Beyond the technical measures.
WHAT AFFECTS WHETHER SOMEONE STAYS
How quickly they see the content Whether the page jumps around while loading Whether interruptions cover what they came for Whether it works on their device Whether they can find what they wanted
WHAT DRIVES PEOPLE AWAY
Pop-ups appearing immediately Cookie banners covering the content Autoplaying video or audio Advertisements pushing content down as they load Text too small to read Navigation that does not work on a phone
WHY IT MATTERS FOR SEARCH
Engines measure some of this directly through Core Web Vitals, and infer more from behaviour.
More practically, a visitor who leaves immediately did not become a customer regardless of ranking.
THE INTERRUPTIONS QUESTION
An email signup pop-up may gain subscribers and lose visitors. Measure both rather than assuming.
Delaying it, or triggering it on exit, is usually a better trade.
THE TEST
Load your own site on a phone, on mobile data, as a first-time visitor. What you notice is what visitors notice.
