## R-Code for Power in 2×2 Cross-over [🇷 for BE/BA]

Hello Brus,

» I am not an expert in R, and I am trying to adapt your example of power calculation with plot replesentation, but for the calculation of the sample size. My objetive is to plot a graphicala representation with ratio in X axis and sample size in Y axis and setting the CV and power as a fixed value.

Here's something basic to get you started. I assume you already have the PowerTOST package on your system.

Try.this=function(CV=0.2, tpow=0.8) {  library(PowerTOST)  x=c(85:120)/100  y=rep(NA, length(x))  for (i in 1:length(x))   y[i]= sampleN.TOST(CV=CV, targetpower=tpow, theta0=x[i])[1,7]  plot(x,y, col="red", xlab ="GMR", ylab="Sample size")  lines(x,y, col="red")  return(0) } Try.this(CV=0.3, tpow=0.9)

Can be refined with designs and multipanel options and what not.
PS: Correct, I am not entirely comfy with the  tapply, sapply, apply family of functions.

Pass or fail!
ElMaestro