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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