Thank you very much for your thorough reply. It has helped a lot. I have one more question. If the correlation is zero in the proc power for paired equivalents test, should I expect that the calculated power of the paired equivalents test is the same as the power for not paired equivalents test? When I run the following two codes I get different results. The power for the paired test is 0.710 while the power for the not paired equivalents test is 0.899. Why there is a difference, if the standard deviations, mean difference and sample size are the same in both cases? proc power; pairedmeans TEST=EQUIV_DIFF meandiff=1 pstds=(2,2) power = . /* to be calculated*/ npairs =3 corr = 0 alpha =0.05 upper = 7 lower =-7; ods output output = power_paired; run; proc power; twosamplemeans TEST=EQUIV_DIFF meandiff=1 stddev=2 power = . /* to be calculated*/ ntotal =6 alpha =0.05 upper = 7 lower =-7; ods output output = power_twosample; run;
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