What is 'None Utility' from ACBC / HB estimation ?

Question

Hello,

I am facing difficulty to understand 'None' utility in excel hb report as a result of ACBC/HB estimation, though there is not 'none' level of any attributes in my study.

Q1. what is 'none utility'?
From an answer for similar question to mine, it says that "The none utility (the "not a possibility" category from the Screener section) is estimated as a part-worth utility parameter during the utility estimation."

based on the above, is 'none utility' an estimated utility of 'not a possibility'?  

Q2.
if 'none utility is an estimated utility of 'not a possibility, then
'None utility' can be considered as an intercept(a.k.a constant) for estimating utilities for other levels for each respondent?

it would be grateful for answering my questions.
 
regards,

Answer 1

Indeed, the "None" utility is the utility of the "not a possibility" choice from the Screener section of ACBC.  So, it's not really a "None" in the traditional sense, but a measure of threshold of acceptability (which indeed is a related concept).  

ACBC's None utility is therefore an intercept utility (threshold utility) representing some boundary of acceptability.  And, the utilities of the other attribute levels have been estimated for maximum likelihood fit relative to the "None" threshold.