Identification of causal mechanisms based on between-subject double randomization designs

Conny Wunsch and Renate Strobl

No 13028, CEPR Discussion Papers from C.E.P.R. Discussion Papers

Abstract: Understanding the mechanisms through which treatment effects come about is crucial for designing effective interventions. The identification of such causal mechanisms is challenging and typically requires strong assumptions. This paper discusses identification and estimation of natural direct and indirect effects in so-called double randomization designs that combine two experiments. The first and main experiment randomizes the treatment and measures its effect on the mediator and the outcome of interest. A second auxiliary experiment randomizes the mediator of interest and measures its effect on the outcome. We show that such designs allow for identification based on an assumption that is weaker than the assumption of sequential ignorability that is typically made in the literature. It allows for unobserved confounders that do not cause heterogeneous mediator effects. We demonstrate estimation of direct and indirect effects based on different identification strategies that we compare to our approach using data from a laboratory experiment we conducted in Kenya.

Keywords: Direct and indirect effects; Causal inference; Mediation analysis; Identification (search for similar items in EconPapers)
JEL-codes: C31 (search for similar items in EconPapers)
Date: 2018-07
New Economics Papers: this item is included in nep-ecm and nep-exp
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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Related works:
Working Paper: Identification of causal mechanisms based on between-subject double randomization designs (2018)
Working Paper: Identification of Causal Mechanisms Based on Between-Subject Double Randomization Design (2018)
Working Paper: Identification of Causal Mechanisms Based on Between-Subject Double Randomization Designs (2018)
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