Is it meaningful to run 2 different sets of contrasts on a model , or is there some redundancy somewhere ? For example,I have a model : tcons ~ group
where group is a factor with 3 levels ( A, B, C) I first run the model with the default contrasts (treatment), so I tested (A vs B) and (A vs C); but is it meaningful to also carry on a 2nd analysis with an other set of contrasts, to test B vs C ? ie c(0,-1,1) , in fit.contrasts gregmisc notation. I'v heard that the first set of contrast ( ie treatment default in the example) extracts all the "information" in the model, and that a second analysis with an other set of contrasts was not meaningful. Thanks for help. -- Robert Espesser Laboratoire Parole et Langage UMR 6057, CNRS 29 Av. Robert Schuman 13621 AIX (FRANCE) Tel: +33 (0)4 42 95 36 26 Fax: +33 (0)4 42 59 50 96 http://www.lpl.univ-aix.fr/~espesser mailto:[EMAIL PROTECTED] ______________________________________________ [EMAIL PROTECTED] mailing list http://www.stat.math.ethz.ch/mailman/listinfo/r-help
