Take a look at contrast package. It has functions to handle with user
contrasts. Below you have a reproducible and minimal example using
contrast's functions.
da <- expand.grid(A=factor(paste("A", 1:3, sep="")),
B=factor(paste("B", 1:4, sep="")), rep=1:4)
eta <- model.matrix(~A*B, da)%*%matrix(c(0, 1,2, -1,0,1, 0,1,2, 0,0,0))
da$y <- rnorm(da$A, mean=eta, sd=1)
g0 <- lm(y~A*B, data=da)
anova(g0)
require(contrast)
c0 <- contrast(g0,
list(B="B1", A="A1"),
list(B="B2", A="A1"))
c0
c0$X
Walmes.
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..ooo0
...................................................................................................
..(....)... 0ooo... Walmes Zeviani
...\..(.....(.....)... Master in Statistics and Agricultural
Experimentation
....\_)..... )../.... walmeszevi...@hotmail.com, Lavras - MG, Brasil
............
(_/............................................................................................
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