The MSPE (the average of cell variances) can be obtained in a couple
different ways. If you have entered all your data in a single column,
you can enter another column containing a cell identifier. Suppose
you had replicated an 8-run design 5 times and the data was entered in
C1. From the Edit>Command Line Editor window in Minitab, you could enter (and
then press Submit):
set c2
You can then ask for descriptive statistics (by c2) to obtain the
cell variances. Select Stat>Basic Statistics>Store Descriptive
Statistics. Enter C1 in the Variables box, and C2 in the By
Variables box. In the Statistics menu, check Variance; Minitab will
automatically store the variances in a column. Assume the variances
are stored in C4. Back in the Edit>Command Line Editor window, type
Average C4
to obtain the MSPE.
If you have entered the reps in 5 separate columns, you can use a
row operator to obtain variances. If the reps are in columns C1-C5,
select Calc>Row Statistics. Check Standard Deviation (Minitab
does not have a Variance option), enter C1-C5 in the Input Variables
box and C6 in the Store Result In box. In the Calculator, enter
the formula: mean(c6*c6), and store the result in C7 to obtain the MSPE.
(1:8)5
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