SERP flux detection

What it is

Rankings move every day. Almost all of that movement is noise, and a tool that alerts on every change trains you to ignore it. The real question is narrower: has something structural changed?

SERP flux detection answers that question about the rankings you track, and — just as importantly — explains its reasoning. When it tells you a structural shift is underway, you can see the numbers that led to the conclusion.

How it works

• Robust z-scores against a rolling baseline. A median absolute deviation approach rather than a standard deviation, because a single dramatic mover should not hide the rest of the field.
• CUSUM change-point detection, which spots a slow drift that never produces a single alarming day but is unmistakable over a fortnight.
• CTR-weighted volatility, so movement on a high-traffic keyword counts for more than movement on one nobody searches.
• Severity classification, so a minor shuffle and a site-wide collapse do not arrive looking the same.

What it does for your site

It turns "our traffic dropped, when did that start?" into a timestamp. It distinguishes a site-wide event from a single-page problem, which changes who you assign it to. And it catches the slow drift that daily noise hides — the pattern where nothing looks wrong on any given day but the trend has been down for three weeks.

Where the results go

Volatility drives alerts and feeds forecasting, where a detected shift becomes a reason to re-run the numbers. Rank movement is also what the SERP simulator diffs a draft against.