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8/7/2019 Quality Planning and Defects
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Quality PlanningAnd
Defect
EstimationPre
sented
byBas
ker
George
8/7/2019 Quality Planning and Defects
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Quality Planning
Not only Cost & Schedule but QUALITYis also a major factor in determining the
success of the project.There are many characteristic whichdefine Quality.
But the de facto industry standard
definition of Quality is: The number ofdefects per unit size in the deliveredsoftware
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Definition of Defect
What is defect?
Defect in software is somethingthat causes the software tobehave in a manner that isinconsistent with the requirementof the need of the customer.
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Cont.
For High Quality software, the finalproduct should have as few defects
as possible.Since Software Development is aHUMAN activity, it is not possible toprevent injection of all defects.
But it can be reduced by Qualitycontrol activity, which is Review &Testing.
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Cont
In this chapter we shall study how qualitycontrol activities are Planned & Managed
The Software Product Engineering KPA of CMMLevel 3 includes some key practices that isused to test software for Quality.
Software Quality Management KPA at Level 4
focus on Quantitatively Planning & Controllingthe quality in a project.
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Quality ManagementThe task of quality management is
To plan suitable quality control activities
Properly execute & control these activities
such that most defects are detected duringIn-Process & removed before delivery.
In process activities include:
Requirement Review, Design Review, Code
review Unit Testing, Integration Testing, SystemTesting & Acceptance Testing
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Procedural Approach toQuality Management.
Defects are detected by performing Reviewor Testing
Review are structured, human orientedprocess
Testing is the process of executing softwareto identify defects
In procedural approach for Qualitymanagement, procedures & guidelines forreview & testing are established.
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Cont
For example, the system testingprocedure involves making a test plan
that lists all test cases that should beexecuted during testing, getting theplan reviewed & then executing theplan.
The above approach is called proceduralapproach to defect identification.
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Defect Injection & Removal
during Development process
RequirementAnalysis
R R RDesign Coding
UT IT/IST AT
R- Defect Removal
Defect Injection
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Quantitative Approach toQuality Management
Quantitative Quality Management isthe process of controlling the Qualityof the software based onquantitative data.
It makes use of software reliabilitymodel.
These model indicate weather thereliability is acceptable or moretesting is needed.
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Cont
A good quality management approachshould provide warning signs early in theproject & not just towards the end.
Early warning allow for timely intervention
Therefore during project execution someparameter are measured & compared withthe estimated values to determine whetherthe project is going along desired path.
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Cont
Another quality concept is defectremoval efficiency.
DRE=
Defects found by the QCactivity
Total defects in the product before the QC
activity
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Quantitative Quality Managementthrough defect prediction
This approach makes use ofobserved defects pattern in
previous projects to forecast defectlevels.
RR
HL
D
DD
UT
ITST
AT
Operation
D
efects
Time
Defects duringdiff. Review
phase
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Quantitative QualityManagement Planning
This process involves setting theQuality goals for the project.
The quality goal is the expected noof defects during acceptance test.
The primary source for setting the
quality goals are PDB & PCB
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Cont
Estimate forAT defects(P)=
AT defects(SP) X effortsestimate(P)
Actualefforts(SP)
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Estimating Defects for otherstage:
From the estimate of the total no ofdefects that will be introduced during
the course of the project, the defectlevel for different testing stage areforecast by using percentage
distribution of defects as given in PCB
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Cont
Defect distribution at Infosys PCBProcess Stage %tage of total
defectsSRS +HLD +Detaildesign Reviews
15% - 20%
Code review+Unittesting
50%-70%
Integration testing +System testing
20%-28%
Acceptance Testing 5%-10%