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Draws for the part-worth you want to compute the HPD

Thank you so much Kenneth for your help on HPD... That's really helpful!!

I just want to be sure on "Draws for the part-worth you want to compute the HPD".  Here, I am working on CBC design &  could see 3 measures (Individual Utilities (ZC Diffs), Individual Utilities (Raw), alpha draws). Which one do I need to consider for my HPD calculation?? From Sawtooth, I could see one summary sheet with Average Utility score along with Standard Deviation and these are based on "Individual Utilities (ZC Diffs)". So I was assuming to use "Individual Utilities (ZC Diffs)" for my HPD calculation. Kindly suggest.
(From Sawtooth support, I got a suggestion to use "alpha draws", but this is available for each of the iteration (instead of Respondent/record)... So I am confused)
related to an answer for: Highest Posterior Density(HPD)
asked Dec 11, 2017 by Narasimha Rao Tadekoru

1 Answer

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Best answer
Alpha draws is the best overall measure of the model fit for your part-worths. The individual raw utilities should be very similar, but the alpha draws are what you will want for HPD calculations.

 It's true that the alpha draws do not reflect the individuals in your model. Instead, they are the 'upper level' part worths in your model. So if you're looking for aggregate effects, that is where to find them, and that's where to build your HPDs.

Best,
Kenneth
answered Dec 12, 2017 by Kenneth Fairchild Bronze Sawtooth Software, Inc. (3,495 points)
That helps, Thank you Kenneth! I will try to see HPD interval for 2 or 3 example studies by using both raw utilities and alpha draws and then will see the applicability :) Thanks again for all your time and support!!
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