Defect analysis course v1.0
- 1. Defect Analysis & Defect Prevention Presented By Gunesh Apte
- 2. Agenda 12-Nov-20DEFECT ANALYSIS 2 • What is Defect Analysis? • Defect Prevention • Defect Analysis Procedure • Defect Prevention Action Planning • Summary
- 4. What is Defect Analysis? 12-Nov-20DEFECT ANALYSIS 4 • Examination of information about problems • Intent to identify causes of defects so that they can be detected or prevented earlier in life cycle • Many different approaches called defect analysis or root cause analysis – employ many different techniques
- 5. Defect Analysis - Definitions 12-Nov-20DEFECT ANALYSIS 5 • Error – A mistake by a member of software team • Defect – A section of design document, source code that must be changed to correct a failure • Failure – A situation in which the software fails to execute as intended • Problem Report – Documentation that a failure has occurred during testing or use. This can be also used to document defects detected during reviews and inspections. • Software Defect is defined as “Imperfections in software development process that could cause software to fail to meet the desired expectations’’
- 6. Defect Causal Chain 12-Nov-20DEFECT ANALYSIS 6 Chemical PlantProcess Control Software Explosion Causal Analysis Software Error
- 7. Corrective Action Cycle 12-Nov-20 7 Project Software Process Process Analysis Causal AnalysisAction Planning Data Out of Control Signal & Data Proposed Action(s) Corrective Action(s)
- 8. Causal Analysis for Improvement 12-Nov-20DEFECT ANALYSIS 8 • Assigns responsibility of causal analysis of a process to the software team • Analysis is based on sample of problems rather than an exhaustive study of all the problems • Software team proposes actions to: o Prevent problems o Find problems earlier • Assigns responsibility for implementing proposals to a management action team
- 9. Improvement Cycle 12-Nov-20DEFECT ANALYSIS 9 Organization Process Software Production Software Evaluation Problem Database Software Sample of problems Baseline for future projects Problems identified Problems to fix Causal Analysis Meeting Action Team Meeting Recommended Actions Short Term Actions Long Term Actions
- 11. Defect Prevention Description 12-Nov-20DEFECT ANALYSIS 1 1 • Purpose o To identify the cause of defects and prevent them for recurring • KPA Goals o Defect Prevention Activities are planned o Common causes of defects are sought out and identified o Common causes of defects are prioritized and systematically eliminated
- 12. Need for Defect Prevention 12-Nov-20DEFECT ANALYSIS 1 2 • Defect Prevention is an important activity in any software project • In most software organizations, the project teams focus on defect detection and rework • It is advisable to implement measures that prevent the defect from being introduced in the product right from early stages of the project
- 13. Project Defect Prevention Process 12-Nov-20DEFECT ANALYSIS 1 3 Project Phase (Ongoing Work) Causal Analysis Team Action TeamProcess Assets Phase Kick0ff Meeting DP Activity Planning Defects Suggested Actions Process Improvements Improved Process Lessons Learnt Prepared Team Interim Process Improvements
- 14. 12-Nov-20DEFECT ANALYSIS 14 Defect Prevention in software lifecycle • The purpose of Defect Prevention is to identify the cause of defects and prevent them from recurring • Defect Prevention can be applied to one or more phases of the software lifecycle to improve software process quality Defect Prevention Requirement Analysis Design Coding Testing Post Go Live Analysis Action
- 15. Defect Prevention Planning 12-Nov-20DEFECT ANALYSIS 1 5 • Defines focus, composition, roles, and responsibilities of defect causal analysis team(s) • Defines charter, composition, roles, and responsibilities of action teams
- 16. Defect Causal Analysis Procedure 12-Nov-20DEFECT ANALYSIS 16
- 17. Orthogonal Defect Analysis 12-Nov-20DEFECT ANALYSIS 1 7 • Orthogonal-defect classification scheme was developed at IBM in the 1990s by Ram Chillarege • Collect data on all the defects including their characteristics • Classify all defects into various defect types • To facilitate defect analysis, for each defect, its categorization in a fixed set of categories should also be recorded
