| contrMat {multcomp} | R Documentation |
Computes contrast matrices for several multiple comparision procedures.
contrMat(n, type=c("Dunnett", "Tukey", "Sequen", "AVE",
"Changepoint", "Williams", "Marcus",
"McDermott", "Tetrade"), nlevel = NULL, base = 1)
contr.Dunnett(n, base = 1, contrasts=TRUE)
n |
a (possibly named) vector of sample sizes for each group or a vector of factor levels. |
type |
type of contrast. |
nlevel |
number of levels of two factors (for type="Tetrade"
only). |
contrasts |
a logical indicating whether contrasts should be computed. |
base |
an integer specifying which group is considered the baseline
group for Dunnett contrasts. Ignored if contrasts is FALSE. |
Computes the requested matrix of contrasts.
The matrix of contrasts with appropriate rownames is returned.
Frank Bretz <bretz@ifgb.uni-hannover.de> and
Torsten Hothorn <Torsten.Hothorn@rzmail.uni-erlangen.de>
Frank Bretz, Alan Genz and Ludwig A. Hothorn (2001), On the numerical availability of multiple comparison procedures. Biometrical Journal, 43(5), 645–656.
n <- c(10,20,30,40)
a <- 2
b <- 3
names(n) <- paste("group", 1:4, sep="")
contrMat(n) # Dunnett is default
contrMat(n, base=2) # use second level as baseline
contr.Dunnett(names(n)) # it Moore-Penrose Inverse
contrMat(n, type="Tukey")
contrMat(n, type="Sequen")
contrMat(n, type="AVE")
contrMat(n, type="Changepoint")
contrMat(n, type="Williams")
contrMat(n, type="Marcus")
contrMat(n, type="McDermott")
contrMat(n, type="Tetrade", nlevel=c(a,b))