How to use reverse logic with blank answers

Use reverse logic and branch logic when an optional question can be blank or skipped, and you need a different next step for answered versus unanswered responses. This guide walks through one practical pattern: NPS/CSAT comment follow-up—ask for contact details only when someone left written feedback.

For general logic setup and examples, see Create the logic in the survey. For choosing which question paths respondents take, see Select questions to answer with skip logic.

Goal: show a follow-up contact question only when a respondent actually left a comment.

Pattern:

one not equal rule for the answered path (non-empty comment)
one fallback in In all other cases go to for skipped or blank answers

Business Example: NPS/CSAT Comment Follow-up

Use case: you only want to ask for contact details when a respondent leaves written context.

Short form setup:

How would you rate our support? (Rating question, required)
What influenced your score? (Text question, optional)
Can we contact you to follow up on your feedback? (Email question, optional)
Thank you for your response. (Ending page)

How to Configure It in Branch Logic

Open Branch logic for the Text question What influenced your score? and click on the Add rule button.
In the If row:
- select What influenced your score?
- select operator not equal
- keep comparison value as "" (empty value)
In that rule’s Go to, select Can we contact you to follow up on your feedback? (Email question).
In In all other cases go to, select Thank you for your response. (Ending page).
Save and test both paths.

If a respondent skips the comment field, they will follow In all other cases go to.

Expected Outcome

Respondent writes a comment → goes to follow-up contact question
Respondent leaves comment blank → goes directly to thank-you end page

This keeps the survey short for most users while still capturing high-intent feedback.

Common Mistakes

Leaving In all other cases go to empty
Adding extra rules when one explicit rule + fallback is enough
Treating blank checks as a primary positive condition instead of using reverse logic

Quick Test Checklist

After saving logic, test these three runs:

Enter a non-empty comment (for example, Response time was slow)
Enter a different non-empty comment
Submit with a blank comment

Expected:

non-empty comments → follow-up contact question
blank comment → thank-you end page

FAQ

What is reverse logic for blank or skipped answers in Responsly?

You define one branch logic rule for when an optional question is answered (for example, text not equal to an empty value), and you set In all other cases go to for everyone else—including respondents who leave the field blank or skip it.

How do I send skipped optional questions to a different step?

Use In all other cases go to as the path for blank or skipped responses. Do not rely only on a single rule without a fallback; always set where respondents should go when the rule does not match.

Why use not equal with an empty comparison value?

For optional text, a not equal rule paired with an empty comparison value matches non-empty comments so you can show a follow-up. Respondents who skip or leave the field empty then follow In all other cases go to.

Where do I set branch logic in Responsly?

Open the question, then use Branch logic to add rules and In all other cases go to. For a broader overview of building flows, see the help article on creating logic in the survey.