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Defect removal effectiveness


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Anna University, Final CSE, Software Quality Management

Anna University, Final CSE, Software Quality Management

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  • 1. Defect Removal EffectivenessDefect Removal Effectiveness Software Quality Management  Software Quality Management Unit 3 G. Roy Antony Arnold G R A A ld Asst. Professor / CSE GRAA
  • 2. • Defect removal i one of the top expenses i f l is f h in any software project and it greatly affects schedules.• Effective defect removal can lead to reductions in the development cycle time and g good product quality. p q y• It is important for all development organizations to measure the effectiveness of their defect removal processes. GRAA
  • 3. • Fagan (1976) defined error detection efficiency as: Errors found by an Inspection X 100% Total errors in the product before inspection• Joness definition (1986), stated here, is very similar to Fagans: – Removal Efficiency =  Defects found by removal  operation y p X 100% Defects present at removal operation Defects found X 100% Defects found + Defects not found (found later)• IBM Houston received the first NASA Excellence Award for Quality  and Productivity in 1987 GRAA
  • 4. • One of the four metrics IBM used to manage quality is One of the four metrics IBM used to manage quality is  the early detection percentage, which is actually  inspection defect removal effectiveness Early Detection Percentage = Number of major inspection errors Number of major inspection errors X 100% Total number of errors• where total number of errors is the sum of major  inspection errors and valid discrepancy reports  (discrepancy report is the mechanism for tracking test  (di t i th h i f t ki t t defects). GRAA
  • 5. GRAA
  • 6. • The effectiveness measure by Dunn (1987) differs little from The effectiveness measure by Dunn (1987) differs little from  Fagans and from Joness second definition. • Dunn‘s definition is: Effectiveness of activity (development phase ) = Number of defects found by activity Number of defects found by activity X 100% Number of defects found by subsequent activities• This metric can be tuned by selecting only defects present at  the time of the activity and susceptible to detection by the  y p y activity. GRAA
  • 7. • Daskalantonakis (1992) describes the metrics used at Motorola for  software development. software development Total Defect Containment Effectiveness (TDCE) = Number of pre‐release defects Number of pre‐release defects Number of pre‐release defects + Number of post‐release defects Phase Containment Effectiveness (PCEi) = Number of Phase i errors Number of Phase i errors + Number of phase i defects• Where phase i errors are problems found during that development Where phase i errors are problems found during that development  phase in which they were introduced, and • Phase i defects are problems found later than the development  phase in which they were introduced. phase in which they were introduced. GRAA
  • 8. Defects removed (at the step) ( ) X 100%Defects existing on step entry + Defects injected during development of the step GRAA
  • 9. GRAA
  • 10. • B d on a special study commissioned b th D Based i l t d i i d by the Department t t of Defence, Jones estimates the defect removal effectiveness for organizations at different levels of the development process capability maturity model ( (CMM):) – Level 1: 85% – Level 2: 89% – Level 3: 91% – Level 4: 93% – Level 5: 95% l• These values can be used as comparison baselines for organizations to evaluate their relative capability with regard to this important parameter. GRAA
  • 11. • Based on historical and recent data from three software engineering organizations at General Dynamics Decision Systems, Diaz and King (2002) report that the phase containment effectiveness by CMM level as follows: – Level 2: 25.5% – Level 3: 41.5% – Level 4: 62.3% – Level 5: 87.3% GRAA
  • 12. Phase Inserted Phase Inserted Cumulative % of Defects  Cumulative % of Defects removed through Acceptance  TestRequirements 94%Top Level Design Top‐Level Design 95%Detailed Design 96%Code and  UnitCode and Unit Test 94%Integration Test  75%System TestSystem Test 70%Acceptance Test 70% GRAA