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Sample size calculation for a non-inferiority trial with POWER procedure

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Contributor
Posts: 25

Sample size calculation for a non-inferiority trial with POWER procedure

Dear all,

I'd like to ask you about sample size calculation for a non-inferiority trial with POWER procedure.

What is the formula for calculating samplesize used in POWER procedure?

Sample SAS code is as follows:

PROC POWER;

TWOSAMPLEFREQ

TEST = PCHI

SIDES = U

ALPHA = .025

GROUPPROPORTIONS = (.75 .80) 

NULLPROPORTIONDIFF=-.10

POWER = .8

Ntotal = .

;

RUN;

Thanks in advance,

Yasu

Occasional Contributor
Posts: 15

Re: Sample size calculation for a non-inferiority trial with POWER procedure

Hello Yasu!

One of the best books about it is "Chow, S.C.; Shao, J.; Wang, H. 2003. Sample Size Calculations in Clinical Research. Marcel Dekker. New York."

So your formula looks like:

n = (Zα/2+Zβ)2 * (p1(1-p1)+p2(1-p2)) / (p1-p2-NImargin)2

Zα/2=1.96

Zβ=0.84


better late than never

Andrei

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