quality planning and defects

8/7/2019 Quality Planning and Defects

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Quality PlanningAnd

Defect

EstimationPre

sented

byBas

ker

George


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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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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%

quality planning and defects

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