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Br J Ophthalmol 86:946-947 doi:10.1136/bjo.86.9.946
  • Editorial

The determination of sample size in controlled clinical trials in ophthalmology

Table 3

Predicted sample size for significance level 0.01 and statistical power 0.90 (in parentheses for power 0.80) under assumption of different success frequencies p versus q (refers to example 3)

q = 10% q = 20% q = 30% q = 40% q = 50%
p = 20% 382 (303)
p = 30% 122 (98) 553 (473)
p = 40% 64 (52) 158 (126) 668 (526)
p = 50% 40 (33) 77 (62) 179 (143) 725 (571)
p = 60% 28 (23) 46 (37) 83 (67) 186 (148) 732 (574)

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