multcomp (version 0.3-8)

contrMat: Contrast Matrices

Description

Computes contrast matrices for several multiple comparision procedures.

Usage

contrMat(n, type=c("Dunnett", "Tukey", "Sequen", "AVE", 
                   "Changepoint", "Williams", "Marcus", 
                   "McDermott", "Tetrade"), nlevel=NULL)

Arguments

n

a (possibly named) vector of sample sizes for each group.

type

type of contrast.

nlevel

number of levels of two factors (for type="Tetrade" only).

Value

• The matrix of contrasts with appropriate rownames is returned.

Details

Computes the requested matrix of contrasts.

References

Frank Bretz, Alan Genz and Ludwig A. Hothorn (2001), On the numerical availability of multiple comparison procedures. Biometrical Journal, 43(5), 645--656.

Examples

n <- c(10,20,30,40)
 a <- 2
 b <- 3
 names(n) <- paste("group", 1:4, sep="")
 contrMat(n)	# Dunnett is default
 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))