To glm-experts Is there a simple way of counting degrees of freedom when modeling interactions with a lot of empty cells? I am thinking of an example of McCulagh & Nelder where glm gives df=13 but there is only scope for df=10 due to empty cells. best regards Helgi -- Helgi Tomasson FAX: 354-552-6806 University of Iceland PHONE:354-525-4571 Faculty of Economics and Business Administration email:helgito at rhi.hi.is Oddi v/ Sturlugotu IS-101 Reykjavik ICELAND -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._