DDP is my favourite metric. It is very easy to measure, easy to understand, and gives you an idea of the quality of the testing, in terms of defects found. Many people have found it very useful. If you are one of those people, please respond to this blog and tell me about your experiences!
What is DDP?
DDP is Defect Detection Percentage. It is a measure of the effectiveness of testing (or reviewing) at finding defects. The calculation is very simple: The number of defects (bugs) found in testing* divided by the number of defects found in total so far**.
*DDP can be calculated for different iterations, different testing stages (e.g. integration and system test) or testing by a defined set of testers.
**You can choose any point in time to calculate DDP - for example, one month after an iteration is released (or when the next iteration is released).
There are lots of variations on DDP - if you have any questions, please ask!