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How do you get single level attributes in an ACBC?

We are doing a study using ACBC and for some of our attributes we only have one level (as we only want respondents to be shown one option when this attribute is shown ).

We are using alternative specific design as for each attribute there are three different payment options that have varying levels and this is based on the payment option that is shown in a "primary attribute".

Is there anyway we can get one payment e.g. £0 to be shown every time the payment option is shown in the "primary attribute"?
asked Dec 13, 2017 by Lucy D

1 Answer

0 votes
Go ahead and create an attribute with two levels (both duplicate levels).  Then, during the utility estimation process, turn this attribute to "Excluded" so that no utility is estimated for this attribute.

I'm assuming you are using an alternative-specific design where this attribute with just a single level is always associated with a level (or levels) of a different, primary triggering attribute.  In that case, the utility of the one-level attribute (which you are excluding from estimation) will be captured as part of the total utility of the level or levels of the primary (triggering) attribute.
answered Dec 13, 2017 by Bryan Orme Platinum Sawtooth Software, Inc. (140,065 points)
Yes that makes sense. As for this attribute the same text needs to be shown for both levels, sawtooth now gives me this error:

Error: ACBC Exercise 'ACBC' - The text for attribute 7 level 2 is not unique.

Is there anything I can do about this?

Yes that is how I am using the alternative-specific design so that is great news.

I also read somewhere that rather than using the alternative-specific design, that there might be code you can put in a constructed list for an attribute that uses the level shown in another attribute (a primary attribute like above) and depending on this will show different levels from a predefined list?
It's very easy to trick the software into using a list for ACBC where the two levels look exactly the same to respondents.  Just put two space characters between two of the words for one of the (duplicate) versions of the list element.  Browsers ignore two spaces and insert one space instead to show respondents.  But, to the Lighthouse Studio software, the two versions of the text will not appear to be a perfect match, to it will avoid the error message.
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