Illume calculations are algorithms that are run within a survey, and persist within the survey data set.  Calculations are run on every page, i.e. every time the respondent clicks the Next button, all calculations are re-run.  A survey may contain multiple calculations, and calculations can include other calculations.  Calculations are processed in the order that they appear in the calculations editor, which is particularly relevant when calculations are based on the results of other calculations.

There are a number of valuable uses for calculations.  Calculations can be used to do the following (this list is not all inclusive):

  1. Create scores
  2. Grab the current date, time, year, or other local information from the respondent’s device
  3. Calculate new variables from survey variables, e.g. calculating a participant’s age from their entered Date of Birth
  4. Output text.  For example, a survey may ask for the respondent’s child’s gender.  Throughout the survey you may want to include questions such as “how old was he/she when he/she learned to walk”.  Rather than saying “he/she”, you can create a calculation that outputs the word “he” if Gender=male, and outputs “she” if Gender equals female.
  5. Set the value of a Preload/Hidden variable or other survey variable