Abstract
This paper describes methodology for analyzing data from cluster randomized trials with count outcomes, taking indirect effects as well spatial effects into account. Indirect effects are modelled using a novel application of a measure of depth within the intervention arm. Both direct and indirect effects can be estimated accurately even when the proposed model is misspecified. We use spatial regression models with Gaussian random effects, where the individual outcomes have distributions overdispersed with respect to the Poisson, and the corresponding direct
and indirect effects have a marginal interpretation. To avoid spatial confounding, we use orthogonal regression, in which random effects represent spatial dependence using a homoscedastic and dimensionally-reduced modification
of the intrinsic conditional autoregression (ICAR) model. We illustrate the methodology using spatial data from a pair-matched cluster randomized trial against the dengue mosquito vector Aedes aegypti, done in Trujillo, Venezuela
and indirect effects have a marginal interpretation. To avoid spatial confounding, we use orthogonal regression, in which random effects represent spatial dependence using a homoscedastic and dimensionally-reduced modification
of the intrinsic conditional autoregression (ICAR) model. We illustrate the methodology using spatial data from a pair-matched cluster randomized trial against the dengue mosquito vector Aedes aegypti, done in Trujillo, Venezuela
Original language | English |
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Pages (from-to) | 490-505 |
Journal | Biometrics |
Volume | 77 |
Issue number | 2 |
Early online date | 18 Jun 2020 |
DOIs | |
Publication status | Published - 1 Jun 2021 |
Bibliographical note
Funding Information:This work was supported by the United Kingdom Medical Research Council (MRC) via Grant Reference G7508177, also by MRC and the UK Department for International Development (DFID), MRC Grant References MR/K012126/1 and MR/R010161/1, awards jointly funded by the MRC and DFID under the MRC/DFID Concordat agreement and also part of the EDCTP2 programme supported by the European Union. We also thank Christian Bottomley for helpful suggestions, Valeria Simoncini for guidance on iterative projection algorithms, and anonymous referees for useful suggestions.
Publisher Copyright:
© 2020 The Authors. Biometrics published by Wiley Periodicals, LLC on behalf of International Biometric Society.
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Karim Anaya-Izquierdo
- Department of Mathematical Sciences - Senior Lecturer
- EPSRC Centre for Doctoral Training in Statistical Applied Mathematics (SAMBa)
- Institute for Mathematical Innovation (IMI)
- Centre for Mathematics and Algorithms for Data (MAD)
- Centre for Mathematical Biology
Person: Research & Teaching