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Best way to implement CBC chip allocation with multiple (2) None products

We are planning to do a constant sum CBC chip allocation with 3 products per exercise – 8 attributes with 2-4 levels each.
Product 1: A regular varying profile (A new concept drug we want to see which aspects are important for prescribing)
Product 2: A fixed profile that never changes (but just happens to contain levels that could appear in Product 1)(Current drug we already know the levels for)
Product 3: None option (Some other treatment)

Based on another forum response, it sounds like design-wise; we could either export the design file and fix Product 2 and reimport or just edit the HTML.  On the analysis side, am not sure what the best (easiest) way would be to generate a utility value for Product 2, which I would imagine would just be a single part-worth like for Product 3.  

We customize our own simulators, so from there it should be easy to just calculate the share across the 3 products.  So hoping we can use lighthouse to generate those utilities.

Suggestions for easiest way to generate utilities with this setup?

Thanks,  Steve
asked Jul 15, 2020 by stevetlg.com Bronze (550 points)

1 Answer

+2 votes
It's a bit of a toss up what the easiest way would be.  From a design perspective, fixed products are usually handled just as an extreme alternative-specific design where attribute 1 is Product, and then the other attributes (dosage, efficacy, price, etc.) are all set to not apply to the level that is the fixed option.  Then, I usually use a conditional display to fill in the blanks and make it look like fixed product 2 always has a "once a month pill" for that attribute.

You could also create the design in this way or without fixed product 2, export to Excel, and add in the fixed product.  My guess is the above approach would be easier because by default the design will not have fixed product 2 in the second row every single time.

Honestly I'm not sure what the "better" way of handling it for analysis would be.  The neat thing is you could probably try it out both ways.  Run it once as alternative-specific, then you could run it again with the levels actually put back in every time for the product.  I checked with someone from our consulting group and their hunch is that the alternative-specific approach would probably work better, because existing drugs tend to be well known, but their exact specifications probably not as much well known.  The alternative-specific design forces everything to kind of be "front loaded" into the product parameter, rather than spreading it out over all the levels.
answered Jul 16, 2020 by Brian McEwan Platinum Sawtooth Software, Inc. (56,045 points)
Brian, that's really helpful.  Sounds like the alternative specific approach will work best - just found out the client may want to vary a couple of the attributes for product 2 after all, so ASD makes it completely flexible.  I can adjust the design to always show product 2 in that second position, so all good there.  And then utilities will be right out of the box, no additional manipulation needed.  Just have to add in the conditional display and good to go.  Thank you!
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