chapter2-unit1-software quality

7/31/2019 Chapter2-unit1-software quality

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JYOTSNA ANTHAL/CHAUHAN 1

Chapter2(Unit-1)

Software Quality


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Jyotsna Anthal/Chauhan 2

Quality:

Conformance to explicitly stated and agreed

functional and nonfunctional requirements,may be termed as qualityfor the software

product offered to customers/final users fromtheir perspective.


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Constraint of software Product Quality Assessment

Requirement specifications are made by BA& system analyst.

Testers may not have the direct access of the customer and willget info through requirement statements, queries answered etc.either from the customer or BA/SA.

There are few limitations of product quality assessment are: SW is virtual in nature: product cannot be seen, touched or

heard. Our normal senses & measuring instruments cannotcapable of measuring quality of SW .

SW is unique in nature: requirements, designs foundation,architecture, code etc. will be completely different fordifferent product. Way of SW design, coding & reusabilty

may differ from product to product.


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Huge communication gap between users of SW and

developers/testers of the product.5-8 agencies are involvedbetween these 2 ends and if an avg. communication loss of10% at each stage is considered the huge distortion isexpected from users perspective of requirement and actualproduct.

All aspects of SW cannot be tested fully as no. ofpermutation & combinations for testing all possibilities tend toinfinity. Exhaustive testing is neither feasible nor justifiable interms of cost.

SW program executesin same way when its executing someinstruction. An application with problematic code executeswrongly when it is executed. It makes a small defect turninto a major one as the probability of defect occurrence is100% when the part is executed.


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Customer is a KING


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Customer is the most imp. Person in any process ofdeveloping a product and using it.

All SW life cycle processes such as development,testing maintenance, etc are governed by customerrequirements.

A satisfied customer is an imp. Achievement for an organd is considered as an investment which may payback in short as well as in long term.

Org should implement some of the following measuresto achieve customer satisfaction.


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FACTORS DETERMINING SUCCESS

Internal customer and internal supplier:Internalcustomer satisfaction philosophy is guided by

principles of TQM.

External customer and external supplier :customers actually paying for getting their needsserved and External suppliers are the entities who are

external to the org and who are supplying to org


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QUALITY & PRODUCTIVITY RELATIONSHIP


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Quality improvement is concerned about the quality of theprocesses used for making such product not only product

quality.

If the processes of dev & testing are good, bad product will notbe manufactured in the first place.

It will reduce inspection, testing, rework and cost/price.

Quality must improve productivity by reducing wastage. Must

target for doing first-time right


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Improvement in Quality directly leads to improvedProductivity

Hidden factory producing scrap, rework, sorting, Repairand customer complaint is closed.

Effective way to improve productivity is to reduce scrapand rework by improving process

Quality improvements lead to cost reduction


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Employee Involvement in quality improvement:

management must include employees in quality

improvement programs at all stages.

Proper communication between management & employee is

essential

Employees participate & contribute in improvement process

Employee shares responsibility for innovation & qualityimprovement

(Assignment) difference between invention and innovation


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Different categories of requirements are:

Stated/Implied requirements

General/ specific requirements

Present/ future requirements

Must & must not requirements or primary req (P1)

Should be or should not be req. or secondary req(P2)

Could be or could not be req(P3)


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Organisation Culture


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Quality improvement programs are based on theability of the org to bring about a change in culture.

Philip crosby has prescribed Q improvement forcultural change.

Q culture of an org. is an understanding of theorganisations virtue (asset, good quality) of people,customer, suppliers and all stakeholders.

Q org are more quality conscious and q org is less

quality conscious.

Difference between Q org & q org


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Difference between Q org & q org.

Quality culture is Q Quality culture is not q

Believe in listening to customers &determine their requirements.

Assume that they know customerrequirements.

Concentrate on identifying cost of quality& focusing on it to reduce cost of failurewhich would reduce overall cost & price

Overlook cost of poor quality & hiddenfactory effect. They believe in more testingto improve product quality.

Doing things right for the first time & every

time is the motto of success.

Doing things again & again to make them

right is their way of working. Inspection,rework, scrap etc are essential

Concentrate on continuous/ continualprocess to eliminate waste and get betteroutput.

Work on the basis of finding & fixing theproblem.one time fix for each problemafter it occurs.

Believe in taking ownership of processes& defects at all levels. Try to assign responsibility of defects tosomeone else

Demonstrate leadership & commitment toquality & customer satisfaction

Believe in assigning responsibility forquality to others.

Shift i f f t Q


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Shift in focus from q to Q

As the org grows from q to Q there is a cultural change in

attitude of the management & employees towards quality &

customer. Above fig shows an improvement process where focus of

quality changes gradually.

