Working Paper
Finkelstein, Amy, Nathaniel Hendren, and Mark Shepard. Working Paper. “Subsidizing Health Insurance for Low-Income Adults: Evidence from Massachusetts”.Abstract

How much are low-income individuals willing to pay for health insurance, and what are the implications for insurance markets? Using administrative data from Massachusetts' subsidized insurance exchange, we exploit discontinuities in the subsidy schedule to estimate willingness to pay and costs of insurance among low-income adults. As subsidies decline, insurance take-up falls rapidly, dropping about 25% for each $40 increase in monthly enrollee premiums. Marginal enrollees tend to be lower-cost, consistent with adverse selection into insurance. But across the entire distribution we can observe – approximately the bottom 70% of the willingness to pay distribution – enrollee willingness to pay is always less than half of own expected costs. As a result, we estimate that take-up will be highly incomplete even with generous subsidies: if enrollee premiums were 25% of insurers' average costs, at most half of potential enrollees would buy insurance; even premiums subsidized to 10% of average costs would still leave at least 20% uninsured. We suggest an important role for uncompensated care for the uninsured in explaining these findings and explore normative implications.

Paper Executive Summary
Revise and Resubmit, American Economic Review
Hendren, Nathaniel. Working Paper. “Measuring Ex-Ante Welfare in Insurance Markets”.Abstract

Revealed-preference measures of willingness to pay capture the value of insurance only against the risk that remains when choosing insurance. This paper provides a method to analyze the impact of insurance market policies on ex-ante expected utility, including the value of insurance against any risk realized prior to choosing insurance. The method uses market demand and cost curves, combined with an estimate of the difference in marginal utilities between insured and uninsured. I provide conditions under which the difference in marginal utilities can be estimated using market demand and cost curves combined with a measure of risk aversion. Applying the approach to previous literature in health insurance, I estimate a greater value to insurance subsidies and mandates than previous approaches that measure market surplus or “deadweight loss”.

Paper Slides
Chetty, Raj, and Nathaniel Hendren. 2017. “The Impact of Neighborhoods on Intergenerational Mobility II: County-Level Estimates”.Abstract

We estimate the causal effect of each county in the U.S. on children's incomes in adulthood. We first estimate a fixed effects model that is identified by analyzing families who move across counties with children of different ages. We then use these fixed effect estimates to (a) quantify how much places matter for intergenerational mobility, (b) construct forecasts of the causal effect of growing up in each county that can be used to guide families seeking to move to opportunity, and (c) characterize which types of areas produce better outcomes. For children growing up in low-income families, each year of childhood exposure to a one standard deviation (SD) better county increases income in adulthood by 0.5%. Hence, growing up in a one SD better county from birth increases a child's income by approximately 10%. There is substantial local area variation in children's outcomes: for example, growing up in the western suburbs of Chicago (DuPage County) would increase a given child's income by approximately 30% relative to growing up in Cook County. Areas with less concentrated poverty, less income inequality, better schools, a larger share of two-parent families, and lower crime rates tend to produce better outcomes for children in poor families. Boys' outcomes vary more across areas than girls' outcomes, and boys have especially negative outcomes in highly segregated areas. One-fifth of the black-white income gap can be explained by differences in the counties in which black and white children grow up. Areas that generate better outcomes have higher house prices on average, but our approach uncovers many “opportunity bargains” – places that generate good outcomes but are not very expensive.

Paper Slides

Accepted, Quarterly Journal of Economics
Data available at
Video presentation available here.
Note: This paper is a revised version of an earlier draft (Chetty and Hendren, 2015), "The Impacts of Neighborhoods on Intergenerational Mobility: Childhood Exposure Effects and County-Level Estimates"

Chetty, Raj, and Nathaniel Hendren. 2017. “The Impacts of Neighborhoods on Intergenerational Mobility I: Childhood Exposure Effects”.Abstract

We show that the neighborhoods in which children grow up shape their earnings, college attendance rates, and fertility and marriage patterns by studying more than seven million families who move across commuting zones and counties in the U.S. Exploiting variation in the age of children when families move, we find that neighborhoods have significant childhood exposure effects: the outcomes of children whose families move to a better neighborhood – as measured by the outcomes of children already living there – improve linearly in proportion to the amount of time they spend growing up in that area, at a rate of approximately 4% per year of exposure. We distinguish the causal effects of neighborhoods from confounding factors by comparing the outcomes of siblings within families, studying moves triggered by displacement shocks, and exploiting sharp variation in predicted place effects across birth cohorts, genders, and quantiles to implement overidentification tests. The findings show that neighborhoods affect intergenerational mobility primarily through childhood exposure, helping reconcile conflicting results in the prior literature.

