Since 1993, our CBC software for Choice-Based Conjoint has been used successfully in thousands of studies. After years of listening to our customer's research needs and by paying attention to outside experts, we recently created the Advanced Design Module for CBC. Industry experts have commented that our CBC software worked well for the kinds of studies where all attributes freely combine with one another. But they also pointed out that some research requires "alternative-specific" designs, for which our CBC package was not appropriate.
Alternative-specific designs let you customize the list of attributes or attribute levels that apply to each alternative (product concept). Consider the following choice task:
|If you lived one mile from work, how would you choose to get there?|
Arrives every 20 min.
Costs 75 cents per one-way trip
Parking lot fee: $8.00
|Bicycle||None: I'd choose another way to get to work|
Note that the attributes that apply to buses (how often it arrives and cost per one-way trip) do not apply to cars or bicycles. The parking lot fee for cars doesn't apply to buses or bicycles. Also note that a bicycle doesn't have other attributes to further describe it. Bicycle is a "constant alternative" in addition to the constant "None" alternative.
In general, the base CBC system could not handle alternative-specific designs (although you could use alternative-specific prices with conditional pricing). Alternative-specific designs can solve situations in which it seems that specifying multiple prohibitions is the only way to make valid product combinations. The Advanced Design Module helps you avoid the detrimental conditional dependencies caused by specifying too many prohibitions between pairs of attributes.
In addition to classic transportation studies, there are many situations in which alternative-specific designs may be useful. In pharmaceutical research, the attributes that apply to one drug treatment may not necessarily apply to other treatments. In technology markets, some attributes that describe palmtops may not necessarily apply to laptops, but we may want respondents to make decisions between palmtops and laptops.
Alternative-specific designs can lead to long attribute lists (even though each alternative may involve just a few relevant attributes). For that reason, the Advanced Design Module permits CBC studies with up to 30 attributes. We still caution that conjoint studies should probably display around six or fewer attributes for any one alternative.
The Advanced Design Module also lets researchers conduct "partial profile" choice studies. Those of you who have used our ACA (Adaptive Conjoint Analysis) system are familiar with the idea of partial profiles: showing just a subset of the attributes in any one conjoint question.
With our implementation of partial profile choice, you can study up to 30 total attributes, but only display a handful at a time in any one choice task. Unlike ACA, our partial profile choice method doesn't involve an adaptive algorithm; it randomly cycles across all attributes to create a balanced and efficient design.
The user can also specify that some attributes should be displayed in every task. For example, brand and price might be included in each task while other attributes rotate in and out of the tasks. Graphics and multimedia elements can also be included in partial-profile questionnaires.
Partial-profile choice is a relatively new technique that has shown promise. Users may naturally ask whether ACA or partial-profile choice is better for studies involving many attributes. We don't know the answer, but expect that it depends upon the situation. We invite you to design carefully controlled studies to investigate those issues for yourself, and of course to share the findings if you can. You can compute individual-level utilities from partial-profile choice studies using our CBC/HB module. However, we expect that those utilities will contain more noise at the individual-level than ACA utilities which have benefitted from a customized design, ratings-based data and stabilizing priors. On the other hand, it is argued that CBC studies present a more realistic task than other conjoint methods like ACA, so the debate is certainly alive and interesting.
Please call us if you would like to order the Advanced Design Module. For those who already own CBC v2, the price is $2,000 for a Category I license. As with our other software, it comes with a 60-day money-back guarantee.