Thanks, Rich. I didn't notice that! -- Bert Bert Gunter
"The trouble with having an open mind is that people keep coming along and sticking things into it." -- Opus (aka Berkeley Breathed in his "Bloom County" comic strip ) On Mon, Aug 22, 2016 at 1:43 PM, Richard M. Heiberger <r...@temple.edu> wrote: > The problem is that you have 12 observations and 1+2+10=13 degrees of freedom. > There should be 1 + 2 + 8 = 11 degrees of freedom. > Probably one of your variables is masked by something else in you workspace. > Protect yourself by using a data.frame > >> tmp <- data.frame(A=factor(c(1,1,1,1,1,1,2,2,2,2,2,2)), > + B=factor(c(1,1,2,2,3,3,1,1,2,2,3,3)), > + y=rnorm(12)) >> mod <- aov(y ~ A+B, data=tmp) >> summary(mod) > Df Sum Sq Mean Sq F value Pr(>F) > A 1 1.553 1.553 1.334 0.281 > B 2 3.158 1.579 1.357 0.311 > Residuals 8 9.311 1.164 > > On Mon, Aug 22, 2016 at 11:15 AM, Justin Thong <justinthon...@gmail.com> > wrote: >> Something does not make sense in R. It has to do with the question of >> balance and unbalance. >> >> *A<-factor(c(1,1,1,1,1,1,2,2,2,2,2,2))* >> *B<-factor(c(1,1,2,2,3,3,1,1,2,2,3,3))* >> *y<-rnorm(12)* >> *mod<-aov(y~A+B)* >> >> I was under the impression that the design is balanced ie order does not >> effect the sums of squares. However, when I compute the anova R reports >> that the Estimated Effects are Unbalanced. I thought that when all >> combinations of levels of A and B have equal replications then the design >> is called balanced. But, R tends to think that when not all levels of A and >> levels of B have equal replication, then the "Estimated Effects are >> unbalanced".... Is this the same as the design being unbalanced? Because >> for the example below, where the error occured, the order does not matter >> (which make me think that the design is balanced). >> >> >> *Call:* >> * aov(formula = y ~ A + B)* >> >> *Terms:* >> * A B Residuals* >> *Sum of Squares 0.872572 0.025604 16.805706* >> *Deg. of Freedom 1 2 10* >> >> *Residual standard error: 1.296368* >> *Estimated effects may be unbalanced* >> -- >> Yours sincerely, >> Justin >> >> *I check my email at 9AM and 4PM everyday* >> *If you have an EMERGENCY, contact me at +447938674419(UK) or >> +60125056192(Malaysia)* >> >> [[alternative HTML version deleted]] >> >> ______________________________________________ >> R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see >> https://stat.ethz.ch/mailman/listinfo/r-help >> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html >> and provide commented, minimal, self-contained, reproducible code. > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
