The Split Plot on a RCB
- Main experimental subjects of a RCB are divided further into
additional independent units (subplots) to which another set of treatments are randomly assigned.
- Main treatments are assigned at random within blocks of adjacent subjects, each treatment once per
- The number of blocks is the number of replications.
- Any main treatment can be adjacent to any other treatment, but not to the same treatment within the block.
Different colors represent different treatments; each vertical row represents a block. Top colors represent
assignment of main effects or treatments; bottom colors subplot treatments. There are 4 blocks (I-IV) each of 3 main treatments (A-C) divided into 3 further treatments (a-c).
Block-I Block-II Block-III Block-IV
Aa Ab Ac Bc Bb Ba Ab Ac Aa Ca Cc Cb
Cc Ca Cb Ab Ac Aa Bc Ba Bb Aa Ac Ab
Bb Bc Ba Cb Ca Cc Cc Ca Cb Ba Bb Bc
ANOVA table format:
|Error-main plots (Em)
|Subplots X Treatments (SxT)
|awhere t=number of main treatments, b=number of blocks and s=number of subplots.|
Sample ANOVA table:
|Subplots X Treatments
|aF test with 3,6 degrees of freedom at P=0.05 is 4.76|
bF test with 2,6 degrees of freedom at P=0.05 is 5.14
cF test with 2,18 degrees of freedom at P=0.05 is 3.55
dF test with 4,18 degrees of freedom at P=0.05 is 2.93
Sample SAS GLM statements:
CLASS BLOCKS TREATS SUBPLOTS;
MODEL WHATEVER = BLOCKS TREATS TREATS*BLOCKS SUBPLOTS
TEST H = BLOCKS TREATS E = TREATS*BLOCKS;
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Thursday, August 17, 2000