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Activity Number:
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483
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Type:
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Topic Contributed
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Date/Time:
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Wednesday, August 3, 2016 : 8:30 AM to 10:20 AM
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Sponsor:
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Survey Research Methods Section
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Abstract #319028
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View Presentation
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Title:
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Analyzing Heterogeneous Causal Mediation Effects in Multi-Site Trials With Application to the National Job Corps Study
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Author(s):
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Xu Qin* and Guanglei Hong
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Companies:
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The University of Chicago and The University of Chicago
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Keywords:
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Direct and indirect effects ;
method of moments ;
multilevel modeling ;
ratio-of-mediator-probability weighting ;
two-step estimation ;
multisite randomized trials
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Abstract:
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When a multi-site 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-by-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.
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Authors who are presenting talks have a * after their name.
