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Table 1 Estimates of the Minimum Detectable Difference (MDD) for trial with 20 clusters per arm, to detect an increase in an event rate from 40%

From: Sample size calculations for cluster randomised controlled trials with a fixed number of clusters

  Power = 80% Power = 90%
  40% vs 50% MDD 40% vs 50% MDD
ICC = 0.005 n I = 385 N/A n I = 515 N/A
  n C = 440   n C = 600  
  m = 22   m = 30  
ICC = 0.07   MDD = 12%   MDD = 14%
   n I = 267   n I = 262
   n C = 3,780   n C = 2,920
   m = 189   m = 146