Paper Slides

Accepted, Quarterly Journal of Economics
Data available at
Video presentation available here.
Note: This paper is a revised version of an earlier draft (Chetty and Hendren, 2015), "The Impacts of Neighborhoods on Intergenerational Mobility: Childhood Exposure Effects and County-Level Estimates"

Hendren, Nathaniel. 2017. “Efficient Welfare Weights”. NBER Working Paper #20351Abstract

How should we measure economic efficiency? The canonical measure is an unweighted sum of willingnesses to pay. In contrast, this paper provides efficient welfare weights that implement the Kaldor-Hicks tests for efficiency but account for the distortionary cost of taxation. The shape of the income distribution yields bounds on these weights that suggest it is efficient to weight surplus to the poor more than to the rich. Point estimates suggest surplus to the poor should be weighted 1.5-2x more than surplus to the rich. I illustrate how to use these weights to evaluate the efficiency of government policy changes.

Slides Paper

Revise and Resubmit, Journal of Political Economy
(An earlier version circulated under the title "The Inequality Deflator: Interpersonal Comparisons without a Social Welfare Function", available here)

Finkelstein, Amy, Nathaniel Hendren, and Erzo F.P. Luttmer. 2016. “The Value of Medicaid: Interpreting Results from the Oregon Health Insurance Experiment”. NBER Working Paper #21308Abstract

We develop a set of frameworks for valuing Medicaid and apply them to welfare analysis of the Oregon Health Insurance Experiment, a Medicaid expansion for low-income, uninsured adults that occurred via random assignment. We estimate that the value of Medicaid to recipients is roughly between one-third and three-quarters of Medicaid's monetary transfers to the external parties who provide partial implicit insurance for the low-income uninsured. Medicaid provides value to recipients through both its expected transfer of resources and its insurance function of moving resources across states of the world. Across approaches, the insurance value to recipients varies considerably, but the transfer value to recipients is stable and always substantial relative to the insurance value. Whether or not the value of Medicaid to recipients exceeds its net (of monetary transfers to external parties) costs depends on the approach used. 
Paper Appendix

Revise and Resubmit, Journal of Political Economy

Journal Article
Chetty, Raj, David Grusky, Nathaniel Hendren, Maximilian Hell, Robert Manduca, and Jimmy Narang. 2017. “The Fading American Dream: Trends in Absolute Income Mobility Since 1940.” Science. Publisher's VersionAbstract

We estimate rates of “absolute income mobility” – the fraction of children who earn more than their parents – by combining historical data from Census and CPS cross-sections with panel data for recent birth cohorts from de-identified tax records. Our approach overcomes the key data limitation that has hampered research on trends in intergenerational mobility: the lack of large panel datasets linking parents and children. We find that rates of absolute mobility have fallen from approximately 90% for children born in 1940 to 50% for children born in the 1980s. The result that absolute mobility has fallen sharply over the past half century is robust to the choice of price deflator, the definition of income, and accounting for taxes and transfers. In counterfactual simulations, we find that increasing GDP growth rates alone cannot restore absolute mobility to the rates experienced by children born in the 1940s. In contrast, changing the distribution of growth across income groups to the more equal distribution experienced by the 1940 birth cohort would reverse more than 70% of the decline in mobility. These results imply that reviving the “American Dream” of high rates of absolute mobility would require economic growth that is spread more broadly across the income distribution.

Paper Slides Executive Summary

Further data and replication code available at

Hendren, Nathaniel. 2017. “Knowledge of Future Job Loss and Implications for Unemployment Insurance.” American Economic Review 107 (7): 1778-1823. Publisher's VersionAbstract

This paper provides evidence that individuals' knowledge about their potential future job loss prevents the existence of a private market for unemployment insurance (UI). Using information contained in subjective probability elicitations, I show privately-traded UI policies would be too adversely selected to be profitable, at any price. Moreover, in response to learning about future unemployment, individuals decrease consumption and spouses are more likely to enter the labor market. From a normative perspective, this suggests existing estimates miss roughly 35% of the social value of UI because it also partially insures against the risk of learning one might lose their job.
Paper Slides
Chetty, Raj, Nathaniel Hendren, Frina Lin, Jeremy Majerovitz, and Benjamin Scuderi. 2016. “Childhood Environment and Gender Gaps in Adulthood.” American Economic Review Papers and Proceedings.Abstract

We show that differences in childhood environments shape gender gaps in adulthood by documenting three facts using population tax records for children born in the 1980s. First, gender gaps in employment rates, earnings, and college attendance vary substantially across the parental income distribution. Notably, the traditional gender gap in employment rates is reversed for children growing up in poor families: boys in families in the bottom quintile of the income distribution are less likely to work than girls. Second, these gender gaps vary substantially across counties and commuting zones in which children grow up. The degree of variation in outcomes across places is largest for boys growing up in poor, single-parent families. Third, the spatial variation in gender gaps is highly correlated with proxies for neighborhood disadvantage. Low-income boys who grow up in high-poverty, high-minority areas work significantly less than girls. These areas also have higher rates of crime, suggesting that boys growing up in concentrated poverty substitute from formal employment to crime. Together, these findings demonstrate that gender gaps in adulthood have roots in childhood, perhaps because childhood disadvantage is especially harmful for boys.

