contrast {rmutil} | R Documentation |
Contrast Matrix for Constraints about the Mean
Description
Return a matrix of contrasts for constraints about the mean.
Usage
contr.mean(n, contrasts = TRUE)
Arguments
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. |
Details
This function corrects contr.sum
to display labels properly.
Value
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.
See Also
Examples
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)
[Package rmutil version 1.1.10 Index]