What Doesn't Kill you Makes you Weaker: Prenatal Pollution Exposure and Educational Outcomes

I examine the impact of prenatal suspended particulate pollution on educational outcomes, using ambient total suspended particulates (TSPs) as a measure of particulate exposure and standardized test scores of exposed individuals as a measure of educational achievement. I focus on individuals born between 1979 and 1985 to exploit the shock of the industrial recession of the early 1980s. This variation helps separate the causal effects of pollution reduction from general time trends. Considering the 7-year time period as a whole yields statistically insignificant results, but focusing on the 3-year period around the recession (1981-1983) yields negative and statistically significant results, suggesting that the relationship is subtle enough to require large-scale changes to be detectable. My findings suggest a standard deviation decrease in the mean pollution level in a student’s year of birth is associated with 1.87% of a standard deviation increase in test scores in high school. I also employ an instrumental variables strategy, using changes in relative manufacturing employment driven by the recession as an instrument for TSP levels. Instrumental variables results are approximately 3.7 times the size of the OLS results, suggesting the potential presence of measurement error in ambient pollution. Results are robust to the inclusion of school fixed effects, year of birth and year of test fixed effects, and various demographic and economic covariates. I also investigate the potential bias sources of migration and selection into motherhood, and show these are unlikely to explain my results.motherhood, education

Verifiable and Non-Verifiable Anonymous Mechanisms for Regulating a Polluting Monopolist

Optimal regulation of a polluting natural monopolist must correct for both external damages and market power to achieve a social optimum. Existing non-Bayesian regulatory methods require knowledge of the demand function, while Bayesian schemes require knowledge of the underlying cost distribution. We introduce mechanisms adapted to use less information. Our Price-based Subsidy (PS) mechanisms give the firm a transfer that matches or approximates the incremental surplus generated each period. The regulator need not observe the abatement activity or know the demand, cost, or damage functions of the firm. All of the mechanisms induce the firm to price at marginal social cost, either immediately or asymptotically.surplus subsidy schemes, polluting monopolist, verifiable regulatory mechanisms

Verifiable and Non-Verifiable Anonymous Mechanisms for Regulating a Polluting Monopolist

Optimal regulation of a polluting natural monopolist must correct for both external damages and market power to achieve a social optimum. Existing non-Bayesian regulatory methods require knowledge of the demand function, while Bayesian schemes require knowledge of the underlying cost distribution. We introduce mechanisms adapted to use less information. Our Price-based Subsidy (PS) mechanisms give the firm a transfer that matches or approximates the incremental surplus generated each period. The regulator need not observe the abatement activity or know the demand, cost, or damage functions of the firm. All of the mechanisms induce the firm to price at marginal social cost, either immediately or asymptotically

Where Have All the Young Men Gone? Using Gender Ratios to Measure Fetal Death Rates

Fetal health is an important consideration in the formation of health-based policy. However, a complete census of true fetal deaths is impossible to obtain. We present the gender ratio of live births as an under-exploited metric of fetal health and apply it to examine the effects of air quality on fetal health. Males are more vulnerable to side effects of maternal stress in utero, and thus are more likely to suffer fetal death due to pollution exposure. We demonstrate this metric in the context of the Clean Air Act Amendments of 1970 (CAAA) which provide a source of exogenous variation in county-level ambient total suspended particulate matter (TSPs). We find that a standard deviation increase in annual average TSPs (approximately 35 μg/m 3) decreases the percentage of live births that are male by 3.1 percentage points. We then explore the use of observed differences in neonatal and one-year mortality rates across genders in response to pollution exposure as a metric to estimate total fetal losses in utero. These calculations suggest the pollution reductions from the CAAA prevented approximately 21,000-134,000 fetal deaths in 1972.

