Dear all,
I have tried to merge two cross sections (crossA and crossB) as follows, both
crossA and crossB include the same variables, e.g., ID,y,x1,x2:
Panel <- merge(crossA,crossB,by="ID")
I have, thereafter, tried to run the following pooled OLS:
OLS <- lm(Panel$y~Panel$x1+Panel$x2)
and have received the following error message "Error in model.frame(formula,
rownames, variables, varnames, extras, extranames, : invalid variable type"
I would be very grateful for help. At the moment, I believe that I have tried
everything.
Thanks in advance,
Sophie