The Impact of College Course Offerings on the Supply of Academically Talented Public School Teachers

University of Michigan forthcoming in the Journal of Econometrics This paper identifies the impact of undergraduate teacher certification programs on the likelihood that recent college graduates enter and remain in public school teaching jobs. More selective postsecondary institutions are far less likely to offer teacher certification programs and those that do offer them are less likely to allow students to complete them within their four undergraduate years. First, to examine the overall relationship between the availability of teacher certification programs and the likelihood that academically talented students enter teaching careers, I combine Barron's ratings of college selectivity, detailed data tracking college seniors into the workforce, data on the types of teacher certification programs offered by their colleges, and data on states' certification requirements. Next, to isolate the causal effect of program offerings, I treat the selection issue related to students sorting into colleges based on pre-existing interest in teaching careers as an omitted variable problem. Using another data set that surveys high school seniors' career interests and tracks them into college, I estimate an upper bound for the magnitude of the bias in the baseline coefficient estimates. The results suggest that the addition of teacher certification programs that may be completed within four undergraduate years could increase rates of entry into public school teaching by at least 50% among recent graduates of certain selective colleges. JEL Classification: I20, J45, C2

Identifying Examinees Who Possess Distinct and Reliable Subscores When Added Value is Lacking for the Total Sample

Research has demonstrated that although subdomain information may provide no added value beyond the total score, in some contexts such information is of utility to particular demographic subgroups (Sinharay & Haberman, 2014). However, it is argued that the utility of reporting subscores for an individual should not be based on one’s manifest characteristics (e.g., gender or ethnicity), but rather on individual needs for diagnostic information, which is driven by multidimensionality in subdomain scores. To improve the validity of diagnostic information, this study proposed the use of Mahalanobis Distance and HT indices to assess whether an individual’s data significantly departs from unidimensionality. Those examinees that were found to differ significantly were then assessed separately for subscore added value via Haberman’s (2008) procedure. To this end, simulation analyses were conducted to evaluate Type I error, power, and recovery of subscore added value classifications for various levels of subdomain test lengths, subdomain inter-correlations, and proportions of multidimensionality in the total sample. Results demonstrated that the HT index possessed around 100% power across all conditions, while maintaining Type I error below 5%, which led to nearly perfect recovery of subscore added value classifications. In contrast, the power rates for Mahalanobis Distance were much lower ranging from 13% to 61% with Type I errors maintained at the nominal level of 5%. Although the power rates were below the desired criterion of 80%, the cases identified as aberrant using this method were found to have greater variability between subdomain scores, increased reliability, and lower observed subdomain correlations when compared to the generated data. As a result, outlier cases were found to have subscore added value for nearly 100% of cases across conditions even when the generated multidimensional data did not possess subscore added value. These results were cross-validated using a large-scale high-stakes test in which the Mahalanobis Distance measure was found to identify 6.57% of 8,803 test-takers that possessed subscores with added-value who otherwise would have been masked by the unidimensionality of the total sample. Overall, this study suggests that the Mahalanobis Distance measure shows some promise in identifying examinees with multidimensional score profiles

Observational Constraints on the Oxidation of NO_x in the Upper Troposphere

NO_x (NO_x ≡ NO + NO_2) regulates O_3 and HO_x (HO_x ≡ OH + HO_2) concentrations in the upper troposphere. In the laboratory, it is difficult to measure rates and branching ratios of the chemical reactions affecting NO_x at the low temperatures and pressures characteristic of the upper troposphere, making direct measurements in the atmosphere especially useful. We report quasi-Lagrangian observations of the chemical evolution of an air parcel following a lightning event that results in high NO_x concentrations. These quasi-Lagrangian measurements obtained during the Deep Convective Clouds and Chemistry experiment are used to characterize the daytime rates for conversion of NOx to different peroxy nitrates, the sum of alkyl and multifunctional nitrates, and HNO_3. We infer the following production rate constants [in (cm^3/molecule)/s] at 225 K and 230 hPa: 7.2(±5.7) × 10^(–12) (CH_3O_2NO_2), 5.1(±3.1) × 10^(–13) (HO_2NO_2), 1.3(±0.8) × 10^(–11) (PAN), 7.3(±3.4) × 10^(–12) (PPN), and 6.2(±2.9) × 10^(–12) (HNO_3). The HNO_3 and HO_2NO_2 rates are ∼30–50% lower than currently recommended whereas the other rates are consistent with current recommendations to within ±30%. The analysis indicates that HNO_3 production from the HO_2 and NO reaction (if any) must be accompanied by a slower rate for the reaction of OH with NO_2, keeping the total combined rate for the two processes at the rate reported for HNO_3 production above

International genome-wide meta-analysis identifies new primary biliary cirrhosis risk loci and targetable pathogenic pathways.

Primary biliary cirrhosis (PBC) is a classical autoimmune liver disease for which effective immunomodulatory therapy is lacking. Here we perform meta-analyses of discovery data sets from genome-wide association studies of European subjects (n=2,764 cases and 10,475 controls) followed by validation genotyping in an independent cohort (n=3,716 cases and 4,261 controls). We discover and validate six previously unknown risk loci for PBC (Pcombined<5 × 10(-8)) and used pathway analysis to identify JAK-STAT/IL12/IL27 signalling and cytokine-cytokine pathways, for which relevant therapies exist