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Can the number of items shown vary from task to task within the same Maxdiff exercise?

I was going through the research paper "Anchored Scaling in MaxDiff
Using Dual Response" and over there it is recommended to add a dummy anchor item (not in the survey but in the design matrix) in some cases while not in the others. This would hence result in a series of tasks with varying number of items. How do we tackle this in practice?
asked May 9, 2014 by Aritra Kanjilal

1 Answer

0 votes
Our MaxDiff software needs to have the number of items the same across all choice tasks.  What the paper may be referring to is the idea that if you enter an anchor item within the list of items (such as a "status quo" item or an item conveying a specific dollar value "$50 instant rebate") that this item will appear in some tasks while not appear in others.  The total number of items per task is the same, just the anchor sometimes is included in the task and sometimes not (like any other item in the design).
answered May 9, 2014 by Bryan Orme Platinum Sawtooth Software, Inc. (132,290 points)
Oh, but upon re-reading your question, it occurs to me that you maybe are referring to the coding of the choice tasks for submitting to CBC/HB software for utility estimation.  If you follow the examples in the paper, you would be formatting the results in a .CSV file or .CHO file for submitting to CBC/HB estimation.  Indeed, CBC/HB accepts choice tasks with differing numbers of concepts per choice task.  It's very flexible that way.
Hey...thanks a lot Bryan!! :) It's good to know that CBC/HB accepts choice tasks with differing numbers of concepts per choice task. We will give this approach a try and reach out to you in case of any query. Have a great day!!