| contrast.bayes {arm} | R Documentation |
Contrast Matrices
Description
Return a matrix of contrasts used in bayesglm.
Usage
contr.bayes.unordered(n, base = 1, contrasts = TRUE)
contr.bayes.ordered (n, scores = 1:n, contrasts = TRUE)
Arguments
n |
a vector of levels for a factor, or the number of levels. |
base |
an integer specifying which group is considered the baseline
group. Ignored if |
contrasts |
a logical indicating whether contrasts should be computed. |
scores |
the set of values over which orthogonal polynomials are to be computed. |
Details
These functions are adapted from contr.treatment and contr.poly
in stats package. The purpose for these functions are to keep
the baseline levels of categorical variables and thus to suit the use of
bayesglm.
contr.bayes.unordered is equivalent to contr.treatment whereas
contr.bayes.ordered is equivalent to contr.poly.
Author(s)
Yu-Sung Su suyusung@tsinghua.edu.cn
See Also
C,
contr.helmert,
contr.poly,
contr.sum,
contr.treatment;
glm,
aov,
lm,
bayesglm.
Examples
cat.var <- rep(1:3, 5)
dim(contr.bayes.unordered(cat.var))
# 15*15 baseline level kept!
dim(contr.treatment(cat.var))
# 15*14