Testing the "separability" condition in two-stage nonparametric models of production

Cinzia Daraio, Leopold Simar and Paul Wilson

LEM Papers Series from Laboratory of Economics and Management (LEM), Sant'Anna School of Advanced Studies, Pisa, Italy

Abstract: Simar and Wilson (J. Econometrics, 2007) provided a statistical model that can rationalize two-stage estimation of technical efficiency in nonparametric settings. Two-stage estimation has been widely used, but requires a strong assumption: the second-stage environmental variables cannot affect the support of the input and output variables in the first stage. In this paper, we provide a fully nonparametric test of this assumption. The test relies on new central limit theorem (CLT) results for unconditional efficiency estimators developed by Kneip et al. (Econometric Theory, 2015a) and new CLTs for conditional efficiency estimators developed in this paper. The test can be implemented relying on either asymptotic normality of the test statistics or using bootstrap methods to obtain critical values. Our simulation results indicate that our tests perform well both in terms of size and power. We present a real-world empirical example by updating the analysis performed by Aly et al. (R. E. Stat., 1990) on U.S. commercial banks; our tests easily reject the assumption required for two-stage estimation, calling into question results that appear in hundreds of papers that have been published in recent years.

Keywords: technical efficiency; conditional efficiency; two-stage estimation; bootstrap; separability; data envelopment analysis (DEA); free-disposal hull (FDH). (search for similar items in EconPapers)
Date: 2015
New Economics Papers: this item is included in nep-eff
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Citations: View citations in EconPapers (19)

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Related works:
Working Paper: Testing the "Separability" Condition in Two-Stage Nonparametric Models of Production (2015)
Working Paper: Testing the "Separability" Condition in Two-Stage Nonparametric Models of Production (2015)
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Persistent link: https://EconPapers.repec.org/RePEc:ssa:lemwps:2015/21

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