Randomizing the Design
main topics 

By default, Minitab randomizes the run order of the design. The ordered sequence of the factor combinations (experimental conditions) is called the run order. It is usually a good idea to randomize the run order to lessen the effects of factors that are not included in the study, particularly effects that are time-dependent.

However, there may be situations when randomization leads to an undesirable run order. For instance, in industrial applications, it may be difficult or expensive to change factor levels. Or, after factor levels have been changed, it may take a long time for the system to return to a steady state. Under these conditions, you may not want to randomize the design in order to minimize the level changes.

Every time you create a design, Minitab reserves and names C1 (StdOrder) and C2 (RunOrder) to store the standard order and run order, respectively.

·    StdOrder shows what the order of the runs in the experiment would be if the experiment was done in standard order - also called Yates' order.

·    RunOrder shows what the order of the runs in the experiment would be if the experiment was run in random order.

If you do not randomize, the run order and standard order are the same.

If you want to re-create a design with the same ordering of the runs (that is, the same design order), you can choose a base for the random data generator. Then, when you want to re-create the design, you just use the same base.