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Dual Response CBC

We are trying to design a CBC exercise where we will show multiple concepts in each screen.  However, instead of choosing one concepts, the respondents could choose version A or B for each concept.  The two versions have different price points.  We wanted to see whether the prices and price gaps for the two versions would impact a respondents' choice of the concepts.

Any suggestion how best to accomplish this?  Thanks!
asked May 12, 2014 by HongHu Bronze (835 points)
Why would the choice not be reduced to that between the cheapest of each concept? Are you presenting prices in such a way as variant A and B within each concept can not be easily compared?
Basically the variety is about quantity.  For example, a single license vs. a family license.  So A is cheaper and B is more expensive.

1 Answer

+1 vote
Thanks for the clarification.
I would generate the 'A' concepts using the standard tools.
Then in Excel double up the concepts for each task and randomly tweak the 'B' concepts (every other task when ordered - identical to A except for the necessary variation).
In the software add in the attribute, for the 'random variation' and then import the new design into the software (so you now have each concept with two variants and an attribute that identifies the variant).
Does this make sense? It depends on my understanding of your original query.
answered May 14, 2014 by Andrew Reynolds Bronze (1,140 points)
Yes, this makes great sense.  What is your opinion on these two options:
1. Exactly as you said, generate a design that has, say, 3 concepts each task, 6 tasks each respondent.  Then double the design and add the randomized variants attribute, so now each version has 3 concepts each task, 12 tasks each respondent.
2.  Generate a design that has, say, 3 concepts each task, 6 tasks each respondent.  Then double the concepts for each task.  And add a variants attribute so that the original concepts would have a level 1 and the doubled concepts have a level 2.  Therefore there are 6 concepts each task, and 6 tasks each respondent.
As you are effectively doubling the number of concepts I would see if I could get away with two initial concepts per task - doubling up to four. Then aim for 12 tasks. However, this would need the Advanced test to investigate the standard errors. It depends though on the number of other attributes/levels in the design. If you are lucky enough to have few, or can present more in a simplified way, then the cognitive burden is easier and you can aim for more concepts and fewer tasks. Peoples heuristics do change as the number of tasks increases. Which is more realistic (earlier versus later answers) is debatable - however - fewer tasks is likely to be more consistent!
Yes, totally agree.  Thanks a lot!
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