blanket type, a factor at four levels: b0, b1,
b2, and b3.
minutes
response variable: recovery time after a surgical
procedure.
Details
A company developed specialized heating blankets designed to help the
body heat following a surgical procedure. Four types of blankets
were tried on surgical patients with the aim of comparing the
recovery time of patients. One of the blanket was a standard blanket
that had been in use already in various hospitals.
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., page 66.
Examples
### set up one-way ANOVA
amod <- aov(minutes ~ blanket, data = recovery)
### set up multiple comparisons: one-sided Dunnett contrasts
rht <- glht(amod, linfct = mcp(blanket = "Dunnett"),
alternative = "less")
### cf. Westfall et al. (1999, p. 80)
confint(rht, level = 0.9)
### the same
rht <- glht(amod, linfct = mcp(blanket = c("b1 - b0 >= 0",
"b2 - b0 >= 0",
"b3 - b0 >= 0")))
confint(rht, level = 0.9)