Disentangling Sources of Variation in C-Section Rates -- by Stefanie J. Fischer, Shuhei Kaneko, Heather Royer, Corey D. White
Cesarean section rates vary widely across U.S. counties, yet it remains unclear how much of this variation reflects demand-side factors (such as patient risk or preferences) versus supply-side factors (such as physician practices or hospital incentives). We develop a new empirical strategy to isolate the influence of supply-side forces. Exploiting hospital obstetric unit closures from 1989–2019 that reallocate some mothers to counties with different C-section rates, we find that a one–percentage-point increase in the delivery county’s rate raises a mother’s likelihood of a C-section by roughly one point. The results point to a dominant role for provider behavior and local practice no..
NBER > Working PapersThe Race Between Asset Supply and Asset Demand -- by Adrien Auclert, Hannes Malmberg, Matthew Rognlie, Ludwig Straub
We introduce an asset supply-and-demand approach to analyze the trajectory of US aggregate wealth, real interest rates, and fiscal sustainability. Our framework uses micro-founded and easy-to-implement sufficient statistics to quantify how shifts in demographics, inequality, and other forces affect asset market equilibrium. From 1950 to the present, rapid population aging, rising income inequality, increasing foreign demand for US assets, and declining productivity growth all contributed to a surge in asset demand. Asset supply initially fell, then turned around sharply, mainly driven by increases in government debt and the value of capitalized profits. Overall, asset demand won the race, an..
NBER > Working PapersSelling to Yourself: Continuation Funds in Private Equity -- by Rustam Abuzov, Will Gornall, Sophie Shive, Ilya A. Strebulaev, Michael S. Weisbach
Continuation funds (CFs) are private equity structures in which a manager raises a new fund to purchase assets from their existing fund. This structure has surged in popularity, from five funds in 2018 to 130 in 2024. We use a hand-collected sample of 472 CFs to test a model in which heterogeneous preferences drive CFs. Consistent with the model’s predictions, CFs emerge when LPs are more heterogeneous and managers have earned carried interest that they can roll. LPs typically choose to exit rather than invest, with this decision driven by both LP-level frictions and time varying LP liquidity demands.
NBER > Working PapersA Note on Factors Influencing Trust in Government -- by Michael J. Boskin, Alexander Kleiner, Ian T. Whiton
Responses to surveys eliciting evaluations of trust in government, both generally and in specific areas, have varied over time and across countries. Using consistent survey data for 34 OECD countries from 2007-2023, we estimate a model of factors determining levels of trust. We employ a series of econometric techniques of increasing sophistication. The level and growth rate of real income per capita, social spending per capita, the degree of decentralization, and economic freedom all exert positive effects on trust. Inflation, unemployment, and debt per capita negatively affect trust. Additionally, higher levels of human capital and the elderly share of the population negatively affect trust..
NBER > Working PapersLeniency Designs: An Operator’s Manual -- by Paul Goldsmith-Pinkham, Peter Hull, Michal Kolesár
We develop a step-by-step guide to leniency (a.k.a. judge or examiner instrument) designs, drawing on recent econometric literatures. The unbiased jackknife instrumental variables estimator (UJIVE) is purpose-built for leveraging exogenous leniency variation, avoiding subtle biases even in the presence of many decision-makers or controls. We show how UJIVE can also be used to assess key assumptions underlying leniency designs, including quasi-random assignment and average first-stage monotonicity, and to probe the external validity of treatment effect estimates. We further discuss statistical inference, arguing that non-clustered standard errors are often appropriate. A reanalysis of Farre-M..
NBER > Working PapersPortfolio Choice and Settlement Frictions: A Theory of Endogenous Convenience Yields -- by Javier Bianchi, Saki Bigio
We study settlement frictions that arise from the need to finance negative balances through an over-the-counter (OTC) market. We derive a closed-form expression for the endogenous convenience yield and show how it can be incorporated into a canonical portfolio problem. Using this framework, we examine how shifts in settlement frictions affect liquidity premia, the volume of overnight funding, the dispersion of market rates, and optimal portfolio allocations. From a normative perspective, we show that in the competitive equilibrium, investors may either over- or under-invest in liquid assets; moreover, both higher risk aversion and tighter aggregate liquidity increase the likelihood of under-..
NBER > Working PapersStablecoins: A Revolutionary Payment Technology with Financial Risks -- by Rashad Ahmed, James A. Clouse, Fabio Natalucci, Alessandro Rebucci, Geyue Sun
The GENIUS Act, recently signed into law, establishes a dual federal and state regulatory framework for stablecoins, effectively segmenting the USD stablecoin market into GENIUS-compliant stablecoins and those that are not. This paper discusses the use cases and potential benefits of stablecoins in terms of payment system efficiency and costs, as well as their substitutability with money market mutual funds and bank deposits. It then analyzes the financial stability risks associated with both GENIUS-compliant and unregulated stablecoins using empirical analysis and historical case studies. It concludes by discussing the economic implications of the emergence of a large dollar stablecoin ecos..
