Table 5 Sample size calculations for the three RCTs including medical substudies

Primary outcome

Physical activity (BSA)

questionnaire study: physical activity (BSA);

medical examinations: VO_{2 max}

Weight loss

Questionnaire study + medical examinations: weight loss

Abstinence from smoking

Effect assumption for primary outcome

effect size = 0.25

questionnaire study: effect size = 0.25 ; medical examinations: effect size = 0.45

Effect size = 0.50

Effect size = 0.50

15% in intervention group versus 2% in control group

Required case-number results (two-sided, alpha = 0.05, beta = 0.80)

253 (for each intervention group IG and control group CG)¹

79 (for each IG and CG)²

253 (for each IG and CG)^1,3

64 (for each IG and CG)²

77 (for each IG and CG)

(assumed dropout)

minimally required sample size

(50%)

506 (for each IG and CG)

(15%)

93 (for each IG and CG)

(50%)

506 (for each IG and CG)

(15%)

75 (for each IG and CG)

(50%)

154 (for each IG and CG)

total sample size (IG + CG + ca. 10% buffer for questionnaire study

(506 + 506) × 1.1

N = 1.114

(93 + 93)

N = 186

(506 + 506) × 1.1

N = 1.114

(75 + 75)

N = 150

(154 + 154) × 1.1

N = 339