Chetty, Raj, Nathaniel Hendren, and Lawrence Katz. 2016. “The Effects of Exposure to Better Neighborhoods on Children: New Evidence from the Moving to Opportunity Project.” American Economic Review 106 (4).Abstract

The Moving to Opportunity (MTO) experiment offered randomly selected families living in high-poverty housing projects housing vouchers to move to lower-poverty neighborhoods. We present new evidence on the impacts of MTO on children's long-term outcomes using administrative data from tax returns. We find that moving to a lower-poverty neighborhood significantly improves college attendance rates and earnings for children who were young (below age 13) when their families moved. These children also live in better neighborhoods themselves as adults and are less likely to become single parents. The treatment effects are substantial: children whose families take up an experimental voucher to move to a lower-poverty area when they are less than 13 years old have an annual income that is $3,477 (31%) higher on average relative to a mean of $11,270 in the control group in their mid-twenties. In contrast, the same moves have, if anything, negative long-term impacts on children who are more than 13 years old when their families move, perhaps because of disruption effects. The gains from moving fall with the age when children move, consistent with recent evidence that the duration of exposure to a better environment during childhood is a key determinant of an individual's long-term outcomes. The findings imply that offering families with young children living in high-poverty housing projects vouchers to move to lower-poverty neighborhoods may reduce the intergenerational persistence of poverty and ultimately generate positive returns for taxpayers.

Paper Slides
Hendren, Nathaniel. 2016. “The Policy Elasticity.” Tax Policy and the Economy 30. NBER Working Paper #19177Abstract

This paper illustrates how one can use causal effects of a policy change to measure its welfare impact without decomposing them into income and substitution effects. Often, a single causal effect suffices: the impact on government revenue. Because these responses vary with the policy in question, I term them policy elasticities, to distinguish them from Hicksian and Marshallian elasticities. The model also formally justifies a simple benefit-cost ratio for non-budget neutral policies. Using existing causal estimates, I apply the framework to five policy changes: top income tax rate, EITC generosity, food stamps, job training, and housing vouchers. 

Paper Slides
Chetty, Raj, Nathaniel Hendren, Patrick Kline, Emmanuel Saez, and Nicholas Turner. 2014. “Is the United States Still a Land of Opportunity? Recent Trends in Intergenerational Mobility.” American Economic Review Papers and Proceedings 104 (5).Abstract

We present new evidence on trends in intergenerational mobility in the U.S. using administrative earnings records. We find that percentile rank-based measures of intergenerational mobility have remained extremely stable for the 1971-1993 birth cohorts. For children born between 1971 and 1986, we measure intergenerational mobility based on the correlation between parent and child income percentile ranks. For more recent cohorts, we measure mobility as the correlation between a child’s probability of attending college and her parents’ income rank. We also calculate transition probabilities, such as a child’s chances of reaching the top quintile of the income distribution starting from the bottom quintile. Based on all of these measures, we find that children entering the labor market today have the same chances of moving up in the income distribution (relative to their parents) as children born in the 1970s. However, because inequality has risen, the consequences of the “birth lottery” – the parents to whom a child is born – are larger today than in the past.

Paper Slides
Chetty, Raj, Nathaniel Hendren, Patrick Kline, and Emmanuel Saez. 2014. “Where is the Land of Opportunity: The Geography of Intergenerational Mobility in the United States.” Quarterly Journal of Economics 129 (4): 1553-1623. Publisher's VersionAbstract

We use administrative records on the incomes of more than 40 million children and their parents to describe three features of intergenerational mobility in the United States. First, we characterize the joint distribution of parent and child income at the national level. The conditional expectation of child income given parent income is linear in percentile ranks. On average, a 10 percentile increase in parent income is associated with a 3.4 percentile increase in a child's income. Second, intergenerational mobility varies substantially across areas within the U.S. For example, the probability that a child reaches the top quintile of the national income distribution starting from a family in the bottom quintile is 4.4% in Charlotte but 12.9% in San Jose. Third, we explore the factors correlated with upward mobility. High mobility areas have (1) less residential segregation, (2) less income inequality, (3) better primary schools, (4) greater social capital, and (5) greater family stability. While our descriptive analysis does not identify the causal mechanisms that determine upward mobility, the publicly available statistics on

intergenerational mobility developed here can facilitate research on such mechanisms.

