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Table 4 Power analysis, and numbers needed for non-inferiority study

From: Trochanteric osteotomy versus posterolateral approach: function the first year post surgery. A pilot study

  Power current study Numbers needed per approach (total) *
HHS 21.1% 398 (796)
WOMAC pain 15.2% 469 (930)
WOMAC stiffness 33.4% 278 (556)
WOMAC function 10.7% 1197 (2394)
  1. * numbers needed to perform a non-inferiority study, with α = 0.05 and power of 0.8 (1 - β), based on the results of the current study