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ERIC Number: EJ1141194
Record Type: Journal
Publication Date: 2017-Jun
Pages: 33
Abstractor: As Provided
ISSN: ISSN-1076-9986
A Weighting Method for Assessing Between-Site Heterogeneity in Causal Mediation Mechanism
Qin, Xu; Hong, Guanglei
Journal of Educational and Behavioral Statistics, v42 n3 p308-340 Jun 2017
When a multisite randomized trial reveals between-site variation in program impact, methods are needed for further investigating heterogeneous mediation mechanisms across the sites. We conceptualize and identify a joint distribution of site-specific direct and indirect effects under the potential outcomes framework. A method-of-moments procedure incorporating ratio-of-mediator-probability weighting (RMPW) consistently estimates the causal parameters. This strategy conveniently relaxes the assumption of no Treatment × Mediator interaction while greatly simplifying the outcome model specification without invoking strong distributional assumptions. We derive asymptotic standard errors that reflect the sampling variability of the estimated weight. We also offer an easy-to-use R package, "MultisiteMediation," that implements the proposed method. It is freely available at the Comprehensive R Archive Network (
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Publication Type: Journal Articles; Reports - Research
Education Level: N/A
Audience: N/A
Language: English
Sponsor: Institute of Education Sciences (ED)
Authoring Institution: N/A
IES Funded: Yes
Grant or Contract Numbers: R305D120020