Sample design and participation in the Educatel Study.

Educatel Brazil 2015/2016 was a cross-sectional study conducted by telephone interview with the aim of producing information on health and absenteeism in Brazilian schoolteachers. The nationally representative sampling plan was based on the simple stratified sampling method, with stratification defined to meet the analytical domains established for the study (five major geographic regions, two census areas, four age brackets, sex, three types of school administration, five types of teacher employment, and six grade levels) and selection by simple random sampling of teachers in each stratum. Teacher selection was based on the 2014 School Census conducted by the Brazilian National Institute for Educational Studies and Research "Anísio Teixeira". Of the 2,229,269 teachers recorded in the Census, 13,243 were selected. A total of 119,378 telephone calls were made, identifying 7,642 eligible teachers (57.7% of the total initially sampled). A total of 6,510 interviews were finally completed, for a response rate of 85.2%. At the end of data collection, sample weights were assigned to each of the teachers interviewed. These weighting factors are connected not only to the Educatel sample design, but also to the adjustment terms for treatment of non-response during the data collection process.