Dear Community, I emphasize the use of graphical methods to examine residuals for a Panel model and want to plot the Standard Deviation of residuals by group. I used the following for plotting residuals by group:>library(lattice)>xyplot((residuals(fixed.reg1.1))~countrynr,data=data.plm)But I have no idea how to adjust this for the SD of Residuals by group ? Thanks for attention and help! Katie [[alternative HTML version deleted]]