Blocking problem 6.20 in two
Incomplete Blocks and…….
Reality strikes…..
Block on a term which is likely insignificant.
• A*B*C*D is the least likely (we hope) to be
insignificant so let’s use that to “block” on.
• How do we do that? Use the contrast for that
interaction to divide the treatment
combinations into two groups of size 8.
• Why? A*B*C*D will then be completely
confounded with Block.
Block 1
Block 2
New ANOVA with Block
Main Effects
Laser Power*Cell Size
What would happen if your budget were
suddenly cut (yeah, it happens a lot) ….
• Probably run a ½ Fraction of the experiment.
• Which half?
• Either Block 1 or Block 2.
What can be estimated?
Answer: Only Main Effects.
Question: There must be confounding so how do
we know what is confounded with what?
Answer: The All Powerful Identity Equation!!!!
I=A*B*C*D
A=B*C*D
A*B=C*D, etc.
What does Block 1 data alone tell us?
What does Block 2 data alone tell us?