Since the modification of the power.prop.test() function in R 3.1.3
("power.t.test() and power.prop.test() now make use of the extendInt option of uniroot() and hence work in more extreme cases. (PR#15792)")
the function can display proportion over 1 without warning message.
power.prop.test(n=30, p1=0.90, p2=NULL, sig.level=0.05, power=0.8, alternative="two.sided", strict=TRUE)
Two-sample comparison of proportions power calculation
n = 30
p1 = 0.9
p2 = 1.030182
sig.level = 0.05
power = 0.8
alternative = two.sided
NOTE: n is number in *each* group
This was not the case before the modification.
Moreover, in ?power.prop.test(), the following sentence is not clear:
"If one of them is computed p1 < p2 will hold, although this is not enforced when both are specified".
Many thanks for your help.