Probably I am missing some key aspect here, because I simply have no idea how this metric is supposed to tell me anything described by the authors:Defect Open and Close rate = (Defects found during testing in a  release / (Defects found during testing in a release + Defects found  after release) *100What is it?While there are numerous defect statuses which indicate the current  state of an identified flaw, they can typically be categorized as  either open or closed.Why is it important?The sheer number of defects that are encountered during a projects  run can make them difficult to keep tabs on. If team members are not  diligent about measuring the current status of their programs flaws,  certain defects could slip through the cracks and show up in the  finalized release. Furthermore, comparing the frequency of open  defects with close rates will also provide insight into the ability of  testers and developers to work together to identify and address  software issues.http://www.getzephyr.com/resources/whitepapers/qa-metrics-value-testing-metrics-within-software-development
Defect metrics - open and close rate explanation
testing;quality;metrics