I am so new to R and I am trying to estimate Panel Unit Root with purtest command. For the last hours I was only able to load the data and install the packages. I have error when I use the following command line:


purtest(rgdp, pmax = 4, exo = "intercept", test = "madwu")


It may be totally wrong but this the only thing I understood from the help file. Can anyone tell me where is the mistake here.
Thankksss a lot.