Quality control

Quality assurance

Quality management

Q li l h (fi di fi i d f )


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Quality control approach (finding & fixing defects)

Org are at the higher end of q believe in finding and fixing

defects to the extent possible as the way to improve qualityof product before delivering it to the customer & achievingcustomer satisfaction.

Works on correction attitude involving defect fixing, scrap,rework etc.

Work on the philosophy that a product is good unless a

defect is found in it.

Huge testing teams, large investment in appraisal cost anddefect fixing cost followed by retesting and regression testing

are there.

Q alit Ass rance Approach (creation of Process


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Quality Assurance Approach (creation of Processframework)

Focus shifts from finding & fixing the defects to first

time right.

Org does investment in defining processes, policies,methods for handling various functions so that it can

incorporate a process approach for doing various things.

Becomes learning org. as it shifts its approach from Qcontrol to Q assurance.

Management approach shifts from corrections tocorrective actions through root cause analysis.

Starts working on preventive actions to some extent to

avoid potential defects.

Q lit M t A h


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Quality Management Approach:

3 types of systems : close, open and systems with semi permeableboundaries.

No defects in processes as they are optimized continuously, andproducts are delivered to the customer without deficiency.

Start working on defect prevention mechanism and continuous

improvement plans.

Org defines methods, processes & techniques for futuretechnologies & training programs for process improvement.

Management includes planning, organising, staffing, directing,coordinating and controlling to get the desired output.

Also involves mentoring, coaching and guiding people to do better

work.


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Characteristics of Software (assignment)


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SW cannot be sensed by common methods

of inspection or testing as it is virtual innature.it needs testing in real environment butnobody can do exhaustive testing by trying all

permutation and combinations.


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Software development Process

Th i h t b ild ft E h


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There are various approaches to build software. Eachapproach has some positive and negative points.

Waterfall development Approach/model

Iterative development Approach/model

Spiral development Approach/model

Prototyping development Approach/model

Rapid Application development Approach/model

Agile development Approach/model


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Types of Products

SW prod cts ha e some pec liarities defined as


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SW products have some peculiarities defined ascriticalities of SW. criticality of the SW defines, howmuch imp it is to the user/customer.

There are various schemes of grouping the productson the basis of criticality to the users. Few are below:

Life affecting products

Product affecting huge sum of money

Products which can be tested only by simulators

Other products.

Lif ff ti d t


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Life affecting products: Directly or indirectly affect human life are considered most

critical products in the world.

They come under the purview of regulatory and safetyrequirements, in addition to customer requirements.

Q req are more stringent and testing is critical for suchproducts.

This is grouped into 5 different categories:

Any product failure resulting into death of a person Any product failure may cause permanent disablement to a patients.

Any product failure may cause temporary disablement

Any product failure may cause minor injury

Other products which dont affect health or safety directly


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Product affecting huge sum of money

Direct relationship with loss of huge sum of money

Need large testing efforts and have many regulatory andstatutoryrequirements.

Examples- ecommerce and ebusiness softwares.- security,confidentiality and accuracy are some of the imp. Qualityfactors for such products.


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Products which can be tested only by simulators

Cannot be tested in real-time scenario but need simulatedenvironment.

Real time scenario is either impossible to create or may notbe economically viable.

Examples- products used in aeronautics, space research etc.


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Software Quality Management


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Software quality

American HeritageDictionary: a characteristic

or attribute of something


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Software quality

American Heritage Dictionary: acharacteristic or attribute of

something


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Software quality

Philip Crosby83:

conformance to requirements


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Software quality

Quality of design

Quality of conformance

Quality management involves management of all


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Quality management involves management of allinputs & processing to the processes defines so thatthe output from the process is as per defined quality

criteria. There are 3 levels of handling problem

Correction- condition where defects found in the product orservices are immediately sorted and fixed.

Corrective action-

situation where root cause analysis of the defects is done & actionsare initiated to remove the root causes so that the same defect

doesn't recur again. Operations management group is responsible for corrective action

(identification & implementation)

Preventive actions-


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Preventive actions-

means there are potential weak areas where defect has notbeen found till that point, but there exists a probability offinding a defect.

Similar scenarios are checked and actions are initiated sothat other potential defects can be eliminated before theyoccur.

Senior management is responsible for preventive actions.

QM approach where an org takes preventiveaction so there is no defects at first place.


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WHY SW HAS DEFECTS?

Huge communication losses between entities

Development people are more confident about their technicalcapabilities and do not consider that they can makemistakes.

Requirement changes are very dynamic.

Technologies are responsible for introducing few defects.

Customer may not be aware of all requirements.


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PROCESSES RELATED TO SW QUALITY

VISION

STRATEGY 1

GOAL1,2,3,4

OBJECTIVE1,2,3

POLICY1,2

MISSION1

GOAL5,6,7

GOAL8,9,10,11

STRATEGY2,3 STRATEGY4,5,6,7

OBJECTIVE7,8,9,10

OBJECTIVE4,5,6

POLICY6,7POLICY3,4,5

MISSION3MISSION2

VISION


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VISION

Established by the policy management.

