We evaluate the effects of the 2020 student debt moratorium that paused payments for student loan borrowers. Using administrative credit panel data, we show that the payment pause led to a sharp drop in student loan payments and delinquencies for borrowers subject to the debt moratorium, as well as an increase in credit scores. We find a large stimulus effect, as borrowers substitute increased private debt for paused public debt. Comparing borrowers whose loans were frozen with borrowers whose loans were not frozen due to differences in whether the government owned the loans, we show that borrowers used the new liquidity to increase borrowing on credit cards, mortgages, and auto loans rather than avoid delinquencies. The effects are concentrated among borrowers without prior delinquencies, who saw no change in credit scores, and we see little effects following student loan forgiveness announcements. The results highlight an important complementarity between liquidity and credit, as liquidity increases the demand for credit even as the supply of credit is fixed.

Search frictions can explain why the "law of one price" fails in retail markets and why even firms selling commodity products have pricing power. In online commerce, physical search costs are low, yet price dispersion is common. We use browsing data from eBay to estimate a model of consumer search and price competition when retailers offer homogeneous goods. We find that retail margins are on the order of 10%, and use the model to analyze the design of search rankings. Our model explains most of the effects of a major re-design of eBay's product search, and allows us to identify conditions where narrowing consumer choice sets can be pro-competitive. Finally, we examine a subsequent A/B experiment run by eBay that illustrates the greater difficulties in designing search algorithms for differentiated products, where price is only one of the relevant product attributes.

Human capital can depreciate if skills are unused. But estimating human capital depreciation is challenging, as worker skills are difficult to measure and less productive workers are more likely to spend time in non-employment. We overcome these challenges with new administrative data on teachers' assignments and their students' outcomes, and quasi-random variation from the teacher assignment process in Greece. We find significant losses to output, as a one-year increase in time without formal employment lowers students' test scores by 0.05 standard deviations. Using a simple production model, we estimate a skill depreciation rate of 4.3% and experience returns of 6.8%.

We study whether reallocating existing teachers across schools within a district can increase student achievement, and what policies would help achieve these gains. Using a model of multi-dimensional value-added, we find meaningful achievement gains from reallocating teachers within a district. Using an estimated equilibrium model of the teacher labor market, we find that achieving most of these gains requires directly affecting teachers' preferences over schools. In contrast, directly affecting principals' selection of teachers can lower student achievement. Our analysis highlights the importance of equilibrium and second-best reasoning in analyzing teacher labor market policies.

What happens when employers would like to screen their employees but only observe a subset of output? We specify a model in which heterogeneous employees respond by producing more of the observed output at the expense of the unobserved output. Though this substitution distorts output in the short-term, we derive three sufficient conditions under which the heterogenous response improves screening efficiency: 1) all employees place similar value on staying in their current role; 2) the employees' utility functions satisfy a variation of the traditional single-crossing condition; 3) employer and worker preferences over output are similar. We then assess these predictions empirically by studying a change to teacher tenure policy in New York City, which increased the role that a single measure -- test score value-added -- played in tenure decisions. We show that in response to the policy teachers increased test score value-added and decreased output that did not enter the tenure decision. The increase in test score value-added was largest for the teachers with more ability to improve students' untargeted outcomes, increasing their likelihood of getting tenure. We find that the endogenous response to the policy announcement reduced the screening efficiency gap -- defined as the reduction of screening efficiency stemming from the partial observability of output -- by 28%, effectively shifting some of the cost of partial observability from the post-tenure period to the pre-tenure period.

The teacher labor market is a two-sided matching market where the effects of policies depend on the actions of both sides. We specify a matching model of teachers and schools that we estimate with rich data on teachers' applications and principals' ratings. Both teachers' and principals' preferences deviate from those that would maximize the achievement of economically disadvantaged students: teachers prefer schools with fewer disadvantaged students, and principals' ratings are weakly related to teacher effectiveness. In equilibrium, these two deviations combine to produce a surprisingly equitable current allocation where teacher quality is balanced across advantaged and disadvantaged students. To close academic achievement gaps, policies that address deviations on one side alone are ineffective or harmful, while policies that address both deviations could substantially increase disadvantaged students' achievement.

What happens when employers would like to screen their employees but only observe a subset of output? We specify a model in which heterogeneous employees respond by producing more of the observed output at the expense of the unobserved output. Though this substitution distorts output in the short-term, we derive three sufficient conditions under which the heterogenous response improves screening efficiency: 1) all employees place similar value on staying in their current role; 2) the employees' utility functions satisfy a variation of the traditional single-crossing condition; 3) employer and worker preferences over output are similar. We then assess these predictions empirically by studying a change to teacher tenure policy in New York City, which increased the role that a single measure -- test score value-added -- played in tenure decisions. We show that in response to the policy teachers increased test score value-added and decreased output that did not enter the tenure decision. The increase in test score value-added was largest for the teachers with more ability to improve students' untargeted outcomes, increasing their likelihood of getting tenure. We find that the endogenous response to the policy announcement reduced the screening efficiency gap -- defined as the reduction of screening efficiency stemming from the partial observability of output -- by 28%, effectively shifting some of the cost of partial observability from the post-tenure period to the pre-tenure period.

Human capital can depreciate if skills are unused. But estimating human capital depreciation is challenging, as worker skills are difficult to measure and less productive workers are more likely to spend time in non-employment. We overcome these challenges with new administrative data on teachers' assignments and their students' outcomes, and quasi- random variation from the teacher assignment process in Greece. We find significant losses to output, as a one-year increase in time without formal employment lowers students' test scores by 0.09 standard deviations. Using a simple production model, we estimate a skill depreciation rate of 4.3% and experience returns of 6.8%.