I have few doubts in the Defect leakage ratio calculation formula.
I found one of the formula to calculate as below: CD=No. of Defects raise by customer after release
DR=No. of Defects raised by Tester before release
ID- No. of invalid Defects from Defects raised by tester before release(Eg. Duplicate, CannotFix, error in test environment etc.)
Formula to calculate Defect Leakage Defect Leakage=(CD/DR-ID)*100
Here my doubt is related to the period to consider and catagery of bugs found.
Eg:- Release1 happened on April 27th 2018 and Release2 happened on Sep 24th 2018.
Now to calculate Defect leakage ratio for Release2: What duration has to consider?
For DR and ID, it is April 28th 2018 to Sep 24th 2018 and defected found internally in this duration. For CD whether needs to consider from Sep 25th 2018 to till current Date? Is won't be the Release2 Production leakage till next release whatever productions bugs raised. If yes, then when exactly the metric will be calculated?
Another doubt is, if one production bug raised after Sep 25th 2018(After Release2) and developer found the issue exists from the old releases say Release1 then whether needs to consider this bug in the Release2 defect leakage ratio?
Please clarify me?