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Including Repeats in DoE using Minitab

Jafri

Involved In Discussions
#1
Minitab explains the difference between repeats and replicates.
It also explains how to add replicates to a DoE, which is Stat -> DoE -> Modify Design... (and select "Replicate design" from the list that appears).

But I cannot find anywhere in Minitab help how to add repeats in DoE.
Can anyone please help?

The best I can think of is to add replicates to design, but then enter the values we got with repeat runs.
 

Miner

Forum Moderator
Staff member
Admin
#2
Enter repeats as columns. Therefore, 6 repeats means 6 columns of data. Then run Pre-process Response for Analyze Variability to calculate the means and standard deviations of the repeats.
 

Jafri

Involved In Discussions
#3
Thanks.
So in the end, I should only enter one value (the mean value) for each run. And this is what Minitab will analyze.

If so, then I can calculate means of the 4 repeats separately, such as in Excel spreadsheet; and then enter this value in Minitab for analysis.

Is this correct?
 

Jafri

Involved In Discussions
#4
One problem I have in using "Pre-process Response for Analyze Variability", is that it is used to analyze variability in the design.
But my aim is to analyze means, so I want to use "Analyze Factorial Design" option.
 

Jafri

Involved In Discussions
#5
I think I have the answer.

Analyze location effects and dispersion effects - Minitab
So do Stat > DOE > Factorial > Pre-Process Responses for Analyze Variability, and also store the means as well, which Minitab shows as optional.
Then use this mean as the response in Stat > DOE > Factorial > Analyze Factorial Design.

In other words, we may also calculate means of repeat data separately in an Excel worksheet, and use it for "Analyze Factorial Design".
 

Miner

Forum Moderator
Staff member
Admin
#6
There are a number of ways you can do this. You can definitely calculate the means outside of Minitab and paste them in. You can enter the raw values in columns and use Row Statistics to calculate the means, and you can use Pre-process... and still Analyze Factorial Design on the means column.
 
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