agridat (version 1.16)

cochran.factorial: Factorial experiment in beans

Description

Factorial experiment in beans

Usage

data("cochran.factorial")

Format

A data frame with 32 observations on the following 4 variables.

rep

rep factor

block

block factor

trt

treatment factor, 16 levels

yield

yield (pounds)

Details

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.

Examples

# NOT RUN {
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)


if(require(FrF2)){
  aliases(m1)
  MEPlot(m1, select=3:6,
         main="cochran.factorial - main effects plot")
}

# }