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Spatial regression and spillover effects in cluster randomized trials with count outcomes
Author(s) -
AnayaIzquierdo Karim,
Alexander Neal
Publication year - 2021
Publication title -
biometrics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.298
H-Index - 130
eISSN - 1541-0420
pISSN - 0006-341X
DOI - 10.1111/biom.13316
Subject(s) - statistics , econometrics , count data , spatial analysis , mathematics , random effects model , spatial dependence , poisson regression , poisson distribution , medicine , population , meta analysis , environmental health
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 modeled 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 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.