Defect Detection Efficiency Metrics

DEFINITION
Defect Detection Efficiency (DDE) is the number of defects detected during a phase/stage that are injected during that same phase divided by the total number of defects injected during that phase.
ELABORATION

• defects:
  • Are confirmed and agreed upon (not just reported).
  • Dropped defects are not counted.
• phase:
  • Can be any phase in the software development life cycle where defects can be injected AND detected. For example, Requirement, Design, and Coding.
• injected:
  • The phase a defect is ‘injected’ in is identified by analyzing the defects [For instance, a defect can be detected in System Testing phase but the cause of the defect can be due to wrong design. Hence, the injected phase for that defect is Design phase.]

FORMULA

• DDE = (Number of Defects Injected AND Detected in a Phase / Total Number of Defects Injected in that Phase) x 100 %

UNIT

• Percentage (%)

TARGET VALUE

• The ultimate target value for Defect Detection Efficiency is 100% which means that all defects injected during a phase are detected during that same phase and none are transmitted to subsequent phases. [Note: the cost of fixing a defect at a later phase is higher.]

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.

EXAMPLE

Phase	Injected Defects	Injected Phase Specific Activity	Detected Defects	Detected Phase Specific Activity	Detected Defects that were Injected in the same Phase	Defect Detection Efficiency
Require- ments	10	Require- ment Develop- ment	4	Require- ment Review	4	40.00%[= 4 / 10]
Design	24	Design	16	Design Review	15	62.50%[= 15 / 24]
Coding	155	Coding	23	Code Review	22	14.19%[= 22 / 155]
Unit Testing	0	—	25	Unit Testing	—	—
Integra- tion Testing	0	—	30	System Testing	—	—
System Testing	0	—	83	Integration Testing	—	—
Accept- ance Testing	0	—	5	Acceptance Testing	—	—
Opera- tion	0	—	3	Operation	—	—

• The DDE of Requirements Phase is 40.00% which can definitely be bettered. Requirement Review can be strengthened.
• The DDR of Design Phase is 62.50 % which is relatively good but can be bettered.
• The DDE of Coding Phase is only 14.19% which can be bettered. The DDE for this phase is usually low because most defects get injected during this phase but one should definitely aim higher by strengthening Code Review. [Note: sometimes, Coding and Unit Testing phases are combined.]
• The other Phases like Integration Testing etc do not have DDE because defects do not get Injected during these phases.