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Table 2 Sample sizes required for different combinations of power and relative control versus intervention six-month abstinence rates

From: Nicotine patch preloading for smoking cessation (the preloading trial): study protocol for a randomized controlled trial

  

Trial with 80% power

Trial with 90% power

% prolonged abstinence in control

% prolonged abstinence in intervention

Number/arm

Number/arm

RR = 1.3

   

14

18.2

1249

1655

15

19.5

1150

1524

16

20.8

1064

1409

20

26

805

1065

RR = 1.4

   

14

19.6

734

970

15

21

676

893

16

22.4

625

825

20

28

471

622

RR = 1.5

   

14

21

490

646

15

22.5

451

594

16

24

416

549

20

30

313

412