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Table 3 Estimated power in Nigeria and Kenya

From: Incentivizing appropriate malaria case management in the private sector: a study protocol for two linked cluster randomized controlled trials to evaluate provider- and client-focused interventions in western Kenya and Lagos, Nigeria

  Estimated power in Nigeria Estimated power in Kenya
Primary outcome comparison 4-arm design with a total of 48 clusters (alpha = 0.05/3 = 0.0167) 3-arm design with a total of 40 clusters (alpha = 0.05/2 = 0.025)
Expected effect size Power Expected effect size Power
Combined incentives (PD + CD) vs. control 68% (PD + CD) − 21% (control) =
47 percentage points
100% 23% (PD + CD) − 7% (control) = 16 percentage points 99.1%
Combined incentives (PD + CD) vs. provider-incentives (PD) 68% (PD + CD) − 24% (PD) = 44 percentage points 100% NA NA
Combined incentives (PD + CD) vs. Client-incentives (CD) 68% (PD + CD) − 38% (CD) = 30 percentage points 98.8% 23% (PD + CD) − 12% (CD) = 11 percentage points 80.2%
  1. Expected effect size, change in percentage of ACTs taken by clients with a positive test. Since our outcome is a composite measure of testing rates and adherence to the test result, our sample size calculations accounted for the fact that not everyone who we interview will have taken an ACT. For Nigeria, power was calculated based on 12 clusters per arm for a total of 48 clusters. For Kenya, power was calculated based on 13 clusters per arm. In practice an additional cluster will be available in the control arm in Kenya, for a total of 14 clusters in this arm, for a total of 40 clusters