Randomization on Minitab
The following is easier than the steps in Section 3.2:
1. Start as in Step 1 on p. 34: Enter r1 1's. r2 2's,
etc. into a column. You can do this by hand. If your design is balanced,
you can use Set Patterned Data (Calc menu). For example, if you have three
groups of 4 each, specify to start at 1, end at 3, with increment 1, and
then enter 4 in "Repeat each value".
2. To randomize, choose Random Data from the Calc menu, then Sample
from Columns. Enter the total number of observations desired (n = sum of
the ri's) in "Sample ____ rows", enter the column you just made
after "from," and the column where you want the randomized numbers in "Store
samples in." Sample output (using 2,2, and 3 as treatment sizes):
| obs |
treat |
randtr |
| 1 |
1 |
1 |
| 2 |
1 |
3 |
| 3 |
2 |
1 |
| 4 |
2 |
3 |
| 5 |
3 |
3 |
| 6 |
3 |
2 |
| 7 |
3 |
2 |
(I have added a column "obs" for convenience.) This says assign experimental
units 1 and 3 (first column) to treatment 1 (last column), units 6 and 7
to treatment 2, and units 2, 4, and 5 to treatment 3. (Note that the second
column was just an intermediate step.)