Dear Hardouin, It has already been mentioned that the Anova() function in the car package has a name beginning with an uppercase "A".
There are some other problems here as well: (1) Unless you've written a contrasts function called sum(), and even if you have, contrasts=sum isn't going to do anything. The contrasts argument is supposed to be a list. See ?lm and ?contr.sum. (2) The Anova() function in the car library doesn't calculate "type-I" sums of squares; you can use anova() for this -- as you've done inadvertently. (3) The type argument to the Anova() function takes *one* of "II" or "III" as a value. See ?Anova. (4) You describe this as an analysis of covariance. Type III sums of squares for the "main" effects won't be sensible here unless the covariates are expressed as deviations from their means (or some other reference point). John > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Hardouin Lo�c > Sent: Friday, March 12, 2004 3:46 AM > To: [EMAIL PROTECTED] > Subject: [R] performing type III > > > Sorry to have not precised that I used the anova function in > the car package but I did. > I try to fit clutch size with two covariables and a factor > (with two levels). My purpose is to compare results with type > I and III sum of squares and furhter perform model > simplification. The data set contains no missing value. > The model run and provided only type I response with the > warning message (see below) > > > sq<-lm(tponte~logavril*reldponte*exp,data=wa,contrasts=sum) > > anova(sq,type=c("I","III")) > Analysis of Variance Table > > Response: tponte > Df Sum Sq Mean Sq F value Pr(>F) > logavril 1 27.930 27.930 52.5041 1.385e-11 *** > reldponte 1 23.442 23.442 44.0670 3.984e-10 *** > exp 1 2.657 2.657 4.9940 0.02672 * > logavril:reldponte 1 0.281 0.281 0.5292 0.46795 > logavril:exp 1 0.925 0.925 1.7383 0.18911 > reldponte:exp 1 0.016 0.016 0.0307 0.86105 > logavril:reldponte:exp 1 1.052 1.052 1.9771 0.16150 > Residuals 172 91.497 0.532 --- > > Warning message: > Models with response "NULL" removed because response differs > from model > 1 in: anova.lmlist(object, ...) > > > > Hope to be clearer, > Thanks, > > Alex > > > > > > > ______________________________________________ > [EMAIL PROTECTED] mailing list > https://www.stat.math.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! > http://www.R-project.org/posting-guide.html ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
