Quality Planning And Defect Estimation Presented by Basker George

Quality Planning Not only Cost & Schedule but QUALITY is also a major factor in determining the success of the project. There are many characteristic which define Quality. But the de facto industry standard definition of Quality is: “ The number of defects per unit size in the delivered software ”

Definition of Defect What is defect? Defect in software is something that causes the software to behave in a manner that is inconsistent with the requirement of the need of the customer.

Cont …. For High Quality software, the final product should have as few defects as possible. Since Software Development is a HUMAN activity, it is not possible to prevent injection of all defects. But it can be reduced by Quality control activity, which is Review & Testing.

Cont … In this chapter we shall study how quality control activities are Planned & Managed The Software Product Engineering KPA of CMM Level 3 includes some key practices that is used to test software for Quality. Software Quality Management KPA at Level 4 focus on Quantitatively Planning & Controlling the quality in a project.

Quality Management The task of quality management is To plan suitable quality control activities Properly execute & control these activities such that most defects are detected during “ In-Process ” & removed before delivery. In process activities include: Requirement Review, Design Review, Code review Unit Testing, Integration Testing, System Testing & Acceptance Testing

Procedural Approach to Quality Management. Defects are detected by performing Review or Testing Review are structured, human oriented process Testing is the process of executing software to identify defects In procedural approach for Quality management, procedures & guidelines for review & testing are established.

Cont … For example, the system testing procedure involves making a test plan that lists all test cases that should be executed during testing, getting the plan reviewed & then executing the plan. The above approach is called procedural approach to defect identification.

Defect Injection & Removal during Development process Requirement Analysis R R R Design CodingUTIT/IST AT R- Defect Removal Defect Injection

Quantitative Approach to Quality Management Quantitative Quality Management is the process of controlling the Quality of the software based on quantitative data. It makes use of software reliability model. These model indicate weather the reliability is acceptable or more testing is needed.

Cont … A good quality management approach should provide warning signs early in the project & not just towards the end. Early warning allow for timely intervention Therefore during project execution some parameter are measured & compared with the estimated values to determine whether the project is going along “ desired ” path.

Cont … Another quality concept is defect removal efficiency. DRE= Defects found by the QC activity Total defects in the product before the QC activity

Quantitative Quality Management through defect prediction This approach makes use of observed defects pattern in previous projects to forecast defect levels. RR HLD DD UT IT ST AT Operation Defects Time Defects during diff. Review phase

Quantitative Quality Management Planning This process involves setting the Quality goals for the project. The quality goal is the expected no of defects during acceptance test. The primary source for setting the quality goals are PDB & PCB

Cont … Estimate for AT defects(P) = AT defects(SP) X efforts estimate(P) Actual efforts(SP)

Estimating Defects for other stage: From the estimate of the total no of defects that will be introduced during the course of the project, the defect level for different testing stage are forecast by using percentage distribution of defects as given in PCB

Cont … Defect distribution at Infosys PCB Process Stage%tage of total defects SRS +HLD +Detail design Reviews 15% - 20% Code review+Unit testing50%-70% Integration testing + System testing 20%-28% Acceptance Testing5%-10%