dfM1<-24 # degrees of freedom of M1

dfM2<-27 # degrees of freedom of M2

delta<-dfM2*.05ˆ2 # define delta in the alternative hypothesis

alpha<-.05

cv<-qchisq(1-alpha,df=dfM2-dfM1) # Critical value under the null hypothesis

for (n in 1:100000) {

power<-1-pchisq(cv,df=dfM2-dfM1,ncp=n*delta)

if (power>=.80) break # reach the desirable power

}

N<-n+1

print(N)