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ZCD just for easier interpretation or aggregation of individual PWU?

Dear all,

could you please clarify, if the raw utilities are just rescaled (zero-centered diffs) to enable an easier interpretation or is this also a necessary step to average the individual utilties to the aggregated utilties reported in the utility report of ACBC/HB studies?


asked Apr 16, 2019 by Chris Berlin Bronze (570 points)

1 Answer

+1 vote
Best answer

The ZCD transformation is partially for easier interpretation, but also it is a way of making utilities more comparable across respondents.  In a logit model, respondents who choose more consistently tend to have utilities with larger absolute values while respondents who answer less consistently tend to have utilities that have smaller absolute values.  ZCD attempts to remove as much of this difference magnitudes owing to differences in amounts of response error as possible.  

It is not a necessary step in averaging utilities as averaging the raw utilities would also be viable.
answered Apr 16, 2019 by Keith Chrzan Platinum Sawtooth Software, Inc. (103,225 points)
selected Apr 17, 2019 by Chris Berlin