April 2025 - Working Paper33635 Landmark results from the Women's Health Initiative trial showed that random assignment to menopausal hormone therapy (MHT) elevated risks of breast cancer and other adverse events. Recent analyses argue that MHT risks are small. These analyses report intention-to-treat (ITT) effects, ignoring the...
March 2025 - Working Paper33622 School districts increasingly gauge school quality with surveys that ask about school climate and student engagement. We use data from New York Citys middle and high schools to compare the long-run predictive validity of surveys with that of conventional test score value-added models (VAMs). Our...
December 2024 - Working Paper33281 Elite economics PhD programs aim to train graduate students for a lifetime of academic research. This paper asks how advising affects graduate students post-PhD research productivity. Advising is highly concentrated: at the eight highly-selective schools in our study, a minority of advisors do most...
December 2024 - Working Paper33296 The ISCHEMIA Trial randomly assigned patients with ischemic heart disease to an invasive treatment strategy centered on revascularization with a control group assigned non-invasive medical therapy. As is common in such strategy trials, many participants assigned to treatment remained untreated while...
July 2023 - Working Paper31443 Pragmatic cancer screening trials mimic real-world scenarios in which patients and doctors are the ultimate arbiters of treatment. Intention-to-screen (ITS) analyses of such trials maintain randomization-based apples-to-apples comparisons, but differential adherence (the failure of subjects assigned...
December 2022 - Working Paper30803 Many personal and policy decisions turn on perceptions of school effectiveness, defined here as the causal effect of attendance at a particular school or set of schools on student test scores and other outcomes. Widely-disseminated school ratings frameworks compare average student achievement across...
September 1, 2022 - Article
In the 1970s, court orders to integrate schools led many US cities to bus students far from home. Though court-mandated busing has disappeared, many urban districts now have voluntary school choice programs that allow students to attend schools outside of their neighborhoods when space permits. In...
August 2022 - Working Paper30308 School assignment in Boston and New York City came to national attention in the 1970s as courts across the country tried to integrate schools. Today, district-wide choice allows Boston and New York students to enroll far from home, perhaps enhancing integration. Urban school transportation is...
February 2022 - Working Paper29726 The view that empirical strategies in economics should be transparent and credible now goes almost without saying. The local average treatment effects (LATE) framework for causal inference helped make this so. The LATE theorem tells us for whom particular instrumental variables (IV) and regression...
January 2022 - Working Paper29608 In large urban districts, schools enrolling more white students tend to have higher performance ratings. We use an instrumental variables strategy leveraging centralized school assignment to explore this relationship. Estimates from Denver and New York City suggest the correlation between school...
November 2021 - Working Paper29417 We revisit the finite-sample behavior of just-identified instrumental variables (IV) estimators, arguing that in most microeconometric applications, just-identified IV bias is negligible and the usual inference strategies likely reliable. Three widely-cited applications are used to explain why this...
January 4, 2021 - Article
Full scholarships to low-income high school graduates in Nebraska raised college enrollment and completion, especially for those with the least academic preparation and greatest family disadvantage. T he goal of most financial aid programs is to increase educational attainment for prospective...
December 2020 - Working Paper28241 Many large urban school districts match students to schools using algorithms that incorporate an element of random assignment. We introduce two simple empirical strategies to harness this randomization for value-added models (VAMs) measuring the causal effects of individual schools. The first...
September 2020 - Working Paper27834 Financial aid from the Susan Thompson Buffett Foundation (STBF) provides exceptionally generous support to a college population similar to that served by a host of state aid programs. In conjunction with STBF, we randomly assigned aid awards to thousands of Nebraska high school graduates from low...
December 2019 - Working Paper26584 Machine learning (ML) is mostly a predictive enterprise, while the questions of interest to labor economists are mostly causal. In pursuit of causal effects, however, ML may be useful for automated selection of ordinary least squares (OLS) control variables. We illustrate the utility of ML for...
August 2019 - Working Paper26137 The educational mismatch hypothesis asserts that students are hurt by affirmative action policies that place them in selective schools for which they wouldn't otherwise qualify. We evaluate mismatch in Chicago's selective public exam schools, which admit students using neighborhood-based diversity...
January 2018 - Working Paper24172 Many centralized matching schemes incorporate a mix of random lottery and non-lottery tie-breaking. A leading example is the New York City public school district, which uses criteria like test scores and interviews to generate applicant rankings for some schools, combined with lottery tie-breaking...
