Detergent Durability Data Set

Description

Detergent durability in a fractional design experiment; data set taken from Westfall et al. (1999, p. 189). Balanced incomplete block design.

Usage

data(detergent)

Format

This data frame contains the following variables

detergent

detergent at 5 levels: 1 ... 5

block

block at 10 levels: 1 ... 10

plates

Response variable: number of plates washed before the foam disappears.

Details

See Westfall et al. (1999, p. 189)

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.

Examples

data(detergent)

N <- rep(2, 5)

# BIBD: prepare the contrast matrix = all-pair comparisons for 
# the 5 levels of detergent

C <- contrMat(N, type="Tukey")

# adjusted p-values: either using the contrast matrix C
summary(simtest(plates ~ block+detergent, data=detergent, whichf="detergent",
                ttype="logical", cmatrix=C))

# or, more easily, type="Tukey"
summary(simtest(plates ~ detergent + block, data=detergent,
        whichf="detergent", type="Tukey", ttype="logical"))