smqa unit i

Software Metrics and Quality Assurance

Reference Books• 1) Software Metrics – A Rigorous & Practical Approach, 2E

– By:- Norman E Fenton & Shari Lawrence Pfleeger– Publication :- Thomson Learning.– (Chapter 1,2,3,7,8,9,10,12 ) – Syllabus covered I,II,III Units

2) Software QualityBy :- Garry Marliss and Ben-Menachem

– Publication :- Thomson Learning.– (Chapter,7,8,9,19 ) – Syllabus covered IV Unit

Mr. M. E. Patil S.S.B.T COET, Bambhori

• Software Engineering –A Practitioners approach, fifth edition.

By :- Roger S Pressman.Chapters 27 28,29(Syllabus Covered:- V unit)

Mr. M. E. Patil S.S.B.T COET, Bambhori

Software Metric and Quality Assurance

• Software Metric:– It is the combination of the various attributes of

the software.– Attributes of the software are

• Length • Functionality• Reuse• Number of faults

Mr. M. E. Patil S.S.B.T COET, Bambhori

• Quality Assurance:-– Fitness of purpose– Conformance to the given specifications– Degree of excellence– Timeliness

Mr. M. E. Patil S.S.B.T COET, Bambhori

Measurement in everyday life

• Without measurement technology cant function

• Examples of Measurement – Radar System– Medical System– Whether forecasting system – Price act as value of an item– Journey from jalgaon to Mumbai

Mr. M. E. Patil S.S.B.T COET, Bambhori

Measurement helps to

• Understand our world• Interact with the surroundings• Improve our lives.

Mr. M. E. Patil S.S.B.T COET, Bambhori

•What is Measurement ?

Mr. M. E. Patil S.S.B.T COET, Bambhori

• Measurement is the process by which numbers or symbols are assigned to attributes of entities in the real world, so as to describe them according to the clearly defined rules.

Mr. M. E. Patil S.S.B.T COET, Bambhori

• An Entity :- an object (person or object)an event (Journey or the testing process)

Attribute:- It is the feature or property of an entity.

e.g. area or color of the room, cost of the journey,

Mr. M. E. Patil S.S.B.T COET, Bambhori

• Measurement can be called as quantification• There are two types of quantification

– Direct and Indirect quantification– Measurement is direct quantification

• E. g. Height of a tree , length of software

– Calculations are indirect quantification• E.g. Area of room = Length * Breadth

Mr. M. E. Patil S.S.B.T COET, Bambhori

Measurement in software Engineering

• Software engineering Activity includes – Managing– Costing– Planning– Designing– Modeling– Analyzing– Implementing– Testing and maintaining

Mr. M. E. Patil S.S.B.T COET, Bambhori

• As software engineering focuses on implementing the software in controlled and scientific way.

• To do this, all the above activities must be understood then we can control them and further we can improve.

Mr. M. E. Patil S.S.B.T COET, Bambhori

Neglecting measurement in software engineering

• We fail to set measurable targets for our software products.

• We fail to understand and quantify the cost of software products.

• We can’t quantify the quality of the product we produce

• We can’t find out the improvements in out product development

Mr. M. E. Patil S.S.B.T COET, Bambhori

Objectives of software measurement

• Measurement is needed for assessing the status of our – Projects– Products– Processes– Resources

Mr. M. E. Patil S.S.B.T COET, Bambhori

Information required to understand and control software development

• Form Managers Perspective– What does each process cost ?– How productive is the staff ?– How good is the code being developed ?– Will the user be satisfied with the product ?– How we can improve ?

Mr. M. E. Patil S.S.B.T COET, Bambhori

• From Engineers Perspective:-– Are the requirements testable ?– Have we found all the faults ?– Have we meet our product or process goals ?– What will happen in future ?

Mr. M. E. Patil S.S.B.T COET, Bambhori

Representational theory of Measurement

• The data we obtain as measure should represent the attribute of the entities we observe and manipulation of data should preserve relationship that we observe among the entities

• It consists of – Empirical Relation– Rules of Mapping– Representation condition

Mr. M. E. Patil S.S.B.T COET, Bambhori

Empirical relation

• We normally understand things by comparing them instead of assinging them numbers.

• Avinash is tall - ‘is tall’ is the unary relation• Avinash is taller than Sushant.

– Taller than is the binary relation

Mr. M. E. Patil S.S.B.T COET, Bambhori

Rules of Mapping

• The real world is the domain of mapping and mathematical world is the range.

• When we map the attributes to a mathematical system, we have many choices for the mapping and the range.– E.g. To measure person height.

Mr. M. E. Patil S.S.B.T COET, Bambhori

The representation condition

• The representation condition states that a measurement mapping M must map the entities in to numbers ans empirical relations into the numerical relations in such a way that the empirical relations preserve and are preserved by the numerical relations.

• For taller than in empirical relation is mapped to symbol > in numerical relation.

Mr. M. E. Patil S.S.B.T COET, Bambhori

• A is taller than B iff M(A) > M(B).• This statement implies that

– When ever A is taller than B then M(A) must be bigger number that M(B)

Mr. M. E. Patil S.S.B.T COET, Bambhori

• A is tall• When M(A) > 5.5’ i.e. average height of

common man

Mr. M. E. Patil S.S.B.T COET, Bambhori

Mr. M. E. Patil S.S.B.T COET, Bambhori