AI answers are not deterministic. Ask the same engine the same question twice and you can get different phrasing, a different set of businesses, and a different order. A score that moves a few points between scans without any change on your side is normal and is the honest reflection of a system that genuinely varies.
What we do about it
Every answer is stamped with the engine, the model version and the date it was fetched, so you can always see what produced a number.
You can ask each question more than once per scan. It costs proportionally more and gives a steadier picture, which is why it is off by default.
We never recalculate an old scan. Scores are written once. If we change how scoring works, or add a new check to Site setup, old scans keep their original numbers and the comparison view tells you the two runs are not comparable rather than quietly subtracting them. Every answer and every check result is still there to compare side by side, and a check we added shows as new.
When we add checks
Now and then we add something new to Site setup, because AI tools start reading something they did not read before. When we do, this is what happens.
Scans you have already run keep the score they were given. Nothing is recalculated.
Your next scan is scored over the longer list, so Site setup can go up or down with nothing changed on your site. That is the one time a deterministic score moves on its own.
History says the technical checks changed between the two scans and does not subtract the scores. The added checks appear there as new, and on your results as new findings with a fix beside them.
The check registry version printed under your Overview and on the methodology page tells you which list a score was measured against.
The most recent addition checks four things: whether a shared link to your site shows a proper preview, whether each page has a clear title and summary and is not hidden from search engines, whether each page has one main heading, described photos and a declared language, and whether your structured data gives your full business details.
When a change is real
Movement in the technical readiness score is real when both scans were measured against the same checks. Those checks are deterministic, so if that number moved, something on your site changed. If we added checks in between, History says so. Movement in visibility is worth trusting when it is large, consistent across engines, or lines up with a fix you made. The methodology page shows the exact arithmetic.