well thanks anyway even just for replying, i understand the lack of information causes no response... but if no one tells me that they need more information how could i send. anyway here more information about the procedure that i am applying to define the model
after reading and attaching my data; eco1=(wwater>0) eco2=(wgas>0) eco3=(wgarbage>0) eco4=(noise>0) eco=(eco1>0|eco2>0|eco3>0|eco4>0) inno=(researchtot>0|purtot>0) RD=(researchtot>0) all of the above are my dummies as you can understand lnLP=lnQ-lnL # then i define my dependent variable then, newdata = plm.data(ds,index=c("stno","year")) # individual and time indexes after that i define the followings; dsnri3LP=plm(lnLP~lnC+lnL+lnM+lnE+eco+eco*lnE+eco*lnM+inno+inno*eco, data=newdata,model="random") dsnfi3LP=plm(lnLP~lnC+lnL+lnM+lnE+eco+eco*lnE+eco*lnM+inno+inno*eco, data=newdata,model="within") which are working quite well and when i define the effect=" twoways", model="within" dsnfi3LP=plm(lnLP~lnC+lnL+lnM+lnE+eco+eco*lnE+eco*lnM+inno+inno*eco, data=newdata,effect="twoways",model="within") i get the following error Error in rep.int(c(1, numeric(n)), n - 1L) : negative length vectors are not allowed so i hope this time i could send sufficient information about the process and the error, sorry that i cant send my data since it is more than 60MB. Thanks for everyone again for the possible help -- View this message in context: http://n4.nabble.com/plm-package-twoways-effect-problem-tp1774246p1819172.html Sent from the R help mailing list archive at Nabble.com. [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.