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Table 3 Sample size and power calculations

From: Centering and Racial Disparities (CRADLE study): rationale and design of a randomized controlled trial of centeringpregnancy and birth outcomes

  Power = 80% Power = 90%
Aim 1 RR = 0.50 RR = 0.60 RR = 0.70 RR = 0.50 RR = 0.60 RR = 0.70
P0 = 0.10 435 721 1,356 582 965 1,814
P0 = 0.13 326 540 1,014 436 723 1,356
P0 = 0.16 258 427 800 345 571 1,070
Aim 2 RD = 0.01 RD = 0.014 RD = 0.018 RD = 0.01 RD = 0.014 RD = 0.018
P0 = 0.02 2,319 1,027 526 3,103 1,374 704
P0 = 0.03 3,826 1,799 995 5,121 2,048 1,332
P0: the RD of PTB in IPNC group; RR: relative risk
  1. Abbreviation: RD = risk difference