What is Issue Churn?
In the context of Agile software development, issue churn is a metric that can be used to measure the efficiency of a team.
Issue churn is a term used to describe the amount (issues or points) that have rolled over from one sprint to the next.
It is a measure of the amount of work that has not been completed in a given sprint. The higher the churn count, the less efficient the team is.
It's also important to represent Issue Churn as a Rate... that is, the amount of stories that are rolled over from one sprint to the next compared to the total number of stories that were planned for the sprint. This is a more accurate representation of the team's efficiency.
Some Issue Churn is Ok
It's important to note that some issue churn is ok. In fact, it's expected. The goal is to minimize churn as much as possible, but it's not always possible to eliminate it completely.