Factorial experiment in beans
Factorial experiment in beans
data("cochran.factorial")A data frame with 32 observations on the following 4 variables.
reprep factor
blockblock factor
trttreatment factor, 16 levels
yieldyield (pounds)
Conducted by Rothamsted Experiment Station in 1936. The treatments are listed below.
d = dung: None, 10 tons/acre.
n = nitrochalk: None, 0.4 hundredweight nitrogen per acre.
p = Superphosphate: None, 0.6 hundredweight per acre
k = muriate of potash: None, 1 hundredweight K20 per acres.
The response variable is the yield of beans.
Cochran, W.G. and Cox, G.M. (1957), Experimental Designs, 2nd ed., Wiley and Sons, New York, p. 160.
## Not run:
library(agridat)
data(cochran.factorial)
dat <- cochran.factorial
# Split treatment into individual factors
dat <- transform(dat,
d = -1 + 2 * grepl('d',trt),
n = -1 + 2 * grepl('n',trt),
p = -1 + 2 * grepl('p',trt),
k = -1 + 2 * grepl('k',trt))
dat <- transform(dat, d=factor(d), n=factor(n), p=factor(p), k=factor(k))
# Cochran table 6.5.
m1 <- lm(yield ~ rep * block + (d+n+p+k)^3, data=dat)
anova(m1)
libs(FrF2)
aliases(m1)
MEPlot(m1, select=3:6,
main="cochran.factorial - main effects plot")
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