The blue line represents cycle time for user story, while the red line shows cycle time for bugs. The chart above shows how cycle time has changed from month to month.
First, we see that cycle time has been very unstable. It changes from 7 to 21 days for user stories. This is a clear sign of significant unevenness (or mura — a type of waste in lean) and something should be done about it. Second, there's a correlation between cycle time for user stories and bugs. We see simultaneous spikes where cycle time for user stories is larger.