What is a constant sum?

A constant sum question is a useful way of understanding how much value customers place on specific product features. A typical constant sum question will ask respondents to allocate 100 ‘points’ across each feature with the highest number being allocated to the most important feature and the lowest to the least important.

How to add a constant sum question to my experiment?

To add a constant sum question to your experiment, click on the “Additional Questions” tab, click the “Add Question” button at the bottom of the screen and select “Constant sum” from the table of options.

How does a constant sum output look like?

Below is an example output of a constant sum output. The graph shows the average number of points allocated to each option across all respondents.

An example of constant sum output data

When should I use a constant sum question?

You should use a constant sum question when:

  • You have a list of features (not more than 5) to prioritise
  • When the features are conceptually easy to understand
  • It is not the main objective of your study

If the main objective of your study is to identify and prioritise features of your product, we would recommend to use Generic Conjoint instead.