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What is the difference between ASD and setting a prohibition level 0?

For some designs we are testing with partial profile CBC, we want to include some prohibitions with levels and attributes.  Within the PP console, we do not see where to set up ASD but in the prohibitions, we can set one up as Level=0 which seems to do basically the same thing - not allowing any level of that attribute to show up with a level of another - within a profile to make that clear.

I realize that ASD is a more efficient design than prohibitions, but how is Level=0 different and are we just missing how to assign ASD within PP?
asked Apr 11, 2018 by stevetlg.com Bronze (550 points)

1 Answer

+1 vote
Best answer
For "Partial-Profile" designs, our software does not formally support the idea of have partial-profile & alternative-specific designs (at the same time).  Some people have been able to "fool" our software into doing this, but please be careful as you may get unexpected and wrong experimental designs.  You would need to check each design version carefully to make sure that it produced what you were expecting in terms of valid product combinations.  And, you should check the "test design" report to make sure all the standard errors for simulated (robotic) respondents were reasonably small to imply good precision (0.10 or less for alternative-specific attributes; and 0.05 or less for generic attributes).

As you indicate, creating standard prohibitions to impose alternative-specific designs is typically much less efficient than doing the alternative-specific design approach.  Often, using standard prohibitions to impose alternative-specific designs leads to so much multicolinearity in the experimental design as to make the data unusable.
answered Apr 11, 2018 by Bryan Orme Platinum Sawtooth Software, Inc. (198,315 points)
selected Apr 12, 2018 by stevetlg.com