Steven F. Lehrer

Do Peers Affect Student Achievement in China's Secondary Schools?

Peer effects have figured prominently in debates on school vouchers, desegregation, ability tracking, and antipoverty programs. Compelling evidence of their existence remains scarce for plaguing endogeneity issues such as selection bias and the reflection problem. This paper is among the first to firmly establish the link between peer performance and student achievement, using a unique data set from China. We find strong evidence that peer effects exist and operate in a positive and nonlinear manner; reducing the variation of peer performance increases achievement; and our semiparametric estimates clarify the trade-offs facing policymakers in exploiting positive peer effects to increase future achievement.

The impact of poor health on academic performance: New evidence using genetic markers

This paper examines the influence of health conditions on academic performance during adolescence. To account for the endogeneity of health outcomes and their interactions with risky behaviors we exploit natural variation within a set of genetic markers across individuals. We present evidence that specific genetic markers have good statistical properties to identify the impacts of ADHD, depression and obesity. These markers help reveal a new dynamism from poor health to lower academic achievement with substantial heterogeneity in their impacts across genders. Our investigation further exposes the considerable challenges in identifying health impacts due to the prevalence of comorbid health conditions, with clear implications for the health economics literature.

Bargaining in Legislatures: An Experimental Investigation of Open versus Closed Amendment Rules

We investigate the differential effects of open versus closed amendment rules within the framework of a distributive model of legislative bargaining. The data show that there are longer delays in distributing benefits and a more egalitarian distribution of benefits under the open amendment rule, the proposer gets a larger share of the benefits than coalition members under both rules, and play converges toward minimal winning coalitions under the closed amendment rule. However, there are important quantitative differences between the theoretical model underlying the experiment (Baron and Ferejohn 1989) and data, as the frequency of minimal winning coalitions is much greater under the closed rule (the theory predicts minimal winning coalitions under both rules for our parameter values) and the distribution of benefits between coalition members is much more egalitarian than predicted. The latter are consistent with findings from shrinking pie bilateral bargaining game experiments in economics, to which we relate our results.Research support from the Economics Division and the DRMS Divisions of NSF and the University of Pittsburgh is gratefully acknowledged. We have benefited from comments by David Cooper, Massimo Morelli, Jack Ochs, and seminar participants at Carnegie Mellon University, École des Hautes Études Commerciales, Harvard University, Indiana University, ITAM, Université de Montreal, Universite du Québec a Montréal, University of Pittsburgh, Joseph L. Rotman School, University of Toronto, Ohio State University, Texas \widehat{{\rm A}{\&}{\rm M}} University, Tilburg University CENTER, Western Michigan University, The Wharton School, University of Pennsylvania, the 2000 Public Choice Meetings, the 2000 Summer Institute in Behavioral Economics, the 2000 Econometric Society World Congress meetings, and the CEA 35th Annual Meetings. We are responsible for all remaining errors.

Genetic Lotteries within Families

Drawing on findings from the biomedical literature, this paper introduces the idea that specific exogenously inherited differences in the genetic code between full biological siblings can be used to test within-family estimators and potentially improve our understanding of economic relationships. These points are illustrated with an application to identify the causal impact of several poor health conditions on academic outcomes. We present evidence that family fixed effects estimators by themselves cannot fully account for the endogeneity of poor health when estimating education production functions. Further, our analysis elucidates the situations under which genetic markers can serve as instrumental variables for specific health conditions.

Cohort of birth modifies the association between FTO genotype and BMI

Significance Our finding of a significant gene-by-birth-cohort interaction adds a previously unidentified dimension to gene-by-environment interaction research, suggesting that global changes in the environment over time can modify the penetrance of genetic risk factors for diverse phenotypes. This result also suggests that presence (or absence) of a genotype–phenotype correlation may depend on the period of time study subjects were born in, or the historical moment researchers conduct their investigations. A substantial body of research has explored the relative roles of genetic and environmental factors on phenotype expression in humans. Recent research has also sought to identify gene–environment (or g-by-e) interactions, with mixed success. One potential reason for these mixed results may relate to the fact that genetic effects might be modified by changes in the environment over time. For example, the noted rise of obesity in the United States in the latter part of the 20th century might reflect an interaction between genetic variation and changing environmental conditions that together affect the penetrance of genetic influences. To evaluate this hypothesis, we use longitudinal data from the Framingham Heart Study collected over 30 y from a geographically relatively localized sample to test whether the well-documented association between the rs993609 variant of the FTO (fat mass and obesity associated) gene and body mass index (BMI) varies across birth cohorts, time period, and the lifecycle. Such cohort and period effects integrate many potential environmental factors, and this gene-by-environment analysis examines interactions with both time-varying contemporaneous and historical environmental influences. Using constrained linear age–period–cohort models that include family controls, we find that there is a robust relationship between birth cohort and the genotype–phenotype correlation between the FTO risk allele and BMI, with an observed inflection point for those born after 1942. These results suggest genetic influences on complex traits like obesity can vary over time, presumably because of global environmental changes that modify allelic penetrance.