NBER > Working PapersTaxing Identity -- by Joel Slemrod
Taxation based on identity has a long, often sordid history, and persists to this day, usually with some subtlety. It is a relatively tame cousin of the blatant, violent, and genocidal policies that have targeted people of certain religions, races, and genders for millennia. It is, nevertheless, an issue to be confronted rather than ignored by public finance economists. This is especially true because the concept of identity played a prominent role in the US presidential election of 2024, and is likely to be at least an undercurrent to the policy debates beginning in 2025, including those concerning tax policy. Tax based on identity is difficult, although not impossible, to justify within st..
NBER > Working PapersMiddlemen in Search Equilibrium: A Survey -- by Xun (Grace) Gong, Ziqi Qiao, Randall Wright
This essay surveys the literature on middlemen—i.e., intermediation in exchange—reviewing, extending and consolidating key developments in the field. This is important because intermediated trade is common in reality but absent in standard general equilibrium theory. We focus on research using search theory. In various models, agents may act as middlemen when they are good at search, bargaining, recognizing quality, storing inventories, using credit, etc. The theory applies to markets for goods, inputs or assets. We discuss versions with indivisible or divisible goods, fixed or endogenous participation, stationary and dynamic equilibria, and some implications for efficiency and volatilit..
NBER > Working PapersOur Underappreciated International Reserve System -- by Serkan Arslanalp, Barry Eichengreen, Chima Simpson-Bell
We document some underappreciated aspects of the recent evolution of the international reserve system. These include the growing share of gold in global central bank reserves, the continuing emergence of nontraditional reserve currencies, and the stalling share of renminbi in reserves. These trends are consistent with our findings in our earlier papers. In addition we look to the future, pondering the potential implications of dollar-linked stablecoins, the expansion of the BRICS grouping of countries and their de- dollarization plans, the development of blockchain-based platforms such as Project mBridge for the direct exchange of central bank digital currencies, and questions about the doll..
NBER > Working PapersRating Government Procurement Markets -- by Tatyana Deryugina, Alminas Žaldokas, Anastassia Fedyk, Yuriy Gorodnichenko, James Hodson, Ilona Sologoub
We develop a novel, scalable method for assessing the quality of public procurement systems using standard administrative data. Our approach compares the distribution of procurement opportunities to the distribution of contract awards across firms. We first derive a simple theoretical benchmark that relates the expected distribution of contract value winning firms, measured as a Herfindahl–Hirschman index (HHI), to the distribution of auction values, measured as a respective HHI, and the number of winning firms. Significant deviations of winning firms’ HHI from this benchmark indicate potential governance failures such as corruption or unchecked collusion. Our method requires no subjecti..
NBER > Working PapersThe Impact of Pay Transparency in Job Postings on the Labor Market -- by David Arnold, Simon Quach, Bledi Taska
This paper studies the labor market effects of recent state-level policies that require employers to disclose salary information in job postings. Leveraging a difference-in-differences design, we show that employers increased the fraction of postings with salary information by 30 percentage points. Across three datasets, we find consistent evidence of an increase in wages of 1.3-3.6%. We find no impacts on pay dispersion, employment, the number of postings, or skill and education requirements. Our evidence is consistent with pay transparency increasing competition in the labor market, leading to positive spillovers on incumbent workers and always-posting firms.
NBER > Working PapersOccupations, Human Capital Accumulation and Inequality -- by Andrés Erosa, Luisa Fuster, Gueorgui Kambourov, Richard Rogerson
Two robust empirical facts are that mean wages and cross-sectional wage dispersion both increase over the life cycle. We study how these two changes vary across occupations and document a strong positive correlation: occupations with high mean wage growth over the life cycle also exhibit greater increases in cross-sectional wage dispersion. We develop a novel dynamic Roy model that features both static and dynamic comparative advantage and show that it can account for the variation in life cycle wage distributions across high and low wage occupations. Dynamic comparative advantage reflects individual heterogeneity in occupation specific learning abilities and is the dominant force that shape..
