Skip to main content

Table 6 Sample size calculation for a future definitive trial

From: Results of a feasibility cluster randomised controlled trial of a peer-led school-based intervention to increase the physical activity of adolescent girls (PLAN-A)

Between-arms difference in weekday MVPA (mins)

Power

N students (uninflated)

N students (inflated)

N Schools

10

90

560

800

12

10

80

420

600

10

8

90

700

1000

16

8

80

560

800

12

6

90

980

1400

20

6

80

840

1200

18

  1. The following parameters were used: cluster size = 70, ICC on weekday MVPA = 0.01 MVPA standard deviation = 20 minutes, correlation between baseline and follow-up MVPA = 0.4, 5 per cent two-sided alpha and inflation to account for 30% of participants not providing primary outcome data.
  2. Values in boldface represent the sample size values proposed for the primary outcome in a future definitive trial