Estimating Treatment Effects from Contaminated Multi-Period Education Experiments: The Dynamic Impacts of Class Size Reductions

This paper introduces an empirical strategy to estimate dynamic treatment effects in randomized trials that provide treatment in multiple stages and in which various noncompliance problems arise, such as attrition and selective transitions between treatment and control groups. Our approach is applied to the highly influential four-year randomized class size study, Project STAR. We find benefits from attending small classes in all cognitive subject areas in kindergarten and first grade. We do not find any statistically significant dynamic benefits from continuous treatment versus never attending small classes following grade 1. Finally, statistical tests support accounting for both selective attrition and noncompliance with treatment assignment.

The Effects of Adolescent Health on Educational Outcomes: Causal Evidence Using Genetic Lotteries between Siblings

There has been growing interest in using specific genetic markers as instrumental variables in attempts to assess causal relationships between health status and socioeconomic outcomes, including human capital accumulation. In this paper, we use a combination of family fixed effects and genetic marker instruments to estimate the causal effects of poor adolescent mental and physical health status on years of completed schooling. By exploiting the genetic variation in inheritance within families, this empirical strategy presents a unique opportunity to isolate the variation in genetic factors from other dynastic and family characteristics. We present evidence that inattentive symptoms in early childhood have large lasting effects in reducing completed schooling. We also find little consistent evidence that adolescent overweight status influences years of schooling completed.

Experimental estimates of the impacts of class size on test scores: robustness and heterogeneity

Proponents of class size reductions (CSRs) draw heavily on the results from Project Student/Teacher Achievement Ratio to support their initiatives. Adding to the political appeal of these initiative are reports that minority and economically disadvantaged students received the largest benefits from smaller classes. We extend this research in two directions. First, to address correlated outcomes from the same class size treatment, we account for the over-rejection of the Null hypotheses by using multiple inference procedures. Second, we conduct a more detailed examination of the heterogeneous impacts of CSRs on measures of cognitive and non-cognitive achievement using more flexible models. We find that students with higher test scores received greater benefits from CSRs. Furthermore, we present evidence that the main effects of the small class treatment are robust to corrections for the multiple hypotheses being tested. However, these same corrections lead the differential impacts of smaller classes by race and free-lunch status to become statistically insignificant.

A genetic instrumental variables analysis of the effects of prenatal smoking on birth weight: evidence from two samples.

There is a large literature showing the detrimental effects of prenatal smoking on birth and childhood health outcomes. It is somewhat unclear, though, whether these effects are causal or reflect other characteristics and choices by mothers who choose to smoke that may also affect child health outcomes or biased reporting of smoking. In this paper, we use genetic markers that predict smoking behaviors as instruments to address the endogeneity of smoking choices in the production of birth and childhood health outcomes. Our results indicate that prenatal smoking produces more dramatic declines in birth weight than estimates that ignore the endogeneity of prenatal smoking, which is consistent with previous studies with non-genetic instruments. We use data from two distinct samples from Norway and the United States with different measured instruments and find nearly identical results. The study provides a novel application that can be extended to study several behavioral impacts on health and social and economic outcomes.

New Evidence on the Impacts of Access to and Attending Universal Child-Care in Canada

Au Canada, les défenseurs des programmes universels de garde d’enfants présentent souvent l’exemple du Québec comme un modèle que les autres provinces devraient suivre en matière de petite enfance et de garde d’enfants. Alors que ces programmes sont très populaires auprès des citoyens, des études portant sur l’accès à ces services ont indiqué qu’ils ont entraîné une multitude d’effets indésirables sur le développement et la santé des enfants ainsi que sur les familles; ces recherches ont évidemment subi beaucoup de critiques et suscité la controverse. Dans cet article, nous montrons que leurs analyses étaient toutefois robustes en ce qui a trait aux questions portant : 1. sur la possibilité que les effets négatifs diminueraient au fur et à mesure que les prestataires de services auraient plus d’expérience ; 2. sur des comparaisons multiples ; et 3. sur le fait que leurs estimations mesuraient l’impact causal de la disponibilité de services de garde et non celui de l’utilisation de ces services. Il y a cependant une exception notable : alors que les estimations des effets des politiques indiquaient une baisse des résultats aux tests de développement moteur et social des enfants au Québec comparativement au reste du Canada, nos analyses impliquent qu’une présence moyenne en service de garde entraîne une hausse significative des résultats à ces tests. Toutefois, nos analyses révèlent une hétérogénéité importante dans les effets des programmes et indiquent que les impacts négatifs rapportés dans les premières recherches sont associés à des enfants qui ont profité d’un service de garde seulement parce que ces services avaient été mis en place.