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.