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Table 1 Covariates for constrained randomization

From: EVITA Dengue: a cluster-randomized controlled trial to EValuate the efficacy of Wolbachia-InfecTed Aedes aegypti mosquitoes in reducing the incidence of Arboviral infection in Brazil

Covariate Rationale Balancing criterion
Socioeconomic status (SES), measured by dichotomizing INSE scores into two categories (> 3 vs ≤3) SES may predict arboviral infection risk Each arm within ±5% of overall proportion
Population density Population density may predict arboviral infection risk Each arm within ±5% of overall population density
Number of students in grades 1 and 2 combined Proxy for age of participants to be enrolled in a given cluster. Age is predictive of individual arboviral infection risk. Each arm 45–55% of total number