Contrast Matrix for Constraints about the Mean
Return a matrix of contrasts for constraints about the mean.
contr.mean(n, contrasts = TRUE)
n |
A vector of levels for a factor or the number of levels. |
contrasts |
A logical value indicating whether or not contrasts should be computed. |
This function corrects contr.sum to display labels properly.
A matrix of computed contrasts with n rows and k
columns, with k=n-1 if contrasts is TRUE and
k=n if contrasts is FALSE. The columns of the
resulting matrices contain contrasts which can be used for coding a
factor with n levels.
oldop <- options(contrasts=c("contr.sum","contra.poly"))
y <- rnorm(30)
x <- gl(3,10,labels=c("First","Second","Third"))
glm(y~x)
options(contrasts=c("contr.mean","contra.poly"))
x <- gl(3,10,labels=c("First","Second","Third"))
glm(y~x)
options(oldop)Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.