ACBC HB analysis taking 15+ hours

Question

Hi

I am doing an ACBC study and doing a HB analysis. Price is a summed price in the design. For the HB analysis I used piecewise option - for this option I created 27 price increments (I know that is perhaps a lot).

I set the iterations to 50 000 for prelim and 50 000 for each respondent.

 I have 284 respondents.

The problem is that the analysis is now taking more than 15 hours - and there is still about 4 hours left. I have a simple laptop, but it is not that old (Rizen7, 20Gig Ram, SSD).

Does anyone have any suggestions on how to either reduce the time, but still keep the price intervals? Or perhaps make use of a faster computer?

I was thinking of splitting the sample into for instance regional groups or some kind a sub-sample that makes sense, and then running 4 or 5 smaller HB analysis on each sub-sample - perhaps the combined time of smaller groups will be less than this?

Thanks

Comments

Generally 284 respondents shouldn't take such a long time.  Are any network drives involved? HB is a very read/write intensive process, so if the files are local on your C drive that can slow things down dramatically.

Also if we remove the customizations and just run a "vanilla" HB model (linear price, no constraints, no interaction effects) do you still experience a very long time?

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Hi Brian,

Thanks for your reply. There are no network drives involved. All the files are local, on C:\Users\User\Documents\Sawtooth Software\Lighthouse Studio\Studies - is there an alternative to this?

I ran a HB analysis, vanilla, - it took just over 15 minutes.

I would appreciate any further advice on how to possibly speed things up a bit.

Thanks again,
Kobus

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Ok, it probably is due to the price levels then. 27 is quite a lot. I would be tempted to trim that down quite a lot and see if your utilities and simulator predictions actually change all that much.  As Bryan Orme mentioned, if the parameters violate the constraints then it has to do the tie-breaking stuff so they match the constraints and that can make things take a really long time.

Answer 1

I recommend price constraints on piecewise functions in many cases, and I suspect you're doing this.  If you use so many breakpoints along the piecewise function, our recursive tying algorithm bogs down and can take a long time.

Comments

Hi Bryan. Yes I am using constraints. Thanks for the feedback. The output I get from this is powerful. I keep the time it takes as part of my analysis planning so I'll just keep doing that. Thanks