Ali Demirbaş - Lab
TRGet in touch

Forms & Signup

Modal Form vs In-Page Form A/B Test Example

A modal can make the form more prominent but cover information behind it.

  • Forms & signup
  • Form completion rate

Option A vs Option B

Two alternatives; neither is the incumbent.

Changed
Options
Page
Forms & signup
Difference
changed

Hypothesis

An inline form keeps the page context visible, though visitors may overlook it. Compare successful submissions among all eligible assigned visitors, including those who never open the modal.

How to run this test

Primary metric

Form completion rate

Assign eligible visitors before they see either presentation and compare successful submissions.

Other metrics

  • Form start rateMeasure intentional first interaction with the form the same way in both arms, not modal opens.
  • Data loss after modal dismissalThis diagnostic exists only in the modal arm; do not compare it directly across arms.
  • Page exit rateCompare page exits among visitors assigned to each form presentation.

What to check before and during the test

  • PresentationShow the same form inline in the page or in a modal.
  • Keep constantKeep fields, validation and support information the same; define when the modal opens before launch.
  • Data persistenceCheck whether entered information is preserved when the modal is closed and reopened.
  • Browser behaviorVerify the browser back button behaves as expected in both presentations.
  • Accessibility and deviceCheck keyboard dismissal, focus containment and usability on small screens.

Setup mistakes to avoid

  1. 1Do not use a modal that cannot be closed or has a hidden close control.
  2. 2Do not change backdrop darkness in the same test; that is a separate variable.
  3. 3Do not call a modal a winner if it closes on outside click and silently loses entered data.
  4. 4Do not compare a cramped half-screen mobile modal with a desktop result.
  5. 5If opening the modal depends on user behavior, keep the trigger rule fixed throughout the test.