Paper Slides
Hendren, Nathaniel. 2014. “Unraveling versus Unraveling: A Memo on Competitive Equilibriums and Trade in Insurance Markets.” Geneva Risk and Insurance Review 39 (2): 176-183. Publisher's VersionAbstract

Both Akerlof (1970) and Rothschild and Stiglitz (1976) show that insurance markets may “un- ravel”. This memo clarifies the distinction between these two notions of unraveling in the context of a binary loss model of insurance. I show that the two concepts are mutually exclusive occurrences. Moreover, I provide a regularity condition under which the two concepts are exhaustive of the set of possible occurrences in the model. Akerlof unraveling characterizes when there are no gains to trade; Rothschild and Stiglitz unraveling shows that the standard notion of competition (pure strategy Nash equilibrium) is inadequate to describe the workings of insurance markets when there are gains to trade.

Paper Lecture Slides
Gruber, Jonathan, Nathaniel Hendren, and Robert M Townsend. 2014. “The Great Equalizer: Health Care Access and Infant Mortality in Thailand.” American Economic Journal: Applied Economics 6 (1): 91 - 107.Abstract

This paper analyzes Thailand’s 2001 healthcare reform, “30 Baht”. The program increased funding available to hospitals to care for the poor and reduced copays to 30 Baht (~$0.75). Our estimates suggest the supply-side funding of the program increased healthcare utilization, especially amongst the poor. Moreover, we find significant impacts on infant mortality: prior to 30 Baht poorer provinces had significantly higher infant mortality rates than richer provinces. After 30 Baht this correlation evaporates to zero. The results suggest that increased access to healthcare among the poor can significantly reduce their infant mortality rates.

Hendren, Nathaniel. 2013. “Private Information and Insurance Rejections.” Econometrica 81 (5): 1713-1762. Slate ArticleAbstract

Across a wide set of nongroup insurance markets, applicants are rejected based on observable, often high-risk, characteristics. This paper argues that private information, held by the potential applicant pool, explains rejections. I formulate this argument by developing and testing a model in which agents may have private information about their risk. I first derive a new no-trade result that theoretically explains how private in- formation could cause rejections. I then develop a new empirical methodology to test whether this no-trade condition can explain rejections. The methodology uses subjec- tive probability elicitations as noisy measures of agents’ beliefs. I apply this approach to three nongroup markets: long-term care, disability, and life insurance. Consistent with the predictions of the theory, in all three settings I find significant amounts of private information held by those who would be rejected; I find generally more private infor- mation for those who would be rejected relative to those who can purchase insurance, and I show it is enough private information to explain a complete absence of trade for those who would be rejected. The results suggest that private information prevents the existence of large segments of these three major insurance markets.

Paper Underwriting Guidelines Supplemental Appendix Slides
Book Chapter
Hendren, Nathaniel. 2015. “[BOOK REVIEW] Journal of Economic Literature Review for Insurance and Behavioral Economics: Improving Decisions in the Most Misunderstood Industry, by Howard C. Kunreuther, Mark V. Pauly and Stacey McMorrow”. Publisher's VersionAbstract

Nathaniel Hendren of Harvard University reviews "Insurance and Behavioral Economics: Improving Decisions in the Most Misunderstood Industry", by Howard C. Kunreuther, Mark V. Pauly, and Stacey McMorrow. The Econlit abstract of this book begins: "Explores the behavior of individuals at risk, insurance industry decision-makers, and policymakers at the local, state, and federal levels involved in the selling, buying, and regulating of insurance. Discusses an introduction to insurance in practice and theory; anomalies and rumors of anomalies; behavior consistent with benchmark models; real-world complications; why people do or do not demand insurance; demand anomalies; descriptive models of insurance supply; anomalies on the supply side; design principles for insurance; strategies for dealing with insurance-related anomalies; innovations in insurance markets through multiyear contracts; publicly provided social insurance; and a framework for prescriptive recommendations. Kunreuther is James G. Dinan Professor of Decision Sciences and Business and Public Policy in the Wharton School and Co-director of the Wharton Risk Management and Decision Processes Center at the University of Pennsylvania. Pauly is Bendheim Professor in the Department of Health Care Management in the Wharton School at the University of Pennsylvania. McMorrow is a research associate in the Health Policy Center at the Urban Institute."