Dear All, I'm looking to perform an ANOVA between two nested panel fixed effects models. I tried with anova, as well as with waldtest. anova tells me there is no method available for plm objects, while waldtest tells me my models are not nested. I think they are instead. The difference between the two models is that in the second I let the regression coefficients of a given variable variate according to a factor. MODEL 1 depFE.plm = plm(urate ~ l1_urate + month, model = "within", data = unempl_data1, effect = "individual") MODEL 2 depLDFE.plm = plm(urate ~ factor(ID):l1_urate + month, model = "within", data = unempl_data1, effect = "individual") anova> anova(depFE.plm, depLDFE.plm)Errore in UseMethod("anova") : no applicable method for 'anova' applied to an object of class "c('plm', 'panelmodel')" waldtest> waldtest(depFE.plm, depLDFE.plm)Errore in modelCompare(objects[[i - 1]], objects[[i]], vfun = vcov.) : models are not nested Did anyone code a plm method for anova? OR Does anyone know why according to waldtest my models are not nested? Thanks Roberto ******************** Roberto Patuelli, Ph.D. Istituto Ricerche Economiche (IRE) (Institute for Economic Research) Università della Svizzera Italiana (University of Lugano) via Maderno 24, CP 4361 CH-6904 Lugano Switzerland Phone: +41-(0)58-666-4166 Fax: +39-02-700419665 Email: roberto.patuelli@usi.ch Homepage: http://www.people.lu.unisi.ch/patuellr ******************** [[alternative HTML version deleted]]