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;
