Defect rate is the count of issues marked as bugs that were created before linked stories and/or issues were marked complete. This metric helps you understand the frequency of bugs identified before completing a story or issue.
HOW IT’S MEASURED
Defect rate is calculated per Epic by counting the number of issues with type:bug that were created before linked stories and/or issues were marked complete. Defect rate can also be represented as a percentage by dividing the number of bugs by the total number of stories or issues in an Epic.