DEFECT DETECTION EFFICIENCY (DDE) is the percentage of defects detected during a phase/stage divided by the total number of defects. Or, it can also be defined as the percentage of defects detected prior to a phase / stage.
ISTQB Definition
- defect detection percentage: The number of defects found by a test level, divided by the number found by that test level and any other means afterwards.
Elaboration
- defects:
- Are confirmed and agreed upon (not just reported).
- Dropped defects are not counted.
- phase:
- Can be any phase in the software testing life cycle. Or, specifically, any software testing level.
Formula 1
-
DDE = (Number of Defects Detected in a Phase / Total Number of Defects) x 100 %
Formula 2
-
DDE = (Number of Defects Detected Prior to a Phase / Total Number of Defects) x 100 %
Example
| Phase | Defects Detected | DDR (Formula 1) | DDR (Formula 2) | ||||
|---|---|---|---|---|---|---|---|
| Unit Testing | 20 | 15.2% | 15.2% | ||||
| Integration Testing | 12 | 9.1% | 24.2% | ||||
| System Testing | 82 | 62.1% | 86.4% | ||||
| Acceptance Testing | 15 | 11.4% | 97.7% | ||||
| Production | 3 | 2.3% | 100.0% | ||||
| TOTAL | 132 | 100.0% |
Sample Interpretation:
- DDR (Formula 1) of Unit Testing is just 15.2% and could be bettered. Earlier the detection, less costlier the solution.
- Assuming that the internal team does Unit, Integration and System testing, the DDR (Formula 2) is only 86.4% at the level of System Testing which means that the team is weak and is letting the defects slip to the customer / users (Acceptance Testing & Production).
Uses
- For measuring the quality of the processes (process efficiency) within software development life cycle; by evaluating the degree to which defects introduced during that phase/stage are eliminated before they are transmitted into subsequent phases/stages.
- For identifying the phases in the software development life cycle that are the weakest in terms of quality control and for focusing on them.
- For assessing the performance of the team / software testers. [Take extra caution while using this though; there are many factors involved in their performance and solely using this metric to judge them would be unfair.]
Learn about a somewhat related and useful metric: DEFECT AGE.
Last Updated on March 12, 2023 by STF