Sqa Lectures Ppt

8/3/2019 Sqa Lectures Ppt

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Definition of QUALITY

- Quality is physical or nonphysical characteristics that constitutes

that basic nature of a thing is one of its distinguishing features.(Webster’s New World Dictionary)

- Quality as applied to the products turned out by industry means thecharacteristics or group of combination of characteristics which

distinguishes one article from another, or the goods of onemanufacturer from those of his competitors, or one of grade forproduct from certain factory from another grade turned out by thesame factory. (Radford)

- Quality is fitness for use. (Juran)



…cont.

- There are two common aspects of quality, one of these has to do withthe consideration of quality of a thing as an objective reality independentof the existence of man. The other has to do with what we think, feel,

or sense as a result of the objectives reality- this subjective side ofquality is closely linked to value.(Shewart )

- Quality is conformance to requirements (clearly stated) (Crosby)

- Quality should be aimed at the needs of the consumer, present and

future. (Deming )- Quality is total composite product and service characteristics ofmarketing, engineering, manufacture, and maintenance through whichthe product and service in use will meet the expectation of thecustomer. (Feigenbaum)

- Product quality encompasses those characteristics which the productmust possess if it is to be used in the intended manner. (Mizuno)



DAVID GARVIN’S FIVE APPROACHES TO QUALITY

1. Transcendent Approach: Quality is recognized through learning and

experience defined in terms of innate excellence.

2. Product-Based Approach: Quality is precise and measurable it can be

ranked on various attributes and is an inherent part of the product.

3. User-Based Approach: Quality reflects personal, idiosyncratic view,

reflected in consumer demand curves in marketing, quality is theideal combination of attributes for maximizingconsumer satisfaction.

4. Manufacturing-Based Approach: Focus on engineering and

manufacturing practices; quality is defined as conformance

specifications; reduce costs by reducing the number of deviations.

5. Value-Based Approach: Quality is defined as performance or

conformance at an acceptable cost this is the notion of“affordable excellence”



DAVID GARVIN’S EIGHT DIMENSIONS OF QUALITY

1. Performance – Primary operating characteristics; combines product and

user-based approach relationship between performance and qualityreflects individual reactions top objectives characteristics.

2. Features – The “bells and whistles” of the product; secondary to basic

functioning and less central users.

3. Reliability – Probability of the product failing within a given time period,

more relevant to durable goods

4. Conformance – Degree design and operating characteristics match

specification; related to reliability in the factory measured by

frequency of defects (rework and repair) and in the field by servicecalls and repairs under warranty.



DAVID GARVIN’S EIGHT DIMENSIONS OF QUALITY

5. Durability – Measure of product life, technically, as the amount of

use, before it deteriorates and economically, in terms of repaircosts trade-off between repair and replacement (both personal andeconomic costs)

6. Service ability – Speed courtesy, and competence of repair,

subjective and objective aspects most consumer equate rapidrepair with higher quality.

7. Aesthetics – Subjective assessment of look, feel, or sound of the

product; reflects individual preferences.

8. Perceived Quality – Indirect measures of quality such as brand

name, image, often used when other information is unavailable.



FIVE PARADIGMS OF QUALITY

1. Custom-Craft Paradigm – In this paradigm, there is a clear

communication between the craftsman and customer resulting infocus on the product and product performance relative to thedemands. The product is made exactly the way the buyer wants.Example of this pattern are found in tailor’s shop, furniture supplier,

bank loans etc.

2. Mass Production Paradigm- This paradigm developed post-

mechanization. Here the focus is on production rates, and the directinvolvement of the customer is not there although the product isdefined with customer in mind. Product performance is relativelylow here and there is generation of rework and scrap. The delivery

times is typically low as the sales happen from stocks being held.Service organization in this paradigm are labor intensive.Examples of this pattern are found in automobile parts, etc.



…cont.

3. Statistical Quality Control Paradigm- This similar to mass

production paradigm except that the focus is more on the process.Together with mechanized production statistical process control isapplied in the process due to which there is less generation of scrap

and rework, and the production cost goes down. Here the product aredesigned and build, statistical techniques are used and then thecustomers are created. Examples of this pattern are found inautomobile parts, electronic components, etc.

4. Total Quality Management Paradigm- Together with mass

production and statistical techniques. This paradigm focuses oncustomer and supplier. Here the production lines are same as massproduction paradigm but the customer plays a part in productdefinition, creation and performance evaluation. Employeeinvolvement and empowerment, customer-focus, continuous

improvement, top management commitment training team work, areits key tenets. The result is high quality product, low cost and fastdelivery. Rework and scrap are reduced substantially. In short,customers tell what they want and the product is delivered usingproactive and reactive quality strategies. Examples can be found in

products/services from TQM companies.



…cont.

5. Techno-Craft Paradigm- This paradigm is a new frontierof quality that seeks to emulate the custom-craft paradigm

in performance while reducing the cost and delivery time.This paradigm requires high level of product and processflexibility. Customers get exactly what they want. Therequirement here is of integration of machine, men andautomation. Computer aided design and manufacturing

would be of great help here. Each unit designed andbuild the way the customer wants it to build. Thisparadigm is being tried out in apparel and softwareindustry.



To produce goods and services of consistent quality and costs, threetypes of quality are recognized. These are:

- Quality of Design

- Quality of Conformance

- Quality of Performance

TYPES OF QUALITY



1. QUALITY OF DESIGN

Here the focus is to develop products and services that are suited to thecustomer’s needs at a given cost. Quality of design begin with the consumer

research, sales call analysis and leads to determination of products that meet

customer requirements. This is followed by the development of adequatespecifications.

