2 constraints in custom DOE where the sum of two factors should be below 8 or greater than 18 hours

[#1]

Hi,

I would like to run a custom DOE with 5 factors. 2 factors are related to time and due to work hours I have to ensure that the sum of those two factors either are below 8 hours OR greater than 18 hours. The first factor has 0.3 h as low level and 6 h as high whereas the second has 1 h and 20 h. The script below does not work, perhaps because there is an AND hidden...? thanks in advance

DOE(
	Custom Design,
	{Add Response( Maximize, "Y", ., ., . ),
	Add Factor( Continuous, 0.3, 6, "Time 1", 0 ),
	Add Factor( Continuous, 1, 20, "Time 2", 0 ), Set Random Seed( 979298838 ),
	Add Constraint( [1 1 8, -1 -1 -18] ), Add Term( {1, 0} ), Add Term( {1, 1} ),
	Add Term( {2, 1} ), Add Term( {1, 2} ), Add Term( {1, 1}, {2, 1} ),
	Add Term( {2, 2} ), Set Sample Size( 12 ), Optimality Criterion( 2 ),
	Simulate Responses( 0 ), Save X Matrix( 0 )}
);

[#2 · Accepted solution]

Hi,

Try using a disallowed combinations constraint instead of linear inequality constraints.  I believe the following script may give you the design you want.

DOE(
	Custom Design,
	{Add Response( Maximize, "Y", ., ., . ),
	Add Factor( Continuous, 0.3, 6, "Time 1", 0 ),
	Add Factor( Continuous, 1, 20, "Time 2", 0 ), Set Random Seed( 979298838 ),
	Add Term( {1, 0} ), Add Term( {1, 1} ),
	Add Term( {2, 1} ), Add Term( {1, 2} ), Add Term( {1, 1}, {2, 1} ),
	Add Term( {2, 2} ), Set Sample Size( 12 ),
	Disallowed Combinations( Time 1 + Time 2 >= 8 & Time 1 + Time 2 <= 18 ),
	 Optimality Criterion( 2 ),
	Simulate Responses( 0 ), Save X Matrix( 0 )}
);

Laura

[#3]

Thanks Laura, it works fine. Appreciate!