-Saharan Africa cross country borders with different legal systems, we are able to include ethnicity fixed effects into a regression discontinuity approach. This allows us to control for a large set of cultural, geographical, and environmental factors that could be confounding the estimates. The results of this paper are consistent with gender inequality (the ‘feminization of AIDS’) explaining much of its prevalence in Sub-Saharan Africa.

"To Work for Yourself, for Others, or Not at All? How Disability Benefits Affect The Employment Decisions of Older Veterans "

ABSTRACT
The U.S. Department of Veterans Affairs Disability Compensation (DC) program provides disability benefits to nearly one in five military veterans in the US and its annual expenditures exceed $60 billion. We examine how the receipt of DC benefits affects the employment decisions of older veterans. We make use of variation in program eligibility resulting from a 2001 policy change that increased access to the program for Vietnam veterans who served with “boots on the ground” in the Vietnam theater but not for other veterans of that same era. We find that the policy-induced increase in program enrollment decreased labor force participation and induced a substantially larger switch from wage employment to self-employment. This latter finding suggests that an exogenous increase in income spurred many older veterans to start their own businesses. Additionally, we estimate that one in four veterans who entered the DC program due to this policy change left the labor force, estimates in the same range as those from recent studies of the Social Security Disability Insurance (SSDI) program.

"Early-Life Undernourishment in Developing Countries: Prevalence, Impacts over the Life Cycle and Determinants"

ABSTRACT

Early-life undernourishment is a widespread phenomenon in many developing countries, with an estimated 170 million children under 5 years of age stunted, the standard indicator of chronic malnutrition. This presentation summarizes an ongoing work program on this topic, with reference to the prevalence, impacts and determinants of such undernutrition.

"Tuskegee and the Health of Black Men"

ABSTRACT
For forty years, the Tuskegee Study of Untreated Syphilis in the Negro Male passively monitored hundreds of adult black males with syphilis despite the availability of effective treatment. The study's methods have become synonymous with exploitation and mistreatment by the medical community. We find that the historical disclosure of the study in 1972 is correlated with increases in medical mistrust and mortality and decreases in both outpatient and inpatient physician interactions for older black men. Our estimates imply life expectancy at age 45 for black men fell by up to 1.4 years in response to the disclosure, accounting for approximately 35% of the 1980 life expectancy gap between black and white men.

"Refund Anticipation Products and the Improper Payment of the EITC."