Communicatespecifications

Determines Needs viaConsumer Research

and Sales/Service Call

Analysis

Concept andSpecifications

Suppliers Organization Customers



Refers to the extent to which a firm and its suppliers can produceproducts with a predictable degree of uniformity and dependability, at a givencost, in keeping with the quality requirement determined in the quality ofdesign study. Once the specifications are determined via a quality of design

study, the organizations must continuously strive to improve these specifications.

2. QUALITY OF PERFORMANCE

CommunicateSpecifications Determine

Needs

Conformance

Organization

Suppliers Customers



3. QUALITY OF PERFORMANCE

Quality of performance studies focus on determining how the qualitycharacteristics determined in quality of design, and improve and innovated inquality of conformance studies are performing in the market place. The majortools used here are study of after-sales service-call analysis. This tools evaluatewhy consumers like or dislike a product.

CommunicateSpecifications

DetermineNeeds

Redesign

Organization

Suppliers Customers



What is a software?

computer programs(the code) – these are needed to activate the computer to performthe required application.

- defined software as computer programs, procedures, andassociated documentation and data pertaining to the operation of a computer system

IEEE (Institute of Electrical and Electronics Engineers)

FOUR COMPONENTS OF SOFTWARE

data necessary for operating the software system- essential data includingparameters that adapt the software to the needs of the specific user are necessaryfor operating the software.

Documentation-The development documentation allows efficient cooperation andcoordination among development team members. User’s documentation provides a

description of the available application and the appropriate method for their use.The maintenance documentation provides the maintenance team with all therequired information about the code, and the structure and tasks of each

software module.

procedures-these are required o define the order and schedule in which the programsare performed, the method employed and the person responsible for such activities.



SOME SOFTWARE CHARACTERISTICS

1. Software is developed or engineered,it is not manufactured in the classical sense.

2. Software doesn’t “wear out”.

3. Most software is custom-built, rather than

being assembled from existing components.



What is software quality?

IEEE defined software quality as:

- The degree to which a system, component, or processmeets specified requirements.

- The degree to which a system, components, or processmeets customer needs or expectations.

Quality means conformance to requirements.

- Quality consists of those product features which meet the needsof customers and thereby provide product satisfaction.

- Quality consists of freedom from deficiencies.

***Pressman defined software quality as a conformance to explicitly statedfunctional and performance requirements, explicitly documented developmentstandards, and implicit characteristics that are expected of all professionallydeveloped software.



What is software quality assurance?

IEEE defined software quality assurance as:

1. A planned and systematic pattern of all actions necessary to provideadequate confidence that an item or product conforms to establishedtechnical requirements.

2. A set of activities designed to evaluate the process by which the productsare developed or manufactured.

3. A systematic, planned set of actions necessary to provide adequateconfidence that the software development process or the maintenanceprocess of a software product conforms to established functional technical

requirements as well as with the managerial requirements of keeping theschedule and operating within the budgetary confines.



Quality Control vs. Quality assurance

Quality control – is defined as “a set of activities designed

to evaluate the quality of a developed or manufacturedproduct. Quality control inspection and other activitiestake place as the development or manufacturing of theproduct is completed yet before the product is shipped

to the client.

Quality assurance- the objective is to minimize the cost ofguaranteeing quality by a variety of activities performedthroughout the development and manufacturing processes

or stages. These activities prevent the cause of errors, anddetect them and correct them early in the development

process.



SOFTWARE ERRORS, FAULTS AND FAILURES

Software errors- are made by programmer that can begrammatical error or logical error.

Software faults-not all software errors become software faults.

These are errors which will not affect the functionalityof the software unless the fault was activated.

Software failures- the origin of software failures lies in asoftware errors. It disrupts the use of the software.



NINE(9) CAUSES OF SOFTWARE ERRORS

1. Faulty requirements definition -erroneous definition of requirements-absence of vital requirements

-incomplete definition of requirements-inclusion of unnecessary requirements

2. Client-developer communication failures- misunderstanding of the clients instructions as stated in the

requirement document.- misunderstanding of the clients requirements changes

presented to the developer in written form during the

development period.- misunderstanding of the clients requirements changes

presented to the developer orally during the development period.- misunderstanding of the clients responses to the design

problems presented to the developer. Deliberate deviationsfrom software requirements.

cont



…cont

3. Deliberate deviations from software requirements- The developer reuses software modules taken from an earlier

project without sufficient analysis of the changes and

adaptations needed to correctly fulfill all new requirements.- Due to time or budget pressures, the developer decides toomit part of the required functions in an attempt to cope withthese pressures.

- Developer-initiated, unapproved improvements to the software,

introduced without clients approval.

4. Logical design errors- Definitions that represent software requirements by means of

erroneous algorithms.- Process definitions that contain sequencing errors

- Erroneous definition of boundary conditions.- Omissions of required software system states.- Omission of definitions concerning reactions to illegal

operation of the software system.

cont



…cont.

5. Coding errors

6. Non-compliance with documentation and coding instructions

7. Shortcoming of the testing process- Incomplete test plans leave untreated portions of the software.- Failures to document and report detected errors and faults.- Failure to promptly correct detected software faults.

- Incomplete correction of detected errors due to negligence

or time pressures.

8. Procedure errors

9. Documentation errors

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