The Alfalfa data frame has 72 rows and 4 columns.
This data frame contains the following columns:
a factor with levels
Cossack,
Ladak, and
Ranger
a factor with levels
None
S1
S20
O7
a factor with levels
1
2
3
4
5
6
a numeric vector
These data are described in Snedecor and Cochran (1980) as an example of a split-plot design. The treatment structure used in the experiment was a 3\( x \)4 full factorial, with three varieties of alfalfa and four dates of third cutting in 1943. The experimental units were arranged into six blocks, each subdivided into four plots. The varieties of alfalfa (Cossac, Ladak, and Ranger) were assigned randomly to the blocks and the dates of third cutting (None, S1---September 1, S20---September 20, and O7---October 7) were randomly assigned to the plots. All four dates were used on each block.