Attributes Tab (ACBC)
List of Attributes: Each ACBC study should have a list (either pre-defined or constructed) that contains the attribute labels (one list element per attribute). Select that list using the drop-down box. If you haven't yet created that list, go to the Lists dialog. The maximum number of attributes (items) in the list is 100.
Note: if you have more than about 12 total attributes in your study, we recommend using constructed lists and previous questions to reduce the number of relevant attributes to include in the ACBC questions to no more than about 12.
List of Levels: Each ACBC study should have a list (either pre-defined or constructed) that contains the levels for each attribute (one list element per level). Select that list using the drop-down box (for Summed Price attributes, no level list is selected). If you haven't yet created that list, go to the Lists dialog. The maximum number of levels (items) in each list is 250.
For a "Summed Price" attribute, select <Summed Pricing Attribute> in the drop-down control.
Note: if you have more than about 7 total levels for an attribute in your study, we recommend using constructed lists and previous questions to reduce the number of relevant (preferred) levels to include in the ACBC questions to no more than about 7 per attribute.
Sequence Order: For the Must Haves and Unacceptable levels, ACBC needs to know how to phrase the questions and apply logic to identify irrelevant levels. To that end, we need to know whether each attribute has Sequence order. Attributes like brand and color are nominal (qualitative) in nature, and have no sequence order. Attributes like speed, weight, or quantity have sequence order. Indicate whether each attribute has None, Low to High, or High to Low sequence order. Note that Low to High refers to the numeric quantities attached to each level, not to preference, so weights of 2 kilos, 4 kilos, 6 kilos are arranged in sequence order of Low to High (irrespective of actual preference direction).
Note: for attributes without sequence order, we recommend you randomize the order of the levels to reduce order bias, by using a constructed list where the list of levels has been randomized.
Preference Order: For the Must Haves and Unacceptable levels, ACBC needs to know how to apply logic to identify unacceptable levels. For example, if I state that I need an automobile that has at least 180 horsepower, then ACBC would recognize that any levels lower than 180 can be eliminated from further consideration. Indicate whether each attribute has None, Worst to Best, or Best to Worst preference order. Note that indicating a preference order for an attribute does not constrain the resulting part-worths to reflect that order. Utility constraints may be applied later during utility estimation if desired.
Include in BYO. By default, all attributes are included in the BYO question. However, you may encounter situations in which you'd like to exclude an attribute from the BYO question. For example, consider an attribute with a priori preference order (where it is clear which level is superior) where it doesn't make sense to assign price premiums for Summed Price. In that case, it would be obvious to every respondent which level is preferred, and such a question would seem out-of-place. If you choose to drop an attribute from BYO, ACBC will supply an answer to the BYO question in the data file as if the respondent had picked the best level. But, the levels for that attribute will be represented roughly evenly in the design of the concepts seen in the later sections. For analysis, we automatically exclude the BYO information for that attribute from utility estimation (as it would bias the utilities with too much certainty regarding the preference for the preferred level). However, it may make sense to impose utility constraints for an attribute that is omitted from the BYO section.
Include in Must-Haves and Unacceptables. By default, all attributes (except in special cases, Summed Price) are potentially included in Must-Haves and Unacceptable questions. However, if for some reason you wish to prohibit an attribute from appearing in the Must-Haves and Unacceptables questions, you could specify that here. Please note that including some attributes in Must-Haves and Unacceptable questions but not including others could lead to undesirable differences in the importance of attributes (as derived from the spread of the part-worth utilities). When an attribute has an opportunity to have a level marked as a Must-Have or an Unacceptable, then the information regarding the desirability or undesirability of an attribute level is potentially quite strong.
Note: The Summed Price variable by default does not appear in Must-Haves and Unacceptables. But there is an option on the Pricing tab to enable Summed Price in Unacceptable questions.
For more information about creating attribute and level lists for ACBC projects, please see Attributes and Levels for Adaptive CBC.
