Dear all,
I have two PFS rate for two groups (i.e 71% and 82%) and would like to pooled both, in order to get one PFS rate. First, I wanted to calculate the mean (71+82/2) which is not an approbiate approach. Based on the pfs rate I would like to perfom sample size calculation.
David Morse
Hello Gracia,
If the two groups were of equal size, then ordinary mean of the two percent values would work. Otherwise, you'll need to take into account sample sizes (e.g., go with a weighted mean estimate):
proportion = (X1 + X2) / (N1 + N2)
where "X" represents surviving cases in sample 1 or sample 2, and
"N" indicates total cases in sample 1 or sample 2.
Good luck with your work.
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