multcomp (version 0.3-8)

litter: Litter Weights Data Set

Description

Dose response of litter weights in rats; data set taken from Westfall et al. (1999, p. 109). Specific dose comparisons in a dose response experiment with two covariates.

Usage

data(litter)

source

P. H. Westfall, R. D. Tobias, D. Rom, R. D. Wolfinger, Y. Hochberg (1999). Multiple Comparisons and Multiple Tests Using the SAS System. Cary, NC: SAS Institute Inc.

Details

See Westfall et al. (1999, p. 109)

Examples

data(litter)

# define the contrast matrix, either completly
C <- matrix(c(0,0,0,0,0,0,1,1,1,.75,.384,.887,-1,0,0,.25,.37,.113,
       0,-1,0,-.25,.246,-.339,0,0,-1,-.75,-1,-.661,0,0,0,
       0,0,0,0,0,0,0,0,0), ncol=7)
# numerate the contrasts
rownames(C) <- paste("C", 1:nrow(C), sep="")

# simultaneous confidence intervals for above comparisons 
# in an ANCOVA
summary(simint(weight ~ dose + gesttime + number, data=litter,
               alternative="greater", cmatrix=C))

# or for dose only
D <- matrix(c(1,1,1,.75,.384,.887,-1,0,0,.25,.37,.113,0,-1,0,-.25,
              .246,-.339,0,0,-1,-.75,-1,-.661),ncol = 4)
rownames(D) <- paste("D", 1:nrow(D), sep="")

summary(simint(weight ~ dose + gesttime + number, data=litter,
               whichf="dose", alternative="greater", cmatrix=D))