Getting started with DDP
You probably already have the information you need to calculate your own DDP - the number of defects found in testing, and the number that were found later (e.g. a later stage of testing or reported to Support).
For example, if system testing (ST) found 50 bugs, and user acceptance testing (UAT) found 25, the DDP of ST was 67% (50 / 75).
Take a project that finished 3 to 6 months ago and calculate what the DDP was for that. Now you have a starting point to see how your testing is changing over time.
Not all bugs are created equal! When you start measuring DDP, you might want to use only the highest one or two severity ratings. Or you could have one DDP for high severity, and one for all bugs.
If you have any questions about DDP please ask!