Thanks so much for your prompt response. Still can't figure out how to set up "groupns" in the example you mentioned to complete the power analysis in my case. I have the weekly product sale in EQ in time series data(total 88 weeks) for the test group with mean=15,000, standard deviation=2,500 cv=16.42 and the control group with mean=38,856 and standard deviation=4,700, cv=16.54. Should I use "groupns=(88 88)" in below? Thanks again for your insight. *********************************************************** proc power; twosamplemeans test=ratio meanratio = 0.7 to 1.2 by 0.1 nullratio = 1.10 sides = L alpha = 0.01 cv = 0.5 0.6 groupns = (300 180) power = .; plot x=effect step=0.05; run;
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