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02-12-2015 06:41 AM

**Background:** I calcualted the sample size for 2 groups with the response is binary data, and the proportion is the proportion of responders. The two group have same size. Target to test the non-inferiority between the proportion of group 1 and group 2.

**Size calculation Code:**

proc power;

twosamplefreq alpha=0.05 test=pchi sides=U npergroup=24 nullproportiondiff=-0.3

refproportion=0.9

proportiondiff=-0.06 power=.;

run;

**Question: **Since this power calculation is based on the** Pearson Chi-square test**, how could I reach the aim to test non-inferiority test of following Hypothesis testing by use of **Chi-square Test?**:

H0: proportion of group 1 - (minus) proportion of group 2 greater than or equal to -0.03 (0.03 is the margin)

vs

H1: proportion of group 1 - (minus) proportion of group 2 less than -0.03 (0.03 is the margin)

The criteria to conclude: The 95% confidence interval of the proportion differences based on Chi-square test will be calculated and the non-inferiority will be concluded if the **LOWER bound of **the confidence interval is greater than -0.3.

**What I found is: ** The only test I found in SAS manual and below link is by use of **WADL** test, and there is **NO** Chi-square test available to use. Could you tell me what should I do to analyze the data? Just continue to use the WALD test, and conclude the noninferiority if the 95% confidence interval lower bound exceeds -0.3?

The following code is the dummy data I created and the code to test by use of WALD test, please help me on my questions, thanks.

data pd1;

input grp $ response count;

datalines;

grp1 1 20

grp1 0 4

plcb 1 18

plcb 0 6

;

run;

/*Do non-inferiority test by Chi-square test*/

proc freq data=pd1;

tables grp*response/alpha=0.025 riskdiff(noninf column=2 correct margin=0.3);/*noninf:non-inferiority test; margin: the margin want to detect*/

weight count;/*count: then number of responders*/

run;

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02-12-2015 06:42 AM

Here is the link I talked above: http://support.sas.com/documentation/cdl/en/procstat/63104/HTML/default/viewer.htm#procstat_freq_a00...

Message was edited by: frank Green Nobody would like do me a favor?

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02-20-2015 08:46 AM

Hello Jack,

I also have the same problem.

I search quite a lot how to solve it but found no answer anywhere. I end up using excel and just apply the formula.