Ability, gender, and performance standards: Evidence from academic probation

We use a regression discontinuity design to examine students\u27 responses to being placed on academic probation. Consistent with a model of introducing performance standards, we find that being placed on probation at the end of the first year discourages some students from returning to school while improving the GPAs of those who do. We find heterogeneous responses across prior academic performance, gender, and native language, and discuss these results within the context of the model. We also find negative effects on graduation rates, particularly for students with the highest high school grades

Caution, Drivers! Children Present: Traffic, Pollution, and Infant Health

Since the Clean Air Act Amendments of 1990 (CAAA), atmospheric concentration of local pollutants has fallen drastically. A natural question is whether further reductions will yield additional health benefits. We further this research by addressing two related research questions: (1) what is the impact of automobile driving (and especially congestion) on ambient air pollution levels, and (2) what is the impact of modern air pollution levels on infant health? Our setting is California (with a focus on the Central Valley and Southern California) in the years 2002-2007. Using an instrumental variables approach that exploits the relationship between traffic, ambient weather conditions, and various pollutants, our findings suggest that ambient pollution levels, specifically particulate matter, still have large impacts on weekly infant mortality rates. Our results also illustrate the importance of weather controls in measuring pollution’s impact on infant mortality.University of California Energy Institute and UC Davis Institute of Transportation Studies. UC Davis Institute of Governmental Affairs, the UC Davis Institute of Transportation Studies, and the TSR&TP through the Atmospheric Aerosols and Health (AAH) Lead Campus program

Ability, Gender, and Performance Standards: Evidence from Academic Probation

We use a regression discontinuity design to examine students' responses to the negative incentive brought on by being placed on academic probation. Consistent with a model of introducing performance standards in which agents respond differently based on ability, we find that being placed on probation at the end of the first year discourages some students from returning to school while improving the performance of those who return. Contrary to the predictions of the model when ability is known, we find that heterogeneous discouragement effects result in high ability students having a greater overall dropout rate near the cutoff than lower ability students. The result can be explained by extending the model to allow for the performance standard to also affect self confidence (ability expectations). We also consider effects by gender and find that being placed on probation more than doubles the probability that men drop out but has no such discouragement effect for women.

Counting ants (Hymenoptera: Formicidae): Biodiversity sampling and statistical analysis for myrmecologists

Biodiversity sampling is labor intensive and is especially challenging for myrmecologists, because the sampling units (individual workers) do not correspond in a simple way to the natural units of diversity (individual nests). Because it is usually not possible to reach a sampling asymptote for ants, comparisons of species richness among collections have to be carefully standardized for the number of individuals and number of samples examined. Asymptotic estimators allow for extrapolation to an estimated asymptote of species richness, and rarefaction curves permit meaningful comparisons of samples by interpolating data to a standardized number of sampling units. Winkler sacks of leaf litter and specialized traps for arboreal ants often yield distinctive sets of species in tropical and subtropical latitudes. These microhabitats are best treated as distinctive assemblages that can be compared with stratified sampling. Within other habitat types, different baiting and sampling methods yield similar, but not identical sets of species, and many authors have advocated using a diversity of methods to gain the greatest coverage of species. However, many of the distinctive species that are sampled by a particular method are rare, and are just as likely to have been found with other sampling methods. The estimated similarity in composition of ants sampled by different methods in the same habitat is probably greater than has been appreciated. Recent published comparisons of sampling efficiency have shown that hand collecting accumulates species more efficiently than the more commonly used pitfall traps or baits. However, if hand-collected samples are to be analyzed quantitatively, hand sampling must be standardized to a constant plot size that is searched for a fixed amount of time, and all nests encountered must be sampled and counted. For comparative studies of ant assemblages across habitats, hand collecting may be superior to either litter sampling or pitfall traps because it can be used in sites that have no leaf litter or are too environmentally sensitive, too rocky, too steep, or contain too much human and domestic animal traffic for pitfall trapping. Data from hand sampling and grids of pitfall traps lend themselves to slightly different kinds of analyses. Hand sampling probably gives the best estimates of the true frequency of nests of different species in an area, and the data can be used with individual-based rarefaction curves and many standard parametric statistical tests. Data from pitfalltrap grids should usually be treated as sample-based occurrences, and analyzed with sample-based rarefaction and diversity estimators. For the purposes of estimating diversity, myrmecologists should avoid the temptation to analyze the underlying counts of individual workers. Data from replicated grids of pitfall traps can be analyzed with hierarchical occupancy models. These newly developed models provide useful estimates of probabilities of occurrence and probabilities of detection for each species in the assemblage. Biogeographic patterns of ant diversity, such as latitudinal gradients of species richness, are comparable to those seen in other taxa, and the data collected by myrmecologists can contribute in important ways to our general understanding of biodiversity patterns