- 18. Orthogonal Defect Analysis 12-Nov-20DEFECT ANALYSIS 1 8 Orthogonal Defect Classification What are the attributes of the defects? Defect Causal Analysis When are defects being injected? Defect Trigger Analysis How are defects being detected? ODC provides a structure for the defect data
- 19. 19 High/Low Level DesignInterface Configuration MgmtBuild/Package/Merge ImplementationTiming/Serialization ImplementationAssignment LLD/ImplementationChecking Low Level DesignLogic Architecture/HLDFunction Defect Types - Example
- 20. Pareto Analysis using chart 12-Nov-20DEFECT ANALYSIS 2 0 • Pareto analysis is a common statistical technique used for analyzing the root causes of defects • Number of defects found belonging to different types is computed from the defect data and is plotted as a bar chart in the decreasing order • Line chart is also plotted on the same graph showing the cumulative number of defects as we move from types of defects given on the left of the x-axis to the right of the x-axis • Pareto Chart makes it clear which types of defects contribute to 80-85% of the total defects
- 21. Pareto Chart - Example 12-Nov-20DEFECT ANALYSIS 2 1
- 22. Root Causes and Preventive Actions 12-Nov-20DEFECT ANALYSIS 2 2
- 23. Cause Effect Diagram 12-Nov-20DEFECT ANALYSIS 2 3 • Sample graphical technique • Helps to sort and relate many factors • Developed as a team (facilitated) • Focus for discussion - not a definitive result • Also called an Ishikawa or Fishbone Diagram
- 24. Diagramming Steps 12-Nov-20DEFECT ANALYSIS 2 4 • State problem (effect) – Use statement of systematic error – Draw main branch • Insert headings for generic causes o Process / Methods o People o Tools / Environment o Input • Highlight principal / operative cause(s) - circle
- 25. Cause Effect Example 12-Nov-20DEFECT ANALYSIS 2 5 More Logical errors in software code Input Process People Tools Lack of knowledge Lack of Coding Standards Poor Design Templates Inadequate IDE tools
- 26. Defect Prevention Action Team Activity 12-Nov-20DEFECT ANALYSIS 26
- 27. Action Team Organization 12-Nov-20DEFECT ANALYSIS 2 7 • Meets regularly to consider proposed actions • Must include management – needs resources • May include technical personnel • Select and prioritize proposals • Resolve conflicts and combine related proposals • Plan and Schedule implementation • Allocate resources and assign responsibility • Monitor progress and effectiveness • Communicate actions and status to the teams
- 28. DP Action Team Meeting Outputs 12-Nov-20DEFECT ANALYSIS 2 8 Organization Process Software Production Software Evaluation Problem Database Software Sample of problems Baseline for future projects Problems identified Problems to fix Causal Analysis Meeting Action Team Meeting Recommended Actions Short Term Actions Long Term Actions • Design Process improvement • Coding Standards refinement • UI layout improvement
- 30. Summary 12-Nov-20DEFECT ANALYSIS 3 0 • Most organizations with well-defined processes will benefit from application of Defect Causal Analysis • Maximum benefit can be obtained from o Following a systematic approach o Involving the developers o Pursuing a strategy derived from an objective understanding of improvement opportunities • DCA can be applied to any process that receives feedback on its defects or failures
- 31. 12-Nov-20DEFECT ANALYSIS 31 Summary Defect Identification Defect Classification Defect Analysis Root Cause Analysis Preventive Actions Process Improvement
- 32. References 12-Nov-20DEFECT ANALYSIS 3 2 • Ajit Shenvi, 2009, “Defect Prevention with Orthogonal defect classification”, In proc- ISEC-09, February 23-26 2009 • Defect Prevention by SEI CMM Model Version 1.1, http://repository.cmu.edu/cgi/viewcontent.cgi?article=1179&context=sei • Mukesh Soni, 1997, “Defect Prevention : Reducing cost and improving quality’’ published in IEEE Computer (Volume 30, Issue 8), August 1997 • Sakthi Kumaresh, R Baskaran, “Defect Analysis and Prevention for Software Process Quality Improvement” published in International Journal of Computer Applications (0975 – 8887) Volume 8 – No.7, October 2010