Michiel,
Great! I'll give that a go. One last question: when using constraints and pivoting in this way, how would I handle cases where a subject who has no copay enters their reference value as $0, or a subject who has strong dislike for their current facility rates it 0 stars? In the pivot design, these would then take on values less than 1, assuming x.piv[-25%,0,25%] and x.piv[-1,0,1] respectively. Would I create separate designs where each is fixed to 0, and change the pivot levels to x.piv[0%,25%,50%] and x.piv[0,1,2]?
Thank you so much for all the help, I really appreciate it.
Jamie