October 2017 - Working Paper23891 Ride-hailing drivers pay a proportion of their fares to the ride-hailing platform operator, a commission-based compensation model used by many internet-mediated service providers. To Uber drivers, this commission is known as the Uber fee. By contrast, traditional taxi drivers in most US cities make...
September 21, 2017 - Article
Other disciplines increasingly cite economics, and vice versa. This development parallels a rise in the importance of empirical work in economics. Economics is sometimes described as an isolated field that interacts little with other academic disciplines. In...
August 2017 - Working Paper23698 Does academic economic research produce material of scientific value, or are academic economists writing only for clients and peers? Is economics scholarship uniquely insular? We address these questions by quantifying interactions between economics and other disciplines. Changes in the impact of...
June 2017 - Working Paper23486 We use the discontinuous function of enrollment known as Maimonides Rule as an instrument for class size in large Israeli samples from 2002-2011. As in the 1991 data analyzed by Angrist and Lavy (1999), Maimonides Rule still has a strong first stage. In contrast with the earlier Israeli estimates,...
February 2017 - Working Paper23144 The past half-century has seen economic research become increasingly empirical, while the nature of empirical economic research has also changed. In the 1960s and 1970s, an empirical economists typical mission was to explain economic variables like wages or GDP growth. Applied econometrics has since...
January 2017 - Working Paper23015 This paper reports updated findings from a randomized evaluation of a generous, privately-funded scholarship program for Nebraska public college students. Scholarship offers boosted college enrollment and persistence. Four years after award receipt, randomly-selected scholarship winners were 13...
November 2015 - Working Paper21748 Conventional value-added models (VAMs) compare average test scores across schools after regression-adjusting for students demographic characteristics and previous scores. This paper tests for VAM bias using a procedure that asks whether VAM estimates accurately predict the achievement consequences...
November 2015 - Working Paper21705 A growing number of school districts use centralized assignment mechanisms to allocate school seats in a manner that reflects student preferences and school priorities. Many of these assignment schemes use lotteries to ration seats when schools are oversubscribed. The resulting random assignment...
January 2015 - Working Paper20800 Does financial aid increase college attendance and completion? Selection bias and the high implicit tax rates imposed by overlapping aid programs make this question difficult to answer. This paper reports initial findings from a randomized evaluation of a large privately-funded scholarship program...
December 2014 - Working Paper20792 Lottery estimates suggest oversubscribed urban charter schools boost student achievement markedly. But these estimates neednt capture treatment effects for students who havent applied to charter schools or for students attending charters for which demand is weak. This paper reports estimates of the...
May 2014 - Working Paper20173 An instrumental variables (IV) identification strategy that exploits statutory class size caps shows significant achievement gains in smaller classes in Italian primary schools. Gains from small classes are driven mainly by schools in Southern Italy, suggesting a substantial return to class size...
December 2013 - Working Paper19774 Individual outcomes are highly correlated with group average outcomes, a fact often interpreted as a causal peer effect. Without covariates, however, outcome-on-outcome peer effects are vacuous, either unity or, if the average is defined as leave-out, determined by a generic intraclass correlation...
August 2013 - Working Paper19355 We develop a flexible semiparametric time series estimator that is then used to assess the causal effect of monetary policy interventions on macroeconomic aggregates. Our estimator captures the average causal response to discrete policy interventions in a macro-dynamic setting, without the need for...
July 2013 - Working Paper19275 We use admissions lotteries to estimate the effects of attendance at Boston's charter high schools on college preparation, college attendance, and college choice. Charter attendance increases pass rates on the high-stakes exam required for high school graduation in Massachusetts, with especially...
December 2012 - Working Paper18662 In the canonical regression discontinuity (RD) design for applicants who face an award or admissions cutoff, causal effects are nonparametrically identified for those near the cutoff. The impact of treatment on inframarginal applicants is also of interest, but identification of such effects requires...
December 1, 2011 - Article
Over-subscribed urban charter schools that admit students by lottery have produced the largest improvement in student achievement. Comparisons of those who did and did not win charter school admissions lotteries in Massachusetts suggest that urban charter schools boost student achievement. In...
