DefinitionThe defect detection percentage (DDP) gives a measure of the testing effectiveness. It is calculated as a ratio of defects found found prior to release and after release by customers. To be able to calculate that metric, it is important that in your defect tracking system you track: - affected version, version of software in which this defect was found.
- release date, date when version was released
You can also calculate DDP from sub-metrics: - Number of escaped defects
- Number of defects (at the moment of software version release)
DDP = Number of defects at the moment of software version release / Number of defects at the moment of software release + escaped defects found. DimensionsIt should be possible to monitor Defect Detection Percentage in following dimensions: - Affected version
- Project/Product. To aggregated DDP over all released versions of the project or product.
- Date
PresentationAs DDP ratio is changing over time as more defects are found by customers working with the version best visualization is using a line chart that starts with 100% at moment of software version release and a line representing a trend of how fast DDP is declining.
For iterative processes, it makes sense to see a bar chart representing DDP value for each iteration/sprint after let's say 1 month of corresponding version release.
ExampleFor example, suppose that 90 defects were found during QA/testing stage and 20 defects were found by customers after the release. The DDP would be calculated as 90 divided by (90 + 20) = 81.8%
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