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How to calculate ZCD including Interactions?

Hi there,

on the forum I read, that there is a different approach to calculate the ZCD (from beta draws) when interactions are included.

(https://www.sawtoothsoftware.com/forum/6140/is-there-a-formula-for-calculating-the-zero-centered-diffs?show=6140#q6140)

What are the steps I have to take in this regard?

Thanks very much for your support.

Best,
Chris
asked Jul 5 by Chris Berlin Bronze (570 points)

1 Answer

+1 vote
Chris,

We take an easy approach when computing Zero-Centered Diffs involving either interaction terms or the None utility.  We ignore the interaction terms and the None utility when finding the multiplier for each respondent (such that the resulting main effect utilities have an average range of 100 utiles for each respondent).  Whatever the multiplier we figure based on the main effects for each individual, we apply that multiplier as well to the None utility and the interaction effects.
answered Jul 5 by Bryan Orme Platinum Sawtooth Software, Inc. (164,490 points)
Ok, thanks!
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