NBER > Working PapersViolent Peers at School: Impacts and Mechanisms -- by Victor Lavy, Assaf Yancu
This paper examines the impact of classroom exposure to peers with a history of violent behavior on academic achievement and the underlying mechanisms. This measure of peer violence departs significantly from earlier studies that measured potential peer violence based on the background characteristics of students. We exploit idiosyncratic treatment variations during the transition from primary to middle school for causal identification. We find that a higher proportion of violent peers negatively affects cognitive performance in tests in various subjects, particularly pronounced in mathematics and English, compared to Hebrew and science. These effects are more pronounced in girls than in boy..
NBER > Working PapersEconomic Development According to Chandler -- by Niklas Engbom, Hannes Malmberg, Tommaso Porzio, Federico Rossi, Todd Schoellman
Chandler (1977) shows that large firms require hierarchies of white-collar workers to coordinate complex production. We document that this insight continues to hold globally today, and we show that low education levels in developing countries limit the supply of white-collar workers and constrain firm size. We extend the occupational choice model of Lucas (1978) to allow entrepreneurs to reorganize their firms by allocating administrative tasks to hired professionals, which brings the firm closer to constant returns to scale. We calibrate the model to be consistent with cross-sectional microdata and validate it using quasi-experimental and experimental evidence on the effects of educational ..
NBER > Working PapersDo Test Scores Misrepresent Test Results? An Item-by-Item Analysis -- by Jesse Bruhn, Michael Gilraine, Jens Ludwig, Sendhil Mullainathan
Much of the data collected in education is effectively thrown away. Students answer individual test questions, but administrators and researchers only see aggregate performance. All the item-level data are lost. Ex ante it is not clear this destroys much useful information, since the aggregate might be a sufficient statistic. Using data from Texas for 5 million students and 1.31 billion student-item responses, we show that in fact aggregation does destroy a great deal of valuable information in education: (1) Even conditional on a summary test measure, there is additional information in the item-level data; (2) This additional information is relevant for the student outcomes that education d..
NBER > Working PapersThe Impact of State Paid Sick Leave Mandates on Medicaid-financed Prescription Medications -- by Sumedha Gupta, Johanna Catherine Maclean, Christopher J. Ruhm, Kosali I. Simon
The United States lacks a federal paid sick leave policy. However, 18 states and the District of Columbia have adopted or announced paid sick leave employer mandates to increase access to this benefit, creating a quasi-experimental setting to study whether paid sick leave affects healthcare use. People enrolled in Medicaid are an important population to study in terms of state paid sick leave policies as the majority of non-disabled enrollees are employed, but frequently work in jobs without paid sick leave. Given enrollees’ lower incomes, losing earnings to receive healthcare may be a significant barrier to care. In this study, we examine the effect of state paid sick leave policies on Me..
NBER > Working PapersBranching Fixed Effects: A Proposal for Communicating Uncertainty -- by Patrick M. Kline
Economists often rely on estimates of linear fixed effects models developed by other teams of researchers. Assessing the uncertainty in these estimates can be challenging. I propose a form of sample splitting for network data that breaks two-way fixed effects estimates into statistically independent branches, each of which provides an unbiased estimate of the parameters of interest. These branches facilitate uncertainty quantification, moment estimation, and shrinkage. Algorithms are developed for efficiently extracting branches from large datasets. I illustrate these techniques using a benchmark dataset from Veneto, Italy that has been widely used to study firm wage effects.
NBER > Working PapersA Cold Stop: Temperature, Unemployment and Joblessness Dynamics -- by Joshua S. Graff Zivin, Anthony Lepinteur, Matthew J. Neidell, Adrian Nieto Castro
We provide new evidence that short-run temperature shocks affect unemployment dynamics. Linking daily weather data with three decades of Current Population Survey microdata, we show that cold, but not hot, temperatures significantly increase unemployment risk. This effect is concentrated in climate-exposed industries and driven by both increased job separations and longer unemployment durations. Separations appear to be driven by a rise in layoffs rather than quits, while the increase in unemployment duration is largely explained by a decline in employer vacancy postings. Taken together, temperature-induced joblessness dynamics are primarily demand-driven, rather than a result of changes in ..
NBER > Working PapersSocial Dynamics of AI Adoption -- by Leonardo Bursztyn, Alex Imas, Rafael Jiménez-Durán, Aaron Leonard, Christopher Roth
Anxiety about falling behind can drive people to embrace emerging technologies with uncertain consequences. We study how social forces shape demand for AI-based learning tools early in the education pipeline. In incentivized experiments with parents—key gatekeepers for children’s AI adoption—we elicit their demand for unrestricted AI tools for teenagers’ education. Parental demand rises with the share of other teenagers using the technology, with social forces increasing willingness to pay for AI by more than 60%. Providing information about potentially adverse effects of unstructured AI use negatively shifts beliefs about the merits of AI, but does not change individual demand. Inst..
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