cochran.factorial: Factorial experiment in beans

Description Usage Format Details Source Examples

Description

Factorial experiment in beans

Usage

1
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.

Source

Cochran, W.G. and Cox, G.M. (1957), Experimental Designs, 2nd ed., Wiley and Sons, New York, p. 160.

Examples

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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")
}

agridat documentation built on May 2, 2019, 4:01 p.m.