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Binary Choice Task With a Fixed Alternative


I am trying to replicate a study. It is an older study (2006) and in the study the respondents have to make a transport mode choice. The choice is binary, either public transport or car. In the original study the choice had car as a constant alternative, car, and a changing alternative public transport.

This is an alternative specific design. however I am wondering how I can hold the car constant (with different levels) and vary the PT component (bus, tram, train)? In the original design it had this constant car structure.

Does anyone have any suggestions?

asked Oct 30, 2017 by Jasha Bowe Bronze (1,745 points)

1 Answer

0 votes
You could potentially stitch two designs together.  Our CVA software I believe is a little more efficient at this, but you could do it with a CBC exercise and create a design with one concept versus a none (repeated two times to create the car profiles and the public transport profiles).  Then export them to Excel, copy and paste together, then import into a new study that shows 2 concepts at a time.

The other way I can think of it would be to just use prohibitions such that you could never show two public transport options against each other in a task.  This would require the Advanced Design Module license for CBC to allow you to specify cross-concept prohibitions.

I'm not sure which would result in a better design off the top of my head.   Maybe the prohibitions approach since the designer would be considering the two-way balance between car and public transport alt-specific attributes?
answered Oct 30, 2017 by Brian McEwan Gold Sawtooth Software, Inc. (38,970 points)
Coss concept prohibitions