Full_Name: Francisco Vera Version: 1.6.2 OS: Windows XP Submission from: (NULL) (66.20.153.135) When I run the following code: m1<-lm(y~A*B) m2<-lm(y~A/B) anova(m1) anova(m2) I obtain the results I want from both, the cross classified and the nested model, except for the labeling. The terms for m1 are A, B and A:B (good); the terms for m2 are A and A:B (wrong). I would expect for terms in m2 to be A and B%in%A. The same mistake happens if I use the formula "y~A+B%in%A" instead of "y~A/B". The values for the term A:B in m2 are correct, they correspond to B%in%A and are different from A:B of m1. The only problem is the labeling.
Labeling in lm() (PR#2785)
2 messages · veraf@stat.sc.edu, Peter Dalgaard
veraf@stat.sc.edu writes:
Full_Name: Francisco Vera Version: 1.6.2 OS: Windows XP Submission from: (NULL) (66.20.153.135) When I run the following code: m1<-lm(y~A*B) m2<-lm(y~A/B) anova(m1) anova(m2) I obtain the results I want from both, the cross classified and the nested model, except for the labeling. The terms for m1 are A, B and A:B (good); the terms for m2 are A and A:B (wrong). I would expect for terms in m2 to be A and B%in%A. The same mistake happens if I use the formula "y~A+B%in%A" instead of "y~A/B". The values for the term A:B in m2 are correct, they correspond to B%in%A and are different from A:B of m1. The only problem is the labeling.
This is not a bug. The colon operator is equivalent to %in% (b%in%a is the same as a:b), and in both cases it describes the cross-terms effect after removal of the specified main effects. In the nested case, you just don't remove main efects of B because that doesn't make sense. Just because S-PLUS uses a different labeling it doesn't mean that R's is wrong.
O__ ---- Peter Dalgaard Blegdamsvej 3 c/ /'_ --- Dept. of Biostatistics 2200 Cph. N (*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918 ~~~~~~~~~~ - (p.dalgaard@biostat.ku.dk) FAX: (+45) 35327907