We show that the two-variable VAR model of Blanchard and Quah (1989) produces results identical to those based on the Sims (1980) orthogonalization if the first-ordered variable is not caused in the long run by the second-ordered variable. Some illustrative examples are provided to demonstrate...

This chapter reviews and synthesizes our current understanding of the shocks that drive economic fluctuations. The chapter begins with an illustration of the problem of identifying macroeconomic shocks, followed by an overview of the many recent innovations for identifying shocks. It then...

We develop a method that identifies the effects of nationwide policy, i.e., policy implemented across all regions at the same time. The core idea is to track outcome paths in terms of stages rather than time, where a stage of a regional outcome at time t is its location on the support of a...

Multivalued treatments are commonplace in applications. We explore the use of discrete-valued instruments to control for selection bias in this setting. Our discussion revolves around the concept of targeting: which instruments target which treatments. It allows us to establish conditions under...

This paper studies semiparametric versions of the classical sample selection model (Heckman (1976, 1979)) without exclusion restrictions. We extend the analysis in Honor'e and Hu (2020) by allowing for parameter heterogeneity and derive implications of this model. We also consider models that...

The Credibility Revolution advances quantitative research designs intended to identify causal effects from observed data. The ensuing emphasis on internal validity however has enabled the neglect of construct and external validity. This article develops a framework we call causal specification....