A\u27s from Zzzz\u27s? The Causal Effect of School Start Time on the Academic Achievement of Adolescents

Recent sleep research finds that many adolescents are sleep-deprived because of both early school start times and changing sleep patterns during the teen years. This study identifies the causal effect of school start time on academic achievement by using two policy changes in the daily schedule at the US Air Force Academy along with the randomized placement of freshman students to courses and instructors. Results show that starting the school day 50 minutes later has a significant positive effect on student achievement, which is roughly equivalent to raising teacher quality by one standard deviation. (JEL I23, J13

Does Professor Quality Matter? Evidence from Random Assignment of Students to Professors

It is difficult to measure teaching quality at the postsecondary level because students typically "self-select" their coursework and their professors. Despite this, student evaluations of professors are widely used in faculty promotion and tenure decisions. We exploit the random assignment of college students to professors in a large body of required coursework to examine how professor quality affects student achievement. Introductory course professors significantly affect student achievement in contemporaneous and follow-on related courses, but the effects are quite heterogeneous across subjects. Students of professors who as a group perform well in the initial mathematics course perform significantly worse in follow-on related math, science, and engineering courses. We find that the academic rank, teaching experience, and terminal degree status of mathematics and science professors are negatively correlated with contemporaneous student achievement, but positively related to follow-on course achievement. Across all subjects, student evaluations of professors are positive predictors of contemporaneous course achievement, but are poor predictors of follow-on course achievement.

Externalities in the Classroom: How Children Exposed to Domestic Violence Affect Everyone’s Kids

There is widespread perception that externalities from troubled children are significant, though measuring them is difficult due to data and methodological limitations. We estimate the negative spillovers caused by children from troubled families by exploiting a unique data set in which children’s school records are matched to domestic violence cases. We find that children from troubled families significantly decrease their peers’ reading and math test scores and increase misbehavior in the classroom. The achievement spillovers are robust to within-family differences and when controlling for school-by-year effects, providing strong evidence that neither selection nor common shocks are driving the results

Externalities in the Classroom: How Children Exposed to Domestic Violence Affect Everyone's Kids

It is estimated that between ten and twenty percent of children in the United States are exposed to domestic violence annually. While much is known about the impact of domestic violence and other family problems on children within the home, little is known regarding the extent to which these problems spill over to children outside the family. The widespread perception among parents and school officials is that these externalities are significant, though measuring them is difficult due to data and methodological limitations. We estimate the negative spillovers caused by children from troubled families by exploiting a unique data set in which children's school records are matched to domestic violence cases filed by their parent. To overcome selection bias, we identify the effects using the idiosyncratic variation in peers from troubled families within the same school and grade over time. We find that children from troubled families significantly decrease their peers' reading and math test scores and significantly increase misbehavior of others in the classroom. The effects are heterogeneous across income, race, and gender and appear to work primarily through troubled boys. The results are robust to within-sibling differences and we find no evidence that non-random selection is driving the results.

Does Drinking Impair College Performance? Evidence from a Regression Discontinuity Approach

This paper examines the effect of alcohol consumption on student achievement. To do so, we exploit the discontinuity in drinking at age 21 at a college in which the minimum legal drinking age is strictly enforced. We find that drinking causes significant reductions in academic performance, particularly for the highest-performing students. This suggests that the negative consequences of alcohol consumption extend beyond the narrow segment of the population at risk of more severe, low-frequency, outcomes.

Does Your Cohort Matter? Measuring Peer Effects in College Achievement

To estimate peer effects in college achievement we exploit a unique dataset in which individuals have been exogenously assigned to peer groups of about 30 students with whom they are required to spend the majority of their time interacting. This feature enables us to estimate peer effects that are more comparable to changing the entire cohort of peers. Using this broad peer group, we find academic peer effects of much larger magnitude than found in previous studies that have measured peer effects among roommates alone. We find the peer effects persist at a diminishing rate into the sophomore, junior, and senior years, indicating social network peer effects may have long lasting effects on academic achievement. Our findings also suggest that peer effects may be working through study partnerships versus operating through establishment of a social norm of effort.

The Long-Run Effects of Disruptive Peers

MacroeconomicsThere's a great deal of research on how classmates can affect test scores and discipline in school, but what about later in life? In Working Paper 1605, PERC's Rex Grey Professor of Economics Mark Hoekstra, Scott E. Carrell of UC Davis, and Elira Kuka of Southern Methodist University, look at the long-term impact of childhood peers, particularly with respect to labor market outcomes in adulthood

Military Retention Incentives: Evidence from the Air Force Selective Reenlistment Bonus

The limited lateral entry and rigid pay structure for U.S. military personnel present challenges in retaining skilled individuals who have attractive options in the civilian labor market. One tool the services use to address this challenge is the Selective Reenlistment Bonus (SRB), which offers eligible personnel with particular skills a substantial cash bonus upon reenlistment. However, the sequential nature of the bonus offer and reenlistment process limits the ability to adjust manpower quickly, raising interest in research that estimates the effect of the SRB on retention. While this literature has acknowledged challenges including potential endogeneity of bonus levels, attrition, and reenlistment eligibility, many studies do not address these concerns adequately. This paper uses a comprehensive panel data set on Air Force enlisted personnel to estimate the effect of the SRB on retention rates. We exploit variation in bonus levels within skill groups, control for civilian labor market conditions, and model reenlistment eligibility to avoid common assumptions that lead to biased impact estimates. We find substantial heterogeneity in the effect of the bonus, with the largest effects on first-term service members and those whose skills have not historically received a substantial bonus. We also find evidence that the bonus affects the timing of reenlistment decisions in addition to their frequency

Assessment of the Red Cell Proteome of Young Patients with Unexplained Hemolytic Anemia by Two-Dimensional Differential In-Gel Electrophoresis (DIGE)

Erythrocyte cytosolic protein expression profiles of children with unexplained hemolytic anemia were compared with profiles of close relatives and controls by two-dimensional differential in-gel electrophoresis (2D-DIGE). The severity of anemia in the patients varied from compensated (i.e., no medical intervention required) to chronic transfusion dependence. Common characteristics of all patients included chronic elevation of reticulocyte count and a negative workup for anemia focusing on hemoglobinopathies, morphologic abnormalities that would suggest a membrane defect, immune-mediated red cell destruction, and evaluation of the most common red cell enzyme defects, glucose-6-phosphate dehydrogenase and pyruvate kinase deficiency. Based upon this initial workup and presentation during infancy or early childhood, four patients classified as hereditary nonspherocytic hemolytic anemia (HNSHA) of unknown etiology were selected for proteomic analysis. DIGE analysis of red cell cytosolic proteins clearly discriminated each anemic patient from both familial and unrelated controls, revealing both patient-specific and shared patterns of differential protein expression. Changes in expression pattern shared among the four patients were identified in several protein classes including chaperons, cytoskeletal and proteasome proteins. Elevated expression in patient samples of some proteins correlated with high reticulocyte count, likely identifying a subset of proteins that are normally lost during erythroid maturation, including proteins involved in mitochondrial metabolism and protein synthesis. Proteins identified with patient-specific decreased expression included components of the glutathione synthetic pathway, antioxidant pathways, and proteins involved in signal transduction and nucleotide metabolism. Among the more than 200 proteins identified in this study are 21 proteins not previously described as part of the erythrocyte proteome. These results demonstrate the feasibility of applying a global proteomic approach to aid characterization of red cells from patients with hereditary anemia of unknown cause, including the identification of differentially expressed proteins as potential candidates with a role in disease pathogenesis