We address leadership emergence and the possibility that there is a partially innate predisposition to occupy a leadership role. Employing twin design methods on data from the National Longitudinal Study of Adolescent Health, we estimate the heritability of leadership role occupancy at 24%. Twin...

We explore the influence of genetic variation on subjective well-being by employing a twin design and genetic association study. In a nationally representative twin sample, we first show that 33% of the variation in life satisfaction is explained by genetic variation. Although previous studies...

Peers have a powerful effect on adolescents’ beliefs, attitudes, and behaviors. Here, we examine the role of social networks in the spread of attitudes towards sexuality using data from the National Longitudinal Study of Adolescent Health (Add Health). Although we found evidence that both...

OBJECTIVE: To describe the relative importance of health care market structure and county-level demographics in determining rates of hospice use. DATA SOURCES: Medicare claims data for a cohort of elderly patients newly diagnosed with lung cancer, colon cancer, stroke, or heart attack in 1993,...

Using a discovery and replication sample from a U.S. representative data set, we show that a functional polymorphism on the MAOA gene is associated with credit card borrowing behavior. For the combined sample of approximately 12,000 individuals we find that having one or both MAOA alleles of the...

A large part of the recent literature on program evaluation has focused on estimation of theaverage effect of the treatment under assumptions of unconfoundedness or ignorability following the seminal work by Rubin (1974) and Rosenbaum and Rubin (1983). In many cases however, researchers are...

Properties of GMM estimators are sensitive to the choice of instruments. Usingmany instruments leads to high asymptotic asymptotic efficiency but can causehigh bias and/or variance in small samples. In this paper we develop and implementasymptotic mean square error (MSE) based criteria for...

The otherwise straightforward analysis of randomized experiments is often complicated by the presence of missing data. In such situations it is necessary to make assumptions about the dependence of the selection mechanism on treatment, response, and covariates. The widely used approach of...