Engagement
Form abandonment
Also called form drop-off.
Form abandonment is started forms that never reach a successful submit. It is the leak between interest and a lead.
How it is measured
A start is the first focus or keystroke. A success is a confirmed submit or a thank-you view. Abandonment is starts minus successes, divided by starts.
In Tarsier, send one custom event on first focus and one on success, then compare the two counts over the same dates.
Worked example
A landscaping firm's quote form gets 480 starts and 130 submits in a month, so 73 percent abandon. Field data shows 190 of the leavers stop at the photo-upload step.
The firm makes the upload optional. Abandonment drops to 58 percent over the next month.
How it differs
Form abandonment counts leavers. Abandonment rate is the generic ratio for any process. Cart abandonment is the shop version. A form is smaller, so the diagnosis can go field by field.
Common errors
Counting visitors who never started. Treating validation failures as abandonment. Ignoring double submits. Failing to track success at all. Forgetting that mobile keyboards cover fields.
In practice
Fix the highest drop-off field first, then re-measure after a month before touching a second one.