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Conditional logic is a set of rules attached to a block. Each rule reads when this is true, then do that — skip ahead, require an answer, or update a variable.

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Where logic lives

Logic belongs to the block, not to a single question. Scroll to the foot of any block in the survey editor and you will find Conditional Logic below the question list. The Conditional Logic section at the foot of a block

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Terminology

  • Condition: a rule that decides whether an action runs.
  • Action: what happens when the condition is met.

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Building a rule

Click Add logic + and fill in the sentence. A rule that routes savings-account respondents to a second block
1

Choose what to test

The When row starts with a source. It can be the answer to a question, the value of a variable, or the value of a hidden field.
2

Choose an operator

The operators on offer depend on the source. A single-select question can be compared with Equals, Does not equal, Equals one of and Is submitted; a free text question adds Contains, Starts with, Ends with and their negations.The operator list for a single-select question
3

Choose a value

Compare against a fixed value, or against another question’s answer, a variable, or a hidden field.
4

Choose an action

The Then row is what happens when the condition holds.The three actions: Calculate, Require Answer and Jump to block

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Actions

  • Calculate: change a variable’s value. The result is available to every later question, and to the rules below this one.
  • Require Answer: make an optional question required. Only questions that are optional to begin with can be required this way.
  • Jump to block: send the respondent to a specific block instead of the next one.
A rule can carry several actions. They run in the order they are listed.

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Everyone else

Under the rules sits All other answers will continue to. This is the fallback for respondents who match none of the conditions, and it is set to the next block unless you change it.

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Several conditions in one rule

The ⋮ button beside a condition adds another condition below it, duplicates it, removes it, or wraps it in a group. Conditions are joined with and or or, and a group is how you mix the two without ambiguity — the same reason brackets exist in arithmetic.

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Several rules in one block

Add logic + adds another rule. Rules are evaluated top to bottom, and the first one whose condition holds decides where the respondent goes. Drag them to change the order.