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Impact of attribute merging


Thanks a lot for a prompt reply. In our case, one of the attributes is pretty lenghty. Merging it with the other one would create 50+ levels.

1. Wouldn't that introduce a lot of imbalance in the design?

2. Should there be a limit of e.g. 20 levels for the "merged" meta-attribute?

3. How would such merging impact relationships between original attribute levels? We'll be probably left only with the "interaction" components, but no main effect estimates.
To use your example of 3x3 + constraints=>8, will we still retain any info about level #1 of Attribute A, knowing (but not sharing it with CBC HB), that it is standing behing levels  levels #1, #4 and #7 of the meta-attribute? If we lose the main effect estimates, is there a way to retrieve them from the 8 individual levels "post-hoc"?
asked Apr 8, 2020 by Piotr

1 Answer

0 votes
Hi Piotr,

I assume you're talking about the merged rows feature of CBC?

Let me clarify the way that merged rows works and maybe that will answer your questions. The merged rows feature in CBC is strictly a display feature. In other words, The "merging" of the attributes happens after the design has already been generated. So in the designer, as well as the analysis tools, will still treat all of your attributes as individual attributes even though the respondent saw them as if they were all combined into one.

So if you have attributes A, B, and C with all of their individual levels, perhaps they all represent different levels of different features of a product, you can merge those levels together and label the new merged row as "Features". When you generate your design, the designer will still say that concept one should have attribute A level 1, attribute B level 3, and attribute C level 7. Then when the HTML is generated, there's code that sees the rule you have in place to merge Attributes A, B, and C so what the respondent sees is an "attribute" called Features that list A-1, B-3, and C-7 in that product. Then when you go to HB and the simulator, those tools don't know how the respondent saw those levels (as a merged row or as an individual row), they just know what the design was for that task and the concepts  that were and were not chosen. So Merging rows is strictly a display feature for the respondent facing part of CBC.
answered Apr 8, 2020 by Lance Adamson Bronze Sawtooth Software, Inc. (1,875 points)

Thank you for a prompt reply

My intention was to "ask related question"  to query https://sawtoothsoftware.com/forum/24947/how-to-set-cbc-hb-not-compute-utilities-for-prohibited-pairs?show=24955#a24955.

Specifically, by 'merging' I meant attribute level merging as a correct way to process attributes with interactions.

Kindly revert to the other thread and provide your consultancy here

THank you