Split Plot design

Let’s see if I can “make-up” an example dataset for a Split-plot design.  The classic use of this particular experimental design has been in crop science or plant agriculture.  So let’s assume we have access to a large field which we have subdivided into 8 blocks.  Four of these blocks have access to Irrigation type A and the remaining 4 blocks have access to Irrigation type B.  Within each of these blocks, we will subdivide it into 3 areas, in which we will randomly assign 1 of 3 crops to grow in each.

Let’s build the model first…  Irrigation is the Whole plot and crops are the subplot.
data crops_2012;
   input Block irrig crop Y @@;
   datalines;
1 1 1 56 1 1 2 41
1 2 1 50 1 2 2 36
1 3 1 39 1 3 2 35
2 1 1 30 2 1 2 25
2 2 1 36 2 2 2 28
2 3 1 33 2 3 2 30
3 1 1 32 3 1 2 24
3 2 1 31 3 2 2 27
3 3 1 15 3 3 2 19
4 1 1 30 4 1 2 25
4 2 1 35 4 2 2 30
4 3 1 17 4 3 2 18
;
Run;

Let’s create the Proc GLM coding and then the Proc MIXED coding

Split plot data and coding