External Validity in a Stochastic World
45 Pages Posted: 29 Jul 2016
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External Validity in a Stochastic World
External Validity in a Stochastic World
Date Written: July 2016
Abstract
We examine the generalizability of internally valid estimates of causal effects in a fixed population over time when that population is subject to aggregate shocks. This temporal external validity is shown to depend upon the distribution of the aggregate shocks and the interaction between these shocks and the casual effects. We show that returns to investment in agriculture, small and medium enterprises and human capital differ significantly from year to year. We also show how returns to investments interact with specific aggregate shocks, and estimate the parameters of the distributions of these shocks. We show how to use these estimates to appropriately widen estimated confidence intervals to account for aggregate shocks.
Keywords: returns to investment, heterogeneity, treatment effect
JEL Classification: C93, D14, G21, O12, O16
Suggested Citation: Suggested Citation