Re: [R] Power graph for two Proportion

2014-06-17 Thread Adams, Jean 
Suga,

Perhaps something like this ...

library(pwr)
n - 50:100
power - pwr.2p.test(h=ES.h(0.4,0.2), n=n, sig.level=0.05,
alternative=greater)$power
plot(n, power)

Jean


On Mon, Jun 16, 2014 at 10:44 AM, Suganthie Jeyaganth suganthi...@yahoo.ca
wrote:

 Dear R mailing listers,
 I am try to find the different power calculation for

 p1=0.2 and p2=0.4 , with significant level=0.05  (one sided test)

 I would like to  have a graph   y -axis as a power and

 x-axis as a sample size .

 I run this command for different value of power. and get the n and power

 to draw a graph

 pwr.2p.test(h=ES.h(0.4,0.2), power = 0.87,
 sig.level=0.05,alternative=greater)


 Is there is any easy way i can do this in R.
 Thanks


 Suga
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Re: [R] Power graph for two Proportion

2014-06-17 Thread Jim Lemon 
On Tue, 17 Jun 2014 10:30:17 AM suganthiny cumarasamy wrote:
 Dear R mailing listers,
 
 I am try to find the different power calculation for
 p1=0.2 and p2=0.4 , with significant level=0.05  (one sided test)
 I would like to  have a graph   y -axis as a power and
 x-axis as a sample size .
 
 I run this command for different value of power. and get the n and 
power
 pwr.2p.test(h=ES.h(0.4,0.2), power = 0.87,
 sig.level=0.05,alternative=greater)
 
  Is there is any easy way i can do power graph using the two proportion 
in
 R.
 
Hi Suga,
I'm not familiar with pwr.2p.test, but if it takes a vector of power values, 
you could do something like this:

# get a vector of sample sizes for different values of power
# it probably won't be this straightforward
powers-seq(0.5,0.95,by=0.05)
sample_sizes-pwr.2p.test(h=ES.h(0.4,0.2),power=powers,
 sig.level=0.05,alternative=greater)
plot(sample_sizes,powers)

Jim

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