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8/6/2019 SQE(Lecture 6)
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Software Quality Metrics
Software quality metrics can be divided further into
1) End-product quality metrics
2) In-process quality metrics.
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End Product Quality Metrics:
End-product quality is usually measured by the number
of "bugs" (Functional defects) in the software or by
how long the software can run before a critical failure
(a "crash.").
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In-Process quality metrics used to measure duringdevelopment process.
Ex: In-Process Quality during Development (derived
by linking bugs to application objects)
1) Defect Density: Number of defects / Size
of application
2) Source of Defects: Number of Defects
originating in each phase3) Requirements Quality: Number of Defects
originating in Requirements phase
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Software Documents
A written document to develop a software product
produced in response to a request for tenders by an
external client.
The documents associated with a software project
being developed have a number of associated
requirements:
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They should act as a communication medium
between members of the development team.
They should provide information for management to
help them plan, budget and schedule the software
development process.
Some of the documents should tell users how to use
and administer the system.
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Documentation produced falls into two classes.
1) Process documentation.
2) Product documentation
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Process documentation:
These documents record the process of
development and maintenance.
Example of Process documentation are
1) Planning
2) scheduling.
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Product documentation:
This documentation describes the product that is
being developed. System documentation describes the product from
the point of view of the engineers developing and
maintaining the system.
User documentation provides a product description
that is oriented towards system users
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Product metrics
Product metrics describe the characteristic of thefollowing.
1) Product size.
2) Complexity.
3) Design features.
4) Performance.
5) Quality Level.
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Mean time to failure metrics.
Defect density metrics.
Customer problems metrics.
Customer satisfaction metrics
Function Points
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Mean-Time-To-Failure Metrics
Measures the time between failures.
Mean-time-between-failure (MTBF).MTBF= MTTF+MTTR
Where, MTTF= Mean-time-to-failure (Is an
inverse of failure rate)MTTR=Mean-time-to-repair
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Defect Density Metrics
Compares the defect rate of the software products
It is number of defects over opportunities for error
during a specified time.
Defect rate = (Number of defects/OFE)
Where,OFE= Opportunities for error ( or size of the software,
express in KLOC or number offunction points).
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Difference between MTTF and
Defect density Metrics.