An oft-cited RCBD example is an agricultural experiment which evaluates the effect of levels of of soil K\(_2\)O (potash) on the breaking strength of cotton fibers (Cochran and Cox 1957). Five levels of K\(_2\)O were used in the soil subplots ( 36, 54, 72, 108, and 144 lbs per acre) and a single sample of cotton was taken from each of five subplot. The experiment had three blocks, and each of the K\(_2\)O treatments was randomly assigned to the five subplots within each block.
data(potash)
A data frame with 15 observations on the following 3 variables.
treatment
a factor with levels 36
54
72
108
144
block
a factor with levels 1
2
3
strength
a numeric vector