Table 2

Approximate sample sizes required for non-inferiority comparison of proportions

True proportion in active control

Non-inferiority bound using 10% margin

Approximate sample size per group assuming 1:1 randomization to new treatment and control required under:


Equal effects

5% benefit

10% benefit


0.1

0.09

19,200

8,725

5,050


0.2

0.18

8,500

3,900

2,250


0.3

0.27

4,970

2,260

1,300


0.4

0.36

3,200

1,450

825


0.5

0.45

2,100

1,000

550


0.6

0.54

1,440

640

360


0.7

0.63

930

405

225


Sample sizes calculated using Pass 2008 methods for non-inferiority tests of two independent proportions, using the Z statistic with continuity correction and pooled variance, with a target power of 90% and α level of 0.025.

Schumi and Wittes Trials 2011 12:106   doi:10.1186/1745-6215-12-106

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