Defines what org wishes to achieve in the given time horizon.

to become a billion dollar company within 3 years Every org must have a vision statement, clearly defining with

respect to time span.

MISSION

Several initiatives defined as mission which will be helpful inrealising its vision.

Missions are expected to support each other to achievevision put by management.

Missions may have different life span and completion dates.

Policy


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Policy

intent of management.

Many policies will define a way of achieving missions.

Ex- security policy, quality policy and human resource devpolicy. Tells us way of doing business as defined by seniormanagement.

Helps employees, suppliers and customers to understand

the thinking and Objectives

Defined quantitatively

Defines an expectation from each mission and can be used

to measure the success/failure of it. Must be expressed in numerals along with time period.

Every mission must have one objective.

Strategy


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Strategy

Defines the way of achieving a particular mission.

Involves the actions required to realise the mission and way ofdoing things.

Policy is converted into actions.

Must have a time frame and objectives along with goalsassociated with it.

Goals

Defines the milestones to be achieved to make the missionsuccessful.

Values

Defined as the principles, or way of doing business as perceived

by management.

Treating customers with courtesy can be a value for an org.

Manner in which a n org think and behave is governed by values itbelieves in.


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Quality Management System

Structure

QMS of a typical organisation


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Q S o a typ ca o ga sat o

Quality Policy

Quality Objectives

Quality Manual

QualityProcesses/

QualityProcedures

Workinstruction

Guidelines/standards

Formats/Templates

Every org has different QM Structure depending upon its needs and


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circumstances.

Ist Tier (Quality Policy):

Sets the wish, intent and direction by the management about

how activities will be conducted by the org.

Basic framework on which the Q temple rests.

2nd Tier (Quality Objectives:

Are measurements established by the management to defineprogress and achievements in numerical way.

Achievement of these objectives must be compared withplanned levels and deviations must be acted upon.

3rd Tier (Quality Manual) Termed as policy manual, established & published by the

management of the organisation.

Sets a framework for other process definitions

Foundation of Quality planning at organisational level


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PILLARS OF QUALITY MANAGEMENT

SYSTEM

Quality Processes/ Quality Procedures Work instruction


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y y Are defined at org level by the functional area experts

Processes Act as an umbrella process definitions may different fordifferent projects and functions.

Guidelines/ standards Are used by an orgs project team for achieving quality goals for the

products & services delivered to customers.

Guidelines are suggested ways of doing things where asstandards aremandatory ways of doing things

Guidelines may be overruled but over ruling of standards is apunishable offence

Guidelines may or may not be written but standards must bewritten to avoid any misunderstanding.

Both may need revision from time to time.

Formats/ Templates- used for tracking a project, function and dept info. Act as checklist to

maintain consistency across the project in the org.

If made compulsory are considered as standard where as if they areindicative or suggestive, they are guidelines.

Templates are mandatory while Formats are suggestive in nature.


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Important Aspects of Quality

Management

Quality planning at organisational level


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Q y p g g

Quality planning at project level

Resource management

Work environment Customer related processes

QMS document and data control

Verification and validation SW project management

SW configuration management

SW metrics and measurement SW quality audits

Information security management

Management Review

Quality planning at organisational level:


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Quality planning at organisational level:

Includes establishing missions, policies andstrategies at org level along with objectives & goals to

achieve vision

Quality planning at Project level: Strategic level quality plans with details of responsibilities

and actions.

Project plan must define all aspects of quality at projectlevel

Quality objectives of the project may be inherited fromorganisation level objectives or

May be defined separately for the project

Resource management:


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g

Org should use good inputs as required by quality planningso the output of the processes match the organisations

business plan.

Includes people, machines, materials and methods as thebasic resources.

Good processes and good technology need good people toperform work and achieve planned results.

Work environment:

An imp input for a good product &

Can help an org to build on its strength

Two components- external and internal environment.

Customer Related Processes:


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Must be analysed for their capability in servicing customers &achieving customer satisfaction.

Requirement analysis, designing, project processes, productdelivery and other processes related to the customer mustbe analysed.

QMS document and data control QMS is defined on the basis of some quality standards

/models

There may be Specific customer requirements for different

standards & models which help an org in defining its ownQMS.

Statistical process control and data management areessential for continuous improvement of processes.

Verification & validation:


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V&V are performed by an org at each level of development

and for each activity.

Verification defines the processes used to build the productcorrectly.

Verification includes management reviews and technicalreviews (such as technical review and project plan review)

Validation ensures that the right product has been built

Validation involves different kinds of testing (unit testing &system testing) to ensure the work product meets the

predefined acceptance criteria.


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End of chapter 2

chapter2-unit1-software quality

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