cochran.factorial {agridat} | R Documentation |
Factorial experiment in beans
data("cochran.factorial")
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)
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.
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") }