Re: [R] Contrast anova multi factor

2015-04-26 Thread peter dalgaard
> On 26 Apr 2015, at 17:30 , Thierry Onkelinx wrote: > > Dear Mario, > > The interpretation is the same: the average at the reference situation > which is the group that has f1 == "f1 level1" and f2 == "f2 level1". A little more precisely: It is the estimate of the expected value at the refer

Re: [R] Contrast anova multi factor

2015-04-26 Thread Thierry Onkelinx
The parameter is different because the model without intercept assumes that effect of f1 is independent on the effect of f2. So you force f1b:f2ll to be 0. The interpretation is the same. The fit is conditional on the model (interaction or no interaction). ir. Thierry Onkelinx Instituut voor natu

Re: [R] Contrast anova multi factor

2015-04-26 Thread Mario José Marques-Azevedo
​Dear Thierry, That is the problem. I read that interpretation is the same, but the Intercept value of summary is different: The mean of level "a" of f1 and level "I" of f2 (first level of each factor) is 0.7127851. When I run model with interaction term: summary.lm(aov(y~f1*f2,data=dt)) Coeff

Re: [R] Contrast anova multi factor

2015-04-26 Thread Thierry Onkelinx
Dear Mario, The interpretation is the same: the average at the reference situation which is the group that has f1 == "f1 level1" and f2 == "f2 level1". Best regards, ir. Thierry Onkelinx Instituut voor natuur- en bosonderzoek / Research Institute for Nature and Forest team Biometrie & Kwaliteits

[R] Contrast anova multi factor

2015-04-26 Thread Mario José Marques-Azevedo
Hi all, I am doing anova multi factor and I found different Intercept when model has interaction term. I have the follow data: set.seed(42) dt <- data.frame(f1=c(rep("a",5),rep("b",5)), f2=rep(c("I","II"),5), y=rnorm(10)) When I run summary.lm(aov(y ~ f1 * f2,