Regression checkers is a tool currently in the WME beta, which further assists in protecting the quality of the map. This tool does not work in conjunction with the throttling system, but is an additional layer of protection to overall map quality.
Regression checker warns editors of edits which might harm the map and/or cause map issues.
Every save is analysed against a list of possible issues, recent drives in an area, and current road structure. Waze estimates how correct or risky an edit is and gives it a risk score. For example - a very large change in a busy highway which cannot work with current driving patterns is expected to have a very high risk score, while a small change in a side street which seems to comply with current driving patterns will have a low risk score.
After each save, the user will see one of three save results:
* '''Save successful'''- everything is cool.
* '''Error''' - Serious potential issue. A list of the issues appears and their locations. The user needs to review the issues and fix them. Only then will they be able to save again.
Effect of ranks=====
There are different warning and error thresholds for each rank.
Higher ranking users are more likely to get 'successful' where a lower ranking user might get a warning. Furthermore, a higher ranking user may get a warning for a questionable edit, where a lower ranking user might get an error.