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

American Apartheid: Segregation and the Making of the Underclass. Douglas S. Massey , Nancy A. Denton

Extending McCallum's (1995) result, based on a gravity model of 1988 trade flows, that a typical Canadian province trades 22 times more with other provinces than with US states of similar size and distance, this paper asks how Quebec trade patterns compare with those of other provinces The results, based on revised data for 1988, 1989 and 1990, show that while the typical province trades more than 20 times as much with other provinces as with comparable US states, for Quebec the multiple is even greater Thus trade between Quebec and the United States appears to be an even less viable alternative to interprovincial trade for Quebec than it is for the rest of Canada The implications of these results for international economics are considerable, as they show that trade linkages within a national economy are far greater than previously imagined If these results are confirmed, they imply that the fabric of national economies is far tighter than that of the global trading system, even for countries operating without substantial trade barriers

Do National Borders Matter for Quebec's Trade?

Many studies use shift-share (or ``Bartik'') instruments, which average a set of shocks with exposure share weights. We provide a new econometric framework for shift-share instrumental variable (SSIV) regressions in which identification follows from the quasi-random assignment of shocks, while exposure shares are allowed to be endogenous. The framework is motivated by an equivalence result: the orthogonality between a shift-share instrument and an unobserved residual can be represented as the orthogonality between the underlying shocks and a shock-level unobservable. SSIV regression coefficients can similarly be obtained from an equivalent shock-level regression, motivating shock-level conditions for their consistency. We discuss and illustrate several practical insights of this framework in the setting of Autor et al. (2013), estimating the effect of Chinese import competition on manufacturing employment across U.S. commuting zones.

Quasi-Experimental Shift-Share Research Designs

This text aims to provide a survey of the state of knowledge in the broad area that includes the theories and facts of economic growth and economic fluctuations, as well as the consequences of monetary and fiscal policies for general economic conditions.

Handbook of macroeconomics

We study inference in shift-share regression designs, such as when a regional outcome is regressed on a weighted average of sectoral shocks, using regional sector shares as weights. We conduct a placebo exercise in which we estimate the effect of a shift-share regressor constructed with randomly generated sectoral shocks on actual labor market outcomes across U.S. Commuting Zones. Tests based on commonly used standard errors with 5\% nominal significance level reject the null of no effect in up to 55\% of the placebo samples. We use a stylized economic model to show that this overrejection problem arises because regression residuals are correlated across regions with similar sectoral shares, independently of their geographic location. We derive novel inference methods that are valid under arbitrary cross-regional correlation in the regression residuals. We show using popular applications of shift-share designs that our methods may lead to substantially wider confidence intervals in practice.

Shift-Share Designs: Theory and Inference

Housing dynamics: An urban approach

We study inference in shift-share regression designs, such as when a regional outcome is regressed on a weighted average of sectoral shocks, using regional sector shares as weights. We conduct a placebo exercise in which we estimate the effect of a shift-share regressor constructed with randomly generated sectoral shocks on actual labor market outcomes across U.S. commuting zones. Tests based on commonly used standard errors with 5% nominal significance level reject the null of no effect in up to 55% of the placebo samples. We use a stylized economic model to show that this overrejection problem arises because regression residuals are correlated across regions with similar sectoral shares, independent of their geographic location. We derive novel inference methods that are valid under arbitrary cross-regional correlation in the regression residuals. We show using popular applications of shift-share designs that our methods may lead to substantially wider confidence intervals in practice.

/pdf/shift-share-designs-theory-and-inference-2g1bfvxfeq.pdf

En este articulo utilizamos variacion geografica plausiblemente exogena en la reduccion de la demanda interna causada por la Gran Recesion en Espana para documentar la existencia de una robusta relacion causal negativa a nivel de empresa entre cambios provocados por la demanda en las ventas internas y en los flujos de exportaciones. Las empresas manufactureras espanolas cuyas ventas internas se redujeron en mayor medida durante la crisis experimentaron un mayor incremento en sus flujos de exportacion, incluso una vez que se controla por sus determinantes de oferta, tales como sus costes laborales. Esta relacion negativa entre cambios en las ventas internas y cambios en los flujos de exportacion provocados por cambios de la demanda ilustra la capacidad de los mercados de exportacion para compensar el impacto negativo de shocks de demanda locales. Los resultados presentados en el articulo se racionalizan a traves de un modelo estandar de exportaciones con heterogeneidad de empresas que permite la existencia de costes marginales de produccion no constantes. Utilizando una version de este modelo estimada de manera estructural, concluimos que las respuestas a nivel de empresa a la caida de la demanda interna en Espana podrian explicar alrededor de la mitad del espectacular incremento de las exportaciones de bienes en Espana (el denominado «milagro exportador espanol») en el periodo 2009-2013.

/pdf/venting-out-exports-during-a-domestic-slump-4j6t3w5k8v.pdf

Eduardo Morales

Papers

Shift-Share Designs: Theory and Inference

Housing dynamics: An urban approach

Shift-Share Designs: Theory and Inference

Shift-Share Designs: Theory and Inference

Venting out : exports during a domestic slump