An investigation takes a change in a metric and does four things.
- It decomposes the change into impressions, position, click-through and query or page mix.
- It lines the change up with recorded events such as deploys, annotations and known external updates, allowing one day of slack because Search Console dates are Pacific time and events are UTC.
- It tests each candidate cause against the evidence and updates its posterior.
- It reports the causes with their tiers and the alternative explanation for each.
Provisional days are excluded from the comparison. A change inside normal noise is reported as within noise and is not given a cause.
No cause is labelled confirmed below the top tier of the confidence scale.