Software Metrics

Swati J. PatelM. E. (CSE)

Agenda• Definition• Need• Classification• Product Metrics

– Size Metrics– Complexity Metrics– Halstead’s Product

Metrics– Quality Metrics

• A Metrics Programme– GQM Approach

DefinitionA software metric is a standard of measure of a degree to which a software system or process possesses some property.A Metric is a quantitative measure of the degree to which a system, system component, or process possesses a given attribute. Software Metrics are used to measure the quality of the project. Simply, Metric is a unit used for describing an attribute. Metric is a scale for measurement.

Need• Software testing is the process of identifying the flaws or

defects in the system and make sure it is compliant with the client requirements before releasing it to the market.

• But testing can never assure 100% bug free software. This might show the inconsistency and inefficiency of testing process or testing methodologies followed, it could also account the human errors in case of manual testing or script errors in case of automated testing.

• This directly impacts the quality of the software. Hence,

in order to improve the software quality, certain protocols and rules need to be laid down and complement the efficiency of the software.

•

Classification

1• Product Metrics• Process Metrics• Resource Metrics

2• Objective Metrics• Subjective Metrics

3• Primitive / Direct Metrics• Computed / Indirect Metrics

Product Metrics• Size Metrics• Complexity Metrics• Halstead’s Product Metrics• Quality Metrics

Product Metrics - Size• LOC• Function Points• Bang

Product Metrics - Complexity• Cyclomatic Complexity- v(G)

v(G) = e – n + 2• Extensions to v(G)

v’(G) = [l:u]• Knots• Information Flow

c = [procedure length] x [(fan-in) x (fan-out)]2

Product Metrics - Halstead’s Product

Metrics• Program Vocabulary

n = n1 + n2

• Program LengthN = N1 + N2

• Program VolumeV = N log2 n

Product Metrics - Quality Metrics

• Defect Metrics• Reliability Metrics• Maintainability Metrics

A Metrics ProgrammeA GQM Approach

References[1] Everald E. Mills “Software

Metrics”, SEI Curriculum Module SEI-CM-12-1.1, December 1988

[2] K.K. Aggarwal, Yogesh Singh, “Software Engineering”, New Age International Publishers, 3/e, 2008.