"Birth weight has emerged as the leading indicator of infant health and welfare and the central focus of infant health policy. This is because low birth weight (LBW) infants experience severe health and developmental difficulties that can impose enormous costs on society. But would the prevention of LBW generate equally sizable cost savings and health improvements? Estimates of the return to LBW-prevention from cross-sectional associations may be biased by omitted variables that cannot be influenced by policy, such as genetic factors. To address this, we compare the hospital costs, health at birth, and infant mortality rates between heavier and lighter infants from all twin pairs born in the United States. We also examine the effect of maternal smoking during pregnancy the leading risk factor for LBW in the United States on health among singleton births after controlling for detailed background characteristics. Both analyses imply substantially smaller effects of LBW than previously thought, suggesting two possibilities: 1) existing estimates overstate the true costs and consequences of LBW by at least a factor of four and by as much as a factor of 20; or 2) different LBW-preventing interventions have different health and cost consequences, implying that policy efforts that presume a single return to reducing LBW will necessarily be suboptimal"--National Bureau of Economic Research web site.

This study uses sharp, differential air quality changes across sites attributable to geographic variation in the effects of the 1981-82 recession to estimate the relationship between infant mortality and particulates air pollution. It is shown that in the narrow period of 1980-82, there was substantial variation across counties in changes in particulates pollution, and that these differential pollution reductions appear to be orthogonal to changes in a multitude of other factors that may be related to infant mortality. Using the most detailed and comprehensive data available, we find that a 1 mg/m3 reduction in particulates results in about 4-8 fewer infant deaths per 100,000 (a 0.35-0.45 elasticity). The estimated effects are driven almost entirely by fewer deaths occurring within one month and one day of birth, suggesting that fetal exposure to pollution has adverse health consequences. The estimated effects of the pollution reductions on infant birth weight provide evidence consistent with this potential pathophysiologic mechanism. The analysis also reveals a nonlinear relationship between pollution and infant mortality at the county level. Importantly, the estimates are remarkably stable across a variety of specifications. All of these findings are masked in conventional' analyses based on less credible research designs

Chay, Guryan and Mazumder (2009) found substantial racial convergence in AFQT and NAEP scores across cohorts born in the 1960's and early 1970's that was concentrated among blacks in the South. We demonstrated a close tracking between variation in the test score convergence across states and racial convergence in measures of health and hospital access in the years immediately after birth. This study analyzes whether the across-cohort patterns in the black-white education and earnings gaps match those in early life health and test scores already established. It also addresses caveats in the earlier study, such as unobserved selection into taking the AFQT and potential discrepancies between state-of-birth and state-of-test taking. With Census data, we find: i) a significant narrowing across the same cohorts in education gaps driven primarily by a relative increase in the probability of blacks going to college; and ii) a similar convergence in relative earnings that is insensitive to adjustments for employment selection, as well as time and age effects that vary by race and state-of-residence. The variation in racial convergence across birth states matches the patterns in the earlier study. The magnitude of the earnings gains is greater than can be explained by only the black gains in education and test scores for reasonable estimates of the returns to human capital. This suggests that other pre-market, productivity factors also improved across successive cohorts of blacks born in the South between the early 1960's and early 1970's. Finally, our cohort-based hypothesis provides a cohesive explanation for the aggregate patterns in several, previously disconnected literatures.

The role of social status in life expectancy is a burgeoning topic of interest in health research. Isolating the impact of "pure status" on longevity is empirically challenging as an individual's ranking within the social hierarchy is related to other SES measures (e.g. education, income) which are correlated with health. Previous work is based either on animal studies (e.g. Sapolksy's work on baboons) or studies of humans in unique non-experimental settings (e.g. British Civil Servants: Academy Awards and Nobel Prize winners). We use the precise rules for induction into the Baseball Hall of Fame to examine the impact of status attainment (or non-attainment) on life expectancy. The Baseball Hall of Fame provides a compelling context since the selection rule for induction by the Baseball Writers Association of America (BBWAA) is perfectly observed - a BBWAA vote share of 75 percent or more. We explore whether this discontinuous rule for assigning status leads to differential exposure to stress depending on proximity to the cut-off. We obtain BBWAA voting data from the Baseball Hall of Fame website (www.baseballhalloffame.org). For each player born prior to 1946 (n=597) we use complete voting histories to construct a series of variables used in our analysis. From membership lists on the Hall of Fame website we construct indicators denoting whether a player was inducted by the BBWAA or the Committee on Baseball Veterans. From two other websites (www.baseball-reference.com, www.baseball-almanac.com) we obtain player characteristics including exact dates of birth/death, height/weight, ethnicity and education. Finally, we categorize cause of death using obituaries found through Lexis-Nexis, and a book on the necrology of baseball players. We estimate the impact of Hall of Fame induction and the number of narrow losses (vote share>50%) on life expectancy, controlling for each player's maximum vote share, the number of ballot appearances, and demographic characteristics. We use several parametric (Tobit MLE, Buckley-James) and non-parametric (Kaplan-Meier survivor analysis) methods to correct for right censoring in the life durations of players who are still alive. The effect of induction on longevity depends both on the definition of the reference group and the ease of induction. BBWAA inductees do not live longer, on average, than players who were not inducted. However, they do live 10 percent longer than players who narrowly missed induction through the BBWAA. This results from the reduced life expectancies of players who narrowly missed induction relative to non-inductees with lower BBWAA vote shares. Life expectancy falls by 3 percent for each ballot with a vote share over 50 percent but below the 75 percent threshold required for induction. Hall of Fame induction through the Veteran's Committee increases life expectancy, with the largest effect among players who never received a BBWAA ballot share above 10 percent. The effect sizes of the Hall of Fame variables are much larger in magnitude than the effects of BMI, year of birth, and educational attainment (i.e., college matriculation). Our results suggest that the anxiety induced by non-attainment or delayed attainment of status can lead to premature death - with heart attacks being the predominant cause of death - and that there are health benefits of status attained through 'luck' rather than through performance.

