Sample size calculation
malaria
MALARIA
For the intervention evaluation, malaria incidence in school age children from Handeni was assumed similar to that derived from the Demographic Health Information System 2 (DHIS2) for the same district council (413 cases per 1000) and that the incidence would be reduced by 40% following intervention when compared to control. A sample size of 140 schoolchildren was to be followed from each cluster/school to document cases of malaria. The study assumed correlation coefficient k = 0.2, a power of 80% and type one error (α) of 0.05. Hence, five clusters were required for each of the intervention and control arms. Similar parameters were assumed for Kilindi DC and Handeni TC, but with slightly lower incidence (183 cases per 1000). In this, seven clusters/schools (distributed basing on number of wards ratio per council; 5 from Kilindi DC and 2 from Handeni TC) were required for each of the intervention and control wards from the two councils. To adjust for loss to follow-up, an attrition rate of 20% was considered from each ward/school. Therefore, a total of 4032 schoolchildren from 24 schools (i.e.1680 from Handeni DC, 672 from Handeni TC and 1680 from Kilindi DC) were expected to be enrolled in the study (Fig. 