Hello, i know there are several functions on r to calculate the power of a test. f.e the functions of pwr packet. In this packet the use the power function (1-\beta) to calculate. My question is how we get this function for anova (pwr.anova.test)? I know that 1-\beta=P(H1|H1) = P(F>F_[1-\alpha,k-1,N-k]) = 1-P(F<F_[1-\alpha,k-1,N-k]) 1-P(MQE/MQR<F_[1-\alpha,k-1,N-k]) = ??....?? = 1-P(F[k-1,N-k]<F_[1-\alpha,k-1,N-k]-k*n*f^2) = p.body = pf(qf(\alpha,k-1,(n-1)k,low=F),k-1,(n-1)k,k*n*f^2,low=F) With f^2 the effect and k*n*f^2 ncp but how does the function which has a F[k-1,N-k] distribution look like? It has to be the (variance between groups/df)/(variance within groups/df)-k*n*f^2, but how can I write these so that I see the dirstribution. I have never found the exact way how to get to this formula. So may you can help. Thanks a lot. -- View this message in context: http://r.789695.n4.nabble.com/calculating-power-function-tp4682396.html Sent from the R help mailing list archive at Nabble.com.