Research in Progress
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Past Automation and Future A.I.: How Weak Links Tame the Growth Explosion (May 2026)
[ Slides ]Abstract
How much of past economic growth is due to automation, and what does this imply about the effects of A.I. in the coming decades? We perform growth accounting using a task-based model for key sectors in the U.S. economy. Historically, TFP growth is driven primarily by improvements in capital productivity. At the task level, capital productivity has grown approximately 4 percentage points per year faster than labor productivity in the U.S. private business sector, and substantially more in some industries. The main benefit of automation is therefore that we use rapidly-improving machines instead of slowly-improving humans on an increasing share of tasks. Looking to the future, we develop an endogenous growth model in which the production of both goods and ideas is endogenously automated and calibrate the model based on our historical accounting. Automation leads economic growth to accelerate, but the acceleration is remarkably slow because of the prominence of
weak links,
i.e., an elasticity of substitution among tasks substantially less than one. Even when most tasks are automated by rapidly-improving capital, output is constrained by the tasks performed by slowly-improving labor. -
Risky Insurance: Life-Cycle Insurance Portfolio Choice with Incomplete Markets (April 2026)
Abstract
We study consumer demand for savings, life insurance, annuities, and long-term care insurance using novel survey data and a structural life-cycle model. We document that individuals perceive substantial insurance nonpayment risk, and these beliefs predict ownership. Embedding elicited beliefs into an incomplete-markets model alongside additional real-world insurance features, we match empirical patterns of low participation. Relative to a no-insurance benchmark, access to existing imperfect insurance reduces median wealth by 16% and generates a modest 0.6% welfare gain. Eliminating nonpayment risk would substantially increase insurance ownership, yield a further 11% decline in median savings, and generate an additional 1.7% welfare gain.
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Risk Markups (November 2025)
Abstract
We study optimal policy when markups reflect compensation for risk instead of market power. Although markups correctly capture the private cost of risk, they are socially inefficient. This calls for a subsidy, as in the market-power perspective. However, uninsurable risk also leads entrepreneurs to dynamically overaccumulate too large a share of wealth to self-insure. Therefore, an income effect makes relatively impoverished workers oversupply labor. In the long run this effect dominates and it is optimal to tax labor and reduce aggregate output, in sharp contrast to the common wisdom derived from the market-power perspective.
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Identification of Marginal Treatment Effects using Subjective Expectations (September 2026)
Abstract
We develop a nonparametric method that identifies marginal treatment effects (MTEs) using survey data on subjective expectations instead of instruments. Subjective treatment probabilities rank people by their latent propensity to be treated if they forecast treatment the same way. Combined with expected treatment-contingent outcomes, the ranking identifies the full MTE function if those expectations are correct on average. Both results hold under common forms of reporting error. We apply the method to study childbirth and female labor supply in Denmark. Estimated MTEs are roughly constant across ranks of fertility beliefs, so there is little selection into childbirth on unobserved determinants of work after birth. The survey-based average treatment effect on the treated nearly equals the event-study estimate from administrative data at every horizon, evidence that the identifying assumptions hold. Furthermore, eliciting beliefs under a counterfactual policy measures its effect before implementation, accounting for how the policy changes selection into treatment.
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Beliefs and Realities of Work and Childcare After Childbirth (July 2026)
Abstract
When women plan for life after childbirth, they form beliefs about work, childcare, and how their careers will unfold. These expectations shape key decisions but are formed under deep uncertainty. We use a 2019 state-contingent survey of 11,000 Danish women linked to administrative data to compare pre-birth beliefs to realized outcomes. Mothers accurately anticipate their eventual return to work but underestimate the duration of the career interruption. This miscalibration stems from two belief errors—about partner leave and own labor supply—which interact and persist even among second-time mothers, with implications for labor supply, planning, and policy design.
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Due Diligence: Endogenous Information Acquisition and Offer Quality in Search and Matching (August 2026)
Abstract
In many search markets, offers must be accepted or rejected before their quality is known. We build a search and matching model in which suppliers privately choose offer quality and searchers choose costly due diligence before accepting. How carefully searchers screen determines the mix of high- and low-quality offers. This composition channel is absent when information and offer quality are exogenous. In the static model, improving low-quality offers makes accepting one less bad, so searchers screen less carefully and suppliers post more low-quality offers. The mix worsens enough that more searchers remain unmatched and their welfare falls. Raising the value of remaining unmatched actually reduces the number of unmatched searchers, because searchers screen more carefully and suppliers post more high-quality offers. In the dynamic economy the composition channel survives, and a classic market tightness force can reinforce or overturn it. A planner who treats information and offer quality as exogenous can subsidize entry where a tax is optimal.
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The Value of a Job (Work in Progress)
Abstract
We estimate the present discounted value of earnings for a particular worker having a job at a particular firm, using a nonparametric statistical model that nests many rich structural models. We assume a stationary Markov structure conditional on a vector of idiosyncratic states, where states determine payoffs and transitions. We use rich employer-employee matched data from Denmark, cluster workers and firms into types, define a parsimonious set of state variables, and estimate type- and state-specific payoffs and transition probabilities directly from their empirical counterparts. We then compute values by iterating over a Bellman equation. We decompose the value into its components, including earnings on the current job, the probability of staying or moving to a new job of a particular type and the earnings growth associated with staying or moving, and transitions to nonemployment with associated payoffs. We also compare the distribution of job value changes upon job-to-job moves to the wage change distribution and show how patterns of worker and firm sorting differ when using values instead of wages.