Columbia Business School Research

Many state and local governments incentivize new business creation. I analyze local growth policy in a setting where firm entry and expansion choices exhibit local complementarities, creating dynamic misallocation at the aggregate level. Optimal entry subsidies would speed the transition of Rust-belt workers to the South and Mountain West by an extra 10 million people by 2035, raising real incomes by 4%. Actual subsidies substantially worsen misallocation, lowering welfare by 3%, 6 times the size of the subsidies themselves.

We propose a political economy mechanism that explains the presence of fiscal regimes punctuated by crisis periods. Our model focuses on the interaction between successive deficit-biased governments subject to i.i.d. fiscal shocks. We show that the economy transitions between a fiscally responsible regime and a fiscally irresponsible regime, with transitions occurring during crises when fiscal needs are large. Under fiscal responsibility, governments limit their spending to avoid transitioning to fiscal irresponsibility.

We study a fiscal policy model in which the government is present-biased towards public spending. Society chooses a fiscal rule to trade off the benefit of committing the government to not overspend against the benefit of granting it flexibility to react to privately observed shocks to the value of spending. Unlike prior work, we examine rules under limited enforcement: the government has full policy discretion and can only be incentivized to comply with a rule via the use of penalties which are joint and bounded. We show that optimal incentives must be bang-bang.

We consider optimal government debt maturity in a deterministic economy in which the government can issue any arbitrary debt maturity structure and in which bond prices are a function of the government's current and future primary surpluses. The government sequentially chooses policy, taking into account how current choices - which impacts future policy -- feed back into current bond prices. We show that issuing consols constitutes the unique stationary optimal debt portfolio, as it boosts government credibility to future policy and reduces the debtfinancing costs.

Emissions control cannot address the consequences of global warming for weather disasters until decades later. We model regional-level mitigation or adaptation, which reduces disaster risks to capital in the interim. Mitigation depends on belief regarding the adverse consequences of global warming. Pessimism jumps with a disaster and slowly reverts in the absence of arrivals. Mitigation spending by firms is less than first-best because of externalities. We prove that capital taxes to fund public mitigation, which requires collective action, restores first-best.

Population growth has declined markedly in almost all major economies since the 1970s. We argue this trend has important consequences for the process of firm dynamics and aggregate growth. We study a rich semi-endogenous growth model of firm dynamics and show analytically that a decline in population growth reduces creative destruction, increases average firm size and concentration, raises market power and misallocation, and lowers aggregate growth in the long-run.

This paper studies lockdown policy in a dynamic economy without government commitment. Lockdown imposes a cap on labor supply, which improves health prospects at the cost of economic output and consumption. A government would like to commit to the extent of future lockdowns in order to guarantee an economic outlook that supports efficient levels of investment into intermediate inputs. However, such a commitment is not credible, since investments are sunk at the time when the government chooses a lockdown. As a result, lockdown under lack of commitment deviates from the optimal policy.

We provide tools to analyze information design problems subject to constraints. We do so by showing that the techniques in Le Treust and Tomala (2019) extend to the case of multiple inequality and equality constraints. This showcases the power of the results in that paper to analyze problems of information design subject to constraints. We illustrate our results with applications to mechanism design with limited commitment (Doval and Skreta, 2020) and persuasion of a privately informed receiver (Kolotilin et al., 2017).

We show that a rise in the minimum wage accounts for a large decline in earnings inequality in Brazil since 1994. To this end, we combine rich administrative and survey data with an equilibrium model of the Brazilian labor market. Our results imply that the minimum wage has far-reaching spillover effects on wages higher up in the distribution, accounting for one-third of the 25.9 log point fall in the variance of log earnings in Brazil since 1994. At the same time, the minimum wage's effects on employment and output are muted by reallocation of workers toward more productive firms.

Compared with existing payment systems, Bitcoin’s throughput is low. Designed to address Bitcoin’s scalability challenge, the Lightning Network (LN) is a protocol allowing two parties to secure bitcoin payments and escrow holdings between them. In a lightning channel, each party commits collateral towards future payments to the counterparty and payments are cryptographically secured updates of collaterals. The network of channels increases transaction speed and reduces blockchain congestion.

How much capital should financial intermediaries hold? We propose a general equilibrium model with a financial sector that makes risky long-term loans to firms, funded by deposits from savers. Government guarantees create a role for bank capital regulation. The model captures the sharp and persistent drop in macro-economic aggregates and credit provision as well as the sharp change in credit spreads observed during the Great Recession.

We estimated the effects of information avoidance and information seeking among parents of children diagnosed with ASD on age of diagnosis. An online survey was completed by 1,815 parents of children with ASD. Children of parents who self-reported that they had preferred "not to know," reported diagnoses around 3 months later than other children.