Constant Sum

Constant Sum is a survey scale that asks respondents to allocate a sum of money, time, or points across multiple items, adding to 100 (or 100% of a total value). “Please allocate 100 points among the following five items in terms of their importance to you when selecting a new car” would be a proper example of this survey scale. Note that some items may be given zero points (reflecting that they have no value to a respondent). This scale collects ratio data, though many researchers treat it as ordinal data. Unlike a rank order question, a constant sum question reveals the “distance” between items (for example, the researcher may find that one attribute is not just more important than another but twice as important). This scale type is considered more cognitively difficult for survey respondents and is used cautiously. See also: Market Research Questionnaires Over-Rely on Rating Scales