Question

10.88 In planning the study it was anticipated that 400 subjects would be enrolled per group and that the 3-year mortality risk would be 36% in the late start group and 26% in the early start group. How much power would the study have if it had occurred under the planned mortality rates and sample size?

Answer 1

Answer:-

By use the power formula:

In this case, p1 = 0.26, p2 = 0.36, N1 = 400, N2 = 400, p̅ = 0.31, Δ = 0.10, z1α/2 = z.975 = 1.96.

Thus,

= Φ[3.076 – 1.972] = Φ(1.104) = 0.865.

Thus, the study would have about 87% power.

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