We investigate conditions sufficient for identification of average treatment effects using instrumental variables. First we show that the existence of valid instruments is not sufficient to identify any meaningful average treatment effect. We then establish that the combination of an instrument and a condition on the relation between the instrument and the participation status is sufficient for identification of a local average treatment effect for those who can be induced to change their participation status by changing the value of the instrument. Finally we derive the probability limit of the standard IV estimator under these conditions. It is seen to be a weighted average of local average treatment effects.

Evolution and Rationality Some Recent Game-Theoretic Results. Identification and Estimation of Local Average Treatment Effects

A common approach to evaluating robustness to omitted variable bias is to observe coefficient movements after inclusion of controls. This is informative only if selection on observables is informative about selection on unobservables. Although this link is known in theory in existing literature, very few empirical articles approach this formally. I develop an extension of the theory that connects bias explicitly to coefficient stability. I show that it is necessary to take into account coefficient and R-squared movements. I develop a formal bounding argument. I show two validation exercises and discuss application to the economics literature. Supplementary materials for this article are available online.

/pdf/unobservable-selection-and-coefficient-stability-theory-and-1r9lpwnnl2.pdf

Unobservable Selection and Coefficient Stability: Theory and Evidence

Resource misallocation can lower aggregate total factor productivity (TFP).We
use microdata on manufacturing establishments to quantify the potential extent
of misallocation in China and India versus the United States. We measure sizable
gaps in marginal products of labor and capital across plants within narrowly
defined industries in China and India compared with the United States. When
capital and labor are hypothetically reallocated to equalize marginal products to
the extent observed in the United States, we calculate manufacturing TFP gains
of 30%–50% in China and 40%–60% in India.

/pdf/misallocation-and-manufacturing-tfp-in-china-and-india-2iv0rc70q7.pdf

Misallocation and Manufacturing TFP in China and India

Econometric policy evaluation: A critique

Artificial intelligence (AI) is increasingly reshaping service by performing various tasks, constituting a major source of innovation, yet threatening human jobs We develop a theory of AI job repl

https://journals.sagepub.com/doi/pdf/10.1177/1094670517752459

Artificial Intelligence in Service

How do movements in the distribution of income and wealth affect the macroeconomy? We create two economies where the only difference between them lies in the initial distribution of economic resources and the degree of frictions in financial markets. Generally, these economies eventually reach the same (or very similar) stationary equilibria in terms of aggregate variables--e.g. capital stock and output. In this sense, financial frictions and wealth distribution have little macroeconomic impact on the stationary equilibria. Here we map out the entire transition dynamics and answer the following questions: (i) Do financial frictions slow down the economy's progression toward the stationary equilibria? (ii) Does inequality affect the speed of convergence to the stationary equilibria? and (iii) If economic resources are initially misallocated (e.g. entrepreneurs not having any resources), is the speed of convergence to the stationary equilibria significantly lower? We find that financial frictions and initial wealth distribution have significant and persistent effects on the transitional dynamics of the aggregate variables

Financial Frictions and the Persistence of History

We study a model with heterogeneous producers that face collateral and cash in advance constraints. These two frictions give rise to a non-trivial financial market in a monetary economy. A tightening of the collateral constraint results in a credit-crunch generated recession. The model can suitable be used to study the effects on the main macroeconomic variables - and on welfare of each individual - of alternative monetary - and fiscal - policies following the credit crunch. The model reproduces several features of the recent financial crisis, like the persistent negative real interest rates, the prolonged period at the zero bound for the nominal interest rate, the collapse in investment and low inflation, in spite of the very large increases of liquidity adopted by the government. The policy implications are in sharp contrast with the prevalent view in most Central Banks, based on the New Keynesian explanation of the liquidity trap.

/pdf/liquidity-traps-and-monetary-policy-managing-a-credit-crunch-3y3vge6foc.pdf

Liquidity Traps and Monetary Policy: Managing a Credit Crunch

We document for a broad panel of advanced economies that increases in GDP per capita are associated with a shift in the composition of value added to sectors that are intensive in high-skill labor. It follows that further development in these economies leads to an increase in the relative demand for skilled labor. We develop a two-sector model of this process and use it to assess the contribution of this process of skill-biased structural change to the rise of the skill premium in the US over the period 1977 to 2005. We find that these compositional demands account for between 25 and 30% of the overall increase of the skill premium due to technical change.

/pdf/skill-biased-structural-change-sey9ffmvbw.pdf

Skill-Biased Structural Change

What are the effects of a temporary lockdown of the economy? Do firms' deteriorating balance sheets and labor market frictions propagate and prolong the effects? We answer these questions in a model with financial and labor market frictions. The model makes quantitative predictions about the effect of lockdowns of varying magnitude and duration on output, employment and firm dynamics. We find that the effects are not persistent if (i) workers on temporary layoff can be recalled by their previous employers without having to go through the frictional labor market and (ii) the government provides employment subsidies to firms during the lockdown. However, the effects are heterogeneous and young non-essential firms are disproportionately affected. In addition, if lockdowns lead to more permanent reallocation across industries, the recession becomes more protracted. Although the paper is motivated by the lockdowns during the Covid-19 pandemic, the framework can be readily applied to large, temporary shocks of different nature.

/pdf/the-economic-ripple-effects-of-covid-19-3vi8hg5cym.pdf

The Economic Ripple Effects of COVID-19

This paper shows that state contingent debt can be syntethically constructed using non-contingent debt of di¤erent maturities. A main policy implication of this principle is that the complete markets Ramsey allocation can be sustained with non-contingent debt only, by properly managing its maturity structure. The numerical experiments, however, suggest that this policy implication ought to be taken with care. We …nd that the debt positions that sustain the Ramsey allocation are very high (on the order of a few hundred times total GDP for a very simple four state economy) and increasing in the number of states. In addition, they are very sensitive to small variations in the parameters of the model

Francisco J. Buera

Papers

Financial Frictions and the Persistence of History

Liquidity Traps and Monetary Policy: Managing a Credit Crunch

Skill-Biased Structural Change

The Economic Ripple Effects of COVID-19

Optimal Maturity of Governement Debt without state contingent bonds