Hi all,
I'm trying to manually resolve Cp for a simple set of data, but my results don't match the ones I get from Minitab.
Data (a is the response)
a b c
1 1 6
2 5 1
3 4 5
4 1 2
Results from Minitab for best subset

Response is a
Note: R-Sq, R-Sq (adj), and R-Sq (pred) are displayed only for models that include a
constant.

R-Sq R-Sq Mallows
Vars R-Sq (adj) (pred) Cp S b c
1 * * * 0.5 2.0854 X
1 * * * 1.0 2.2686 X
2 * * * 2.0 2.2857 X X

Any idea? I can't get a Cp of 0.5 for b...

Thanks!