Hello everybody,
I would like to perform a sample size calculation for a study in parallel design, 3 arms.
I do not use the GLMPOWER procedure but use the following code:
proc power ;
twosamplemeans
alpha=0.017
meandiff=mean difference
stddev=estimated stddev
power=.8
npergroup=.
;
run ;
In fact, I adjust the alpha level using a Bonferonni correction (0.05/3=0.017).
Is this approach a good one? If not, do you have any suggestions?
Thanks a lot in advance for your answer.
Best,
Take a look at Example 71.1 One-Way ANOVA in the POWER Procedure, or look at PROC GLMPOWER Example 44.1. The latter has an explicitly worked example for calculation of sample size.
Steve Denham
Take a look at Example 71.1 One-Way ANOVA in the POWER Procedure, or look at PROC GLMPOWER Example 44.1. The latter has an explicitly worked example for calculation of sample size.
Steve Denham
Thanks a lot Steve!
Do you think the approach I describe is also correct?
Best,
The Bonferroni correction is almost always too conservative, and consequently will lead to an increased sample size needed to detect a fixed difference with given power.
Steve Denham
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