Ali Demirbaş - Lab
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Forms & Signup

Autofocus on the First Form Field A/B Test Example

Focusing the first field may remove one step before typing begins.

  • Forms & signup
  • Form start rate

Control vs Variant

What the interface does on its own is the variable.

Changed
Behavior
Page
Forms & signup
Difference
changed

Hypothesis

But the page could scroll before visitors finish reading, or the mobile keyboard could open unexpectedly. Measure intentional user input, not the focus event created by the variant.

How to run this test

Primary metric

Form start rate

Count intentional user input; exclude programmatic focus and autofill events.

Other metrics

  • Form completion rateCompare successful submissions among assigned visitors who see the form.
  • Page exit rateCompare exits after automatic focus among the same eligible visitors.
  • Form focus loss rateCheck whether focus unexpectedly leaves the form or page, using the same event tracking in both arms.

What to check before and during the test

  • FocusIn the variant, focus the first field once the page is ready, only if the form is visible.
  • Keep constantKeep form position, field size, copy and validation unchanged.
  • ScrollingRecord whether focus skips explanatory copy or causes unexpected scrolling.
  • KeyboardCheck the mobile keyboard and the usable portion of the form.
  • AccessibilityVerify that keyboard order and screen-reader focus follow the expected sequence.

Setup mistakes to avoid

  1. 1Do not force-scroll visitors to a form in the middle or at the bottom of the page.
  2. 2Do not enable mobile autofocus based on desktop results alone.
  3. 3Do not change focus and field size together.
  4. 4When focusing a form in a modal, keep its close button in the focus order.
  5. 5Do not trigger autofocus before the page is ready and cause focus to jump.