A major justification for devoting resources to the study of public health is the potential to answer questions about the burden of poor health, both in terms of the total burden faced by individuals and the burden placed upon publicly funded social insurance programs. Indeed, the adequate provision of social insurance programs is one of the key policy issues of our day. A potentially fruitful approach in undertaking this effort is to investigate the effects of specific chronic diseases and injuries upon program participation and benefit levels. Ideally, we would like to know something about the total economic costs of individual diseases using theoretically sound willingness-to-pay measures. In practice, however, willingness-to-pay measures cannot be estimated with most available health data. Though this paper cannot pin down anything as ambitious as the total economic burden of disease, it does address the narrower but still important question of what is the burden of chronic illness upon Social Security Disability Insurance (SSDI) payments, and it documents how that burden has shifted between different disease groups over the past century. Furthermore, it addresses, at least to a limited extent, the profound intellectual question of what determines disability and how biomedical, economic, social, and institutional factors determine whether an individual will be disabled. In this paper we begin an exploration of newly collected data on the health conditions and disability benefits of Union Army VeteransI and make comparisons to recipients of disability benefits in more recent tinmes. We find two main results. The first is that there has been a significant shift in the types of diseases that lead to disability, both in terms of prevalence rates and benefit levels. The second is more surprising: the disabled in modern times generally have a greater number of chronic illnesses than did disabled Union Army veterans, even those who were severely disabled. This result implies a way of thinking about disease and disability that deserves more research attention. In short, prior to the advent of modem medicine and the concurrent reductions in the physical demands of work, people became disabled not because they had numerous chronic illnesses (i.e., high rates of co-morbidity), but because individual conditions (even ones as simple as hernias or hemorrhoids) had much more severely debilitating effects on health and upon the capacity to work than those same conditions do today.

Studies have demonstrated that classroom experiments have a positive effect on student achievement in economics courses. Questions remain regarding the appropriate number of experiments. In the current study we attempt to determine whether more intensive use of classroom experiments is associated with greater student achievement. Our data contains variation in the number of experiments administered in a principles of microeconomics course. We find that participation in classroom experiments has a positive, but diminishing, marginal benefit on students' final course scores. We also find that classroom experiments can bridge some achievement gaps (between older and younger students, between whites and minorities).

We investigate the effects of automobile congestion on ambient air pollution and local infant mortality rates using data from California spanning 2002 to 2007. Constructing instrumental variables (IV) using the relationship of traffic, weather conditions, and pollutants, we show that particulate matter, even at modern levels, has large marginal effects on weekly infant mortality rates, especially for premature or low birthweight infants. We also find suggestive evidence of large effects for carbon monoxide, though results are imprecise. Finally, we check estimate sensitivity to nonclassical measurement error in local pollution and show that our IV results are robust to such concerns.

Expensive infrastructure is ineffective if it doesn't travel the last mile. In nineteenth-century New York and modern Africa, disease has spread when urbanites chose not to use newly built sanitation infrastructure to save money. Either subsidies or Pigouvian fines can internalize the externalities that occur when people don't use sanitation infrastructure, but with weak institutions subsidies generate waste and fines lead to extortion. Our model illustrates the complementarity between infrastructure and institutions and shows how institutional weaknesses determine whether fines, subsidies, both or neither are optimal. Contrary to Becker (1968), the optimal fine is often mild to reduce extortion.

We use events related to a proxy access rule passed by the Securities and Exchange Commission in 2010 as natural experiments to study the valuation effects of changes in shareholder control. We find that valuations increase (decrease) following increases (decreases) in perceived control, especially for firms that are poorly performing, have shareholders likely to exercise control, and where acquiring a stake is relatively inexpensive. These results suggest that an increase in shareholder control from its current level would generally benefit shareholders. However, we find that the benefits of increased control are muted for firms with shareholders whose interests may deviate from value maximization.

People make personal plans regarding whether, when, where, and how to undertake certain actions. We discuss three questions related to personal plans. First, what are the effects of plans on behavior? Second, when are plans formed? Third, how do plans deviate from optimality? For each of these questions, we (a) offer a brief overview of research that sheds light on the issue and (b) identify gaps in current knowledge. We emphasize connections to the growing theoretical literature that gives personal plans a substantive role, but we conclude that more research is needed, especially on the latter two questions we cover.