choice-metrics.com

I am doing a "design within a design" for an overlapping (partial profile) study. I have 7 attributes, each with 4 levels, but only want to let 4 vary at a time. I want to hold 3 constant in any choice task. (I will be running a separate design for the 4 attribute combinations.)

So, my first step is to craft an orthogonal (or probably efficient given constraints) set to determine what to hold constant. Combinatorially, there are 7 choose 4, or 35 ways of holding the 3 constant. I would like to reduce this with help from NGene. I'm a bit stuck on the programming as the constraint is down rows not across columns. Ideas? Thanks, Derek

Indeed, Ngene cannot handle constraints across columns, so I think there is no easy way of doing this at this stage.