To avoid angry replies, let me first say that I know that the use of Type III sums of squares is controversial, and that some statisticians recommend instead that significance be judged using the non-marginal terms in the ANOVA. However, given that type III SS is also demanded by some… is there a function (equivalent to drop1 for lm) to obtain type III sums of squares for mixed models using the lme function? Bill Shipley Associate Editor, Ecology North American Editor, Annals of Botany Département de biologie, Université de Sherbrooke, Sherbrooke (Québec) J1K 2R1 CANADA Bill.Shipley@USherbrooke.ca <http://callisto.si.usherb.ca:8080/bshipley/> http://callisto.si.usherb.ca:8080/bshipley/ [[alternative HTML version deleted]]
On Thu, 11 Dec 2003, Bill Shipley wrote:> To avoid angry replies, let me first say that I know that the use of > Type III sums of squares is controversial, and that some statisticians > recommend instead that significance be judged using the non-marginal > terms in the ANOVA. However, given that type III SS is also demanded by > someis there a function (equivalent to drop1 for lm) to obtain type> III sums of squares for mixed models using the lme function?I don't think you want SSq for a non-least-squares fit. Changes in AIC are computed by dropterm() in MASS for lme fits (and possibly also by drop1: I have not checked). -- Brian D. Ripley, ripley at stats.ox.ac.uk Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595
Dear Bill, You can obtain marginal tests using anova(your.lme.object, type = "marginal") (If you are going to compare output, note that marginal tests when using non-orthogonal contrasts ---SAS and treatment--- might give you unexpected results, last time I checked). R. On Thursday 11 December 2003 19:40, Bill Shipley wrote:> To avoid angry replies, let me first say that I know that the use of > Type III sums of squares is controversial, and that some statisticians > recommend instead that significance be judged using the non-marginal > terms in the ANOVA. However, given that type III SS is also demanded by > someis there a function (equivalent to drop1 for lm) to obtain type> III sums of squares for mixed models using the lme function? > > > > Bill Shipley > > Associate Editor, Ecology > > North American Editor, Annals of Botany > > D?partement de biologie, Universit? de Sherbrooke, > > Sherbrooke (Qu?bec) J1K 2R1 CANADA > > Bill.Shipley at USherbrooke.ca > > <http://callisto.si.usherb.ca:8080/bshipley/> > http://callisto.si.usherb.ca:8080/bshipley/ > > > > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help at stat.math.ethz.ch mailing list > https://www.stat.math.ethz.ch/mailman/listinfo/r-help-- Ram?n D?az-Uriarte Bioinformatics Unit Centro Nacional de Investigaciones Oncol?gicas (CNIO) (Spanish National Cancer Center) Melchor Fern?ndez Almagro, 3 28029 Madrid (Spain) Fax: +-34-91-224-6972 Phone: +-34-91-224-6900 http://bioinfo.cnio.es/~rdiaz PGP KeyID: 0xE89B3462 (http://bioinfo.cnio.es/~rdiaz/0xE89B3462.asc)