August 2011 - Working Paper17332 Estimates using admissions lotteries suggest that urban charter schools boost student achievement, while charter schools in other settings do not. We explore student-level and school-level explanations for these differences using a large sample of Massachusetts charter schools. Our results show that...
July 2011 - Working Paper17264 Talented students compete fiercely for seats at Boston and New York exam schools. These schools are characterized by high levels of peer achievement and a demanding curriculum tailored to each district's highest achievers. While exam school students do very well in school, the question of whether an...
December 2010 - Working Paper16643 We evaluate the effects of academic achievement awards for first and second-year college students on a Canadian commuter campus. The award scheme offered linear cash incentives for course grades above 70. Awards were paid every term. Program participants also had access to peer advising by...
December 2010 - Working Paper16566 This paper develops a covariate-based approach to the external validity of instrumental variables (IV) estimates. Assuming that differences in observed complier characteristics are what make IV estimates differ from one another and from parameters like the effect of treatment on the treated, we show...
March 2010 - Working Paper15794 This essay reviews progress in empirical economics since Leamer's (1983) critique. Leamer highlighted the benefits of sensitivity analysis, a procedure in which researchers show how their results change with changes in specification or functional form. Sensitivity analysis has had a salutary but not...
February 2010 - Working Paper15740 Charter schools affiliated with the Knowledge is Power Program (KIPP) are emblematic of the No Excuses approach to public education. These schools feature a long school day, an extended school year, selective teacher hiring, strict behavior norms and a focus on traditional reading and math skills....
November 2009 - Working Paper15549 Charter schools are publicly funded but operate outside the regulatory framework and collective bargaining agreements characteristic of traditional public schools. In return for this freedom, charter schools are subject to heightened accountability. This paper estimates the impact of charter school...
June 1, 2009 - Article
The number of Vietnam-era VDC beneficiaries grew rapidly in the late 1990s, growth that accelerated in the early part of this century and has not yet leveled off. The Veterans Disability Compensation Program (VDC), which provides a monthly stipend to disabled veterans, is the third largest American...
March 2009 - Working Paper14781 The veterans disability compensation (VDC) program, which provides a monthly stipend to disabled veterans, is the third largest American disability insurance program. Since the late 1990s, VDC growth has been driven primarily by an increase in claims from Vietnam veterans, raising concerns about...
September 2007 - Working Paper13411 This paper uses the 2000 Census 1-in-6 sample to look at the long-term impact of Vietnam-era military service. Instrumental Variables estimates using draft-lottery instruments show post-service earnings losses close to zero in 2000, in contrast with earlier results showing substantial earnings...
December 2006 - Working Paper12790 High rates of attrition, delayed completion, and poor achievement are growing concerns at colleges and universities in North America. This paper reports on a randomized field experiment involving two strategies designed to improve these outcomes among first-year undergraduates at a large Canadian...
February 2006 - Working Paper12005 Between 1898 and 1948, English was the language of instruction for most post-primary grades in Puerto Rican public schools. Since 1949, the language of instruction in all grades has been Spanish. We use this policy change to estimate the effect of English-intensive instruction on the English...
December 2005 - Working Paper11835 A longstanding question in the economics of the family is the relationship between sibship size and subsequent human capital formation and economic welfare. If there is a "quantity-quality trade-off," then policies that discourage large families should lead to increased human capital, higher...
September 2005 - Working Paper0314 Quantitative criminology focuses on straightforward causal questions that are ideally addressed with randomized experiments. In practice, however, traditional randomized trials are difficult to implement in the untidy world of criminal justice. Even when randomized trials are implemented, not...
March 2005 - Working Paper11219 Natural and agricultural resources for which there is a substantial black market, such as coca, opium, and diamonds, appear especially likely to be exploited by the parties to a civil conflict. On the other hand, these resources may also provide one of the few reliable sources of income in the...
December 2004 - Working Paper10975 Time series data are widely used to explore causal relationships, typically in a regression framework with lagged dependent variables. Regression-based causality tests rely on an array of functional form and distributional assumptions for valid causal inference. This paper develops a semi-parametric...
August 2004 - Working Paper10713 Colombia's PACES program provided over 125,000 poor children with vouchers that covered half the cost of private secondary school. The vouchers were renewable annually conditional on adequate academic progress. Since many vouchers were assigned by lottery, program effects can reliably be assessed by...
