topic Re: Factor constraints in custom design in Discussions

Factor constraints in custom design

billi — Thu, 23 Jan 2020 17:06:36 GMT

I am using custom design with 3 continuous factors and I am trying to add factor constraint that X1 cannot be greater than X2. I tried using option 'Use disallowed combination filter' but it gives me setting for X1 in decimals (eg. 350.9811). Data table is attached. Is this the correct way to add this type of constraint?

Re: Factor constraints in custom design

Mark_Bailey — Thu, 23 Jan 2020 17:38:36 GMT

Use a linear constraint like this one:

Re: Factor constraints in custom design

billi — Thu, 23 Jan 2020 19:42:59 GMT

@Mark_Bailey Thank you for help. This works.

Re: Factor constraints in custom design

billi — Mon, 27 Jan 2020 15:52:26 GMT

@Mark_Bailey After I add this constraint, the design gives me run which have same values for X1 and X2 factor (shown in data table attached in run 2,3,6,10) and I want to add another constraint so that I do not have any run with same value of X1 and X2. I tried different combinations but was unable to do it. Do I need to use some other option to add the second constraint I want?

Re: Factor constraints in custom design

Mark_Bailey — Mon, 27 Jan 2020 17:04:43 GMT

Yes, you said that you needed X1 not to be greater than X2, and the constraint works.

So X2 must be greater than X1, after all? You cannot use a script to define constraints with mixture components. (Yeah, I was surprised, too.) That only leaves the linear constraint. So you must decide the amount by which X2 must exceed X2. Set the constraint with the margin on the right side of the inequality, like this:

X2 must exceed X1 by at least 0.1 proportion.

Re: Factor constraints in custom design

billi — Tue, 28 Jan 2020 13:53:33 GMT

@Mark_Bailey This works. Thank you for your help.