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Table 3 Power calculations assuming 50 clusters allocated in a 1:1 ratio between treatment and controls to achieve power of 80%

From: The TIRS trial: protocol for a cluster randomized controlled trial assessing the efficacy of preventive targeted indoor residual spraying to reduce Aedes-borne viral illnesses in Merida, Mexico

TIRS efficacy No. events Total effective sample size No. per cluster, unadjusted No. per cluster, adjusted* Total sample size, adjusted*
70% 28 1038 74 92 4600
75% 22 870 43 54 2700
80% 18 734 30 37 1850
90% 12 534 17 21 1050
  1. *Adjusted for a 20% loss to follow-up