Disallowed Combinations not working

[#1]

Hi,

I am trying to make disallowed combinations in my custom design.

I have a factor with two categorical levels: No ChCl and ChCl and a factor with three ChCl molar ratio (categorical): 0, 1 and 2

I want to make a Disallowed Combinations where 'No ChCl' and a molar ratio of 0 cannot be made. 

ChCl== "No ChCl" & Molar ratio ChCl== '0'

But the design still makes a combination of No ChCl and 0. What am I doing wrong?

best regards, Freja

[#2]

Dear @frejam ,

with your input I was able to make a custom design with factor contraints to make the disallowed combination.

(JMP18)

Please see enclosed table, is that what you need?

To understand what went wrong in your example, it would be quite helpful if you could share your DOE table.

BR

[#3]

Hi Georg,

I don't see that it works in your example either?

So here I applied the constrain, but I still combination where molar ratio (ML HBA) is 0 and HBA is ChCl.

What I want is that if HBA = ChCl then ML HBA should be >0, or if HBA = No ChCl then ML HBA = 0. Does that make sense? I attached my DoE table (I hope)

Best regards Freja

[#4 · Accepted solution]

Hi @frejam,

I would recommend setting the factor ML HBA as a discrete numeric with three levels instead of a 3-levels categorical factor, as the ordering between levels is taken into consideration with the discrete numeric factor type, and it does suit better your experimental design from what I see. It also facilitates the creation of the disallowed combinations constraint.

If I set up the disallowed combinations like these :

Or in a script version : 

HBA == "ChCl" & ML HBA <= 0.5 | HBA == "No HBA" & ML HBA >= 0.5

Then the generated design seems to respect the constraint you want:

Here is the script to generate the design (I assumed a model with main effects and 2-factors interactions) :

DOE(
	Custom Design,
	{Add Response( Maximize, "Y", ., ., . ),
	Add Factor( Continuous, 1, 2, "Molar ratio HBD", 0 ),
	Add Factor( Categorical, {"Oxalic acid", "Citric acid"}, "HBD", 0 ),
	Add Factor( Categorical, {"ChCl", "No HBA"}, "HBA", 0 ),
	Add Factor( Discrete Numeric, {0, 1, 2}, "ML HBA", 0 ),
	Set Random Seed( 2109323028 ), Number of Starts( 3867 ), Add Term( {1, 0} ),
	Add Term( {1, 1} ), Add Term( {2, 1} ), Add Term( {3, 1} ), Add Term( {4, 1} ),
	Add Potential Term( {4, 2} ), Add Term( {1, 1}, {2, 1} ),
	Add Term( {1, 1}, {3, 1} ), Add Term( {1, 1}, {4, 1} ),
	Add Term( {2, 1}, {3, 1} ), Add Term( {2, 1}, {4, 1} ),
	Add Term( {3, 1}, {4, 1} ), Set Sample Size( 18 ),
	Disallowed Combinations(
		HBA == "ChCl" & ML HBA <= 0.5 | HBA == "No HBA" & ML HBA >= 0.5
	), Simulate Responses( 0 ), Save X Matrix( 0 ), Make Design}
)

And you can find the datatable attached.

The analysis should be done carefully, as you might have a nested effect of "ML HBA" inside "HBA" : the level 0 for factor "ML HBA" is only accessible for the level No HBA of factor "HBA". 

Hope this answer will help you,

[#5]

Hi Victor,

Thank you so much for helping out. This was exactly the solution I needed

Best regards, Freja

[#6]

Hi again,

Can you expand on what you mean by this sentence?:

"The analysis should be done carefully, as you might have a nested effect of "ML HBA" inside "HBA" : the level 0 for factor "ML HBA" is only accessible for the level No HBA of factor "HBA". 

I can see that I get a very low score for HBA and ML HBA (<0.4) in my power analysis when I put on the constrain. Is this effect you are talking about above and any suggestions to improve this?

Sorry for all my questions - I am new in DoE design.

Best regards, Freja