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Community Trekker

## Can you augment this mixture design?

I have 4 mixtures.  One mixture is a constant at 0.20.  I used the mixture sum option to set ingredients 1-3 to equal 0.8.

Could you augment this design by changing the constant mixture to a variable and eliminating the mixture sum advanced option?

I have attached this example DOE.

1 ACCEPTED SOLUTION

Accepted Solutions
Staff

## Re: Can you augment this mixture design?

I tried it in 11.2 and 11.2.1, and I'm still able to get it to work. Based on your screenshots, is it possible that the values are all still listed at 0.2 for X4?

If you do the change to 0.201, it's just to get Augment to recognize it as not a constant, and you can change it back afterwards. If you go forward with it as the continuous instead of mixture, it's likely not going to recognize to obey the mixture constraint.

5 REPLIES 5
Staff

## Re: Can you augment this mixture design?

You're on the right track - this one is tricky because we're dealing with both mixtures and a constant. We've made it possible to convert continuous/categorical constants, but ensuring it recognizes the mixture takes a bit of work. I'll write this out in more detail in case anyone else ever is looking to solve the same problem. I was able to get this to work in 12.1:

1) Change the "Design Role" column property of X4 (constant) to mixture.

2) You need to make sure Augment doesn't still recognize X4 as a constant based on it's values - you can change this manually within the platform for continuous/categorical, but it won't work for this mixture case. I simply changed the last row of the constant value to .201. You could also add a "first" augmented row filled in with reasonable values, if you prefer that route.

3) Choose Augment Design - X4 should now show up as a mixture.

4) From the red triangle, select Advanced Options -> Mixture Sum, and change this to 1.

5) change the range on X4 from 0 to 1 (or 0 to 0.4 in this case).

6) Select the Augment button.

7) Make sure to add the main effect for X4 and any other interactions you may want.

8) Choose your new run size, and then Make Design.

Hope that works for you!

Ryan

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Community Trekker

## Re: Can you augment this mixture design?

I don't have JMP12.1 yet, so this is what I'm seeing in JMP11.2:

After changing the design role to mixture and setting up the mixtures for the augment design, X4 is still a constant.

But, if I select to the left of X4, I am able to "Add Level", in which it automatically selects 1.2.  Now I can manually change this value and continue on with adding all 2-way interactions.

Staff

## Re: Can you augment this mixture design?

I tried it in 11.2 and 11.2.1, and I'm still able to get it to work. Based on your screenshots, is it possible that the values are all still listed at 0.2 for X4?

If you do the change to 0.201, it's just to get Augment to recognize it as not a constant, and you can change it back afterwards. If you go forward with it as the continuous instead of mixture, it's likely not going to recognize to obey the mixture constraint.

Community Trekker

## Re: Can you augment this mixture design?

Yes, I see that I didn't have to select "Add Level".  JMP automatically split the constant value into two boxes of 0.2 levels.  And I did remember to change the auto sum to recognize the new value.  Thank you for your help.

Staff