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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.