We examine the effects of total suspended particulates (TSPs) air pollution on infant health using the air quality improvements induced by the 1970 Clean Air Act Amendments (CAAA). This legislation imposed strict regulations on industrial polluters in "nonattainment" counties with TSPs concentrations exceeding the federal ceiling. We use nonattainment status as an instrumental variable for TSPs changes to estimate their impact on infant mortality changes in the first year that the 1970 CAAA was in force. TSPs nonattainment status is associated with sharp reductions in both TSPs pollution and infant mortality from 1971 to 1972. The greater reductions in nonattainment counties near the federal ceiling relative to the "attainment" counties narrowly below the ceiling suggest that the regulations are the cause. We estimate that a one percent decline in TSPs results in a 0.5 percent decline in the infant mortality rate. Most of these effects are driven by a reduction in deaths occurring within one month of birth, suggesting that fetal exposure is a potential biological pathway. The results imply that roughly 1,300 fewer infants died in 1972 than would have in the absence of the Clean Air Act.

One literature documents a significant, black-white gap in average test scores, while another finds a substantial narrowing of the gap during the 1980's, and stagnation in convergence after. We use two data sources -- the Long Term Trends NAEP and AFQT scores for the universe of applicants to the U.S. military between 1976 and 1991 -- to show: 1) the 1980's convergence is due to relative improvements across successive cohorts of blacks born between 1963 and the early 1970's and not a secular narrowing in the gap over time; and 2) the across-cohort gains were concentrated among blacks in the South. We then demonstrate that the timing and variation across states in the AFQT convergence closely tracks racial convergence in measures of health and hospital access in the years immediately following birth. We show that the AFQT convergence is highly correlated with post-neonatal mortality rates and not with neonatal mortality and low birth weight rates, and that this result cannot be explained by schooling desegregation and changes in family background. We conclude that investments in health through increased access at very early ages have large, long-term effects on achievement, and that the integration of hospitals during the 1960's affected the test performance of black teenagers in the 1980's.

Several countries have implemented programs that use test scores to rank schools, and to reward or penalize them based on their students' average performance. Recently, Kane and Staiger (2002) have warned that imprecision in the measurement of school-level test scores could impede these efforts. There is little evidence, however, on how seriously noise hinders the evaluation of the impact of these interventions. We examine these issues in the context of Chile's P-900 program a country-wide intervention in which resources were allocated based on cutoffs in schools' mean test scores. We show that transitory noise in average scores and mean reversion lead conventional estimation approaches to greatly overstate the impacts of such programs. We then show how a regression discontinuity design that utilizes the discrete nature of the selection rule can be used to control for reversion biases. While the RD analysis provides convincing evidence that the P-900 program had significant effects on test score gains, these effects are much smaller than is widely believed.

We examine the roles of sample initial conditions and unobserved individual effects in consistent estimation of the dynamic binary response panel data model. Different specifications of the model are estimated using female welfare and labor force participation data from the Survey of Income and Program Participation (SIPP). These include alternative random effects models, in which the conditional distributions of both the unobserved heterogeneity and the initial conditions are specified, and fixed effects conditional logit models that make no assumptions on either distribution. There are several findings. First, the hypotheses that the sample initial conditions are either exogenous or in equilibrium are rejected by the data. Misspecification of the initial conditions results in drastically overstated estimates of the state dependence and understated estimates of the short- and long-run effects of children on labor force participation. The fixed effects conditional legit estimates are similar to the estimates from the random effects model that is flexible with respect to both the initial conditions and the correlation between the unobserved heterogeneity and the covariates. Heterogeneity appears to explain about 50% and 70% of the overall persistence in welfare and labor force participation, respectively. In addition, for female labor force participation, there is evidence that fertility choices are correlated with both unobserved heterogeneity and pre-sample participation histories.