A derived question is a new question built by combining the answers of two or more existing survey questions. The classic example is an "Age × Gender" cell that combines a five-bucket age question with a gender question into a single 12-option question you can use as a row or column in a report.
Derived questions live alongside your other questions on the Questions tab. Once created, they behave like any other question in reporting — you can add them to a report's scope, set their role in Layout, choose calculations on the Analysis step, and recategorize their options.
You do not need to change your survey code to use derived questions; they are computed from existing responses.
When to use a derived question
Reach for a derived question when you want to:
- Report on the intersection of two screening questions (age bands × gender, region × income bracket, household composition × tenure).
- Build a custom segment from several flags without round-tripping through data prep.
- Compare a small number of meaningful combinations and drop the rest — for example, four "primary persona" combinations from a longer cartesian product.
If you instead want to compute a new value from a calculation (age from year of birth, lift between two ratings, a list of selected brands), you want a calculated or stored variable in the survey code. See Recoding and post-field data wrangling for the post-field equivalent and Creating Calculated Variables for the in-survey version.
Creating a derived question
From the Questions tab, click + DERIVED QUESTION.
In the dialog:
- Name — the label shown in the Questions list and in reports.
- Source questions — pick two or more existing questions. These cannot be changed after creation; if you need different sources, create a new derived question.
- Combination mode — choose one:
- All combinations (cartesian product) keeps every combination of the source options. With a 5-bucket age and a 2-option gender you get 10 combinations.
- Pick combinations to keep lets you tick only the combinations you want included. Combinations you leave unticked are dropped, so respondents who fall into them are not represented in the derived question.
Derived questions get a Derived badge in the Questions list so they're easy to spot.
Using a derived question in a report
Open the report editor and add the derived question on the Scope step like any other question. On the Layout step it can be a Row, Column, or Filter. On the Analysis step Frequency is usually what you want, and you can set its Percent Base just like a regular question.
For the wider report flow, see Reporting with MX8 Labs.