Why does a ranking jump up and down from day to day?

Google often serves different result pages minutes apart. Serpified re-fetches any drop of three or more places before recording it, keeps the better page, and marks the day unstable when the two disagree, so the graph shows real movement.

Part of Rank tracking in the Serpified knowledge base. Answers are kept current with the product; if one is out of date, tell us and we fix it.