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Chapter - 06
Software Quality Management
12 Marks
01. Basic Quality Concepts:
Quality(Q)
Quality control (QC)
Quality assurance (QA)
Cost of quality
02. Quality
We define quality as a characteristic or attributes of something. eg. programs include complexity, number of
functions, line of code etc.
Two kinds of quality are:
Quality of conformance: the degree to which the design specifications are followed during manufacturing.
If implementation follows the design, resulting system meets its requirements and performance goals,
conformance quality will be high.
User satisfaction= compliant product+ good quality+ delivery within budget and schedule.
03. Quality control:
Quality control involves series of inspections, reviews, tests used throughout the process.
It includes a feedback loop to the process.
A key concept of quality control is that all work product have defined, specifications are compared and
feedback loop is essential to minimize the defects produced.
04. Quality assurance:
Quality assurance assess the effectiveness and completeness of quality control activities.
The goal of Quality assurance is to provide management with the data necessary about product quality,
gaining confidence that product quality is meeting its goal.
If not ,its managements responsibility to address the problem and apply the necessary resources to resolve
quality issues.
05. Cost of quality:
It is divided into:-
Prevention cost- includes quality planning, formal technical reviews, test equipment and testing.
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Appraisal cost- includes process inspection, equipment calibration, maintenance.
Failure cost-
Internal failure cost- when we detect a defect in our product prior to shipment. It includes rework, repair etc.
External failure cost- Defects found after the product has been shipped to the customer. It includes
resolution, replacement, help line support and warranty work.
06. Software Quality Assurance-SQA
Software quality assurance is composed of a variety of tasks associated with two different aspects the
software engineers who do technical work and an SQA group that has responsibility for QA planning,
oversight, record keeping, analysis, and reporting.
Software engineers address quality (and perform quality assurance and quality control activities) by applying
solid technical methods and measures, conducting formal technical reviews, and performing well-planned
software testing.
07. Activities of SQA
1) Prepare an SQA plan for a project:- The plan is developed during project planning and is reviewed by all
interested parties.
• The plan identifies
> evaluations to be performed
> audits and reviews to be performed
> standards that are applicable to the project
> procedures for error reporting and tracking
> documents to be produced by the SQA group
> amount of feedback provided to the software project team.
2) Participate in the development of the project’s software process description:-
The software team selects a process for the work to be performed.
The SQA group reviews the process description for compliance with organizational policy, internal
software standards, externally imposed standards (e.g., ISO-9001), and other parts of the software project
plan.
3) Review software engineering activities to verify compliance with the defined software process.
• The SQA group identifies, documents, and tracks deviations from the process and verifies that corrections
have been made.
4) Audits are designed for s/w work products to verify compliance with those defined as a part of process.
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• Verify that corrections have been made and periodically reports the results of its work to the project
manager.
Ensure that deviations in software work and work products are documented and handled according to a
documented procedure. Deviations may be encountered in the project plan, process description, applicable
standards, or technical work products.
Records any noncompliance and reports to senior management. Noncompliance items are tracked until they
are resolved.
08. Concept of Statistical SQA
Statistical SQA reflects growing trend throughout industry to become more quantitative about quality.
Information about s/w defects is collected and categorized.
Tracking fundamental causes of defects.(design error, violation of standard, poor communication, inaccurate
documentation)
use of pareto principle.(80% of defects can be traced to 20%of all possible causes)
Once the causes have been identified, move to correct the problem that have caused the defects.
09. Quality Evaluation Standards
01. Six Sigma for s/w engineering.
02. ISO:9000 for software
01. Six sigma for software
Six Sigma is the most widely used strategy for statistical quality assurance in industry today. Originally
popularized by Motorola in the 1980s.
The Six Sigma strategy - is a rigorous and disciplined methodology that uses data and statistical analysis to
measure and improve a company's operational performance by identifying and eliminating defects in
manufacturing and service-related processes.
The term Six Sigma is derived from six standard deviations instances (defects) per million occurrences
implying an extremely high quality standard
i. DMAIC and DMADV
Six sigma methodology defines three core steps:-
These core and additional steps are sometimes referred to as the DMAIC (Define, Measure, Analyze, Improve,
and Control) method.
Define customer requirements and deliverables and project goals via well-defined methods of customer
communication.
Measure the existing process and its output to determine current quality performance (collect defect
metrics).
Analyze defect metrics and determine the vital few causes.
• If an existing s/w process is in place, but improvement is required, six sigma suggest two additional steps:-
Improve the process by eliminating the root causes of defects.
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Control the process to ensure that future work does not reintroduce the causes of defects.
If an organization is developing a software process (rather than improving an existing process), the steps are
as follows:-
Design the process to avoid the root causes of defects and to meet customer requirement.
Verify that the process model will avoid defects and meet customer requirement.
The variation is sometimes called as DMADV (Define, Measure, Analyze, Design and Verify method.)
02. ISO 9000 for software:
International set of standards for quality management.
Quality standards and procedures must be documented in an organizational quality manual
An external body is often used to certify that the quality manual conforms to ISO 9000 standards
10. ISO principles/standards with benefits.
1. Customer focus
2. Leadership
3. Involvement of People.
4. Process approach5. System approach 6. Continual improvement.
5. Factual approach to decision making
6. Mutually beneficial supplier relationships.
11. CMMI:
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Definition- Capability Maturity Model Integration (CMMI) is a process improvement approach that helps
organizations improves their performance.
CMMI (Capability Maturity Model Integration) is a proven industry framework to improve product quality and
development efficiency for both hardware and software. Objectives of CMMI:
Specific Objectives
> Establish Estimates
> Develop a Project Plan
> Obtain Commitment to the Plan
Generic Objectives:
> Achieve Specific Goals
> Institutionalize a Managed Process
>Institutionalize a Defined Process
> Institutionalize a Quantitatively Managed
Process
>Institutionalize an Optimizing Process
12. CMMI maturity levels:
Level 1: Initial. The software process is characterized as adhoc and occasionally even chaotic. Few processes
are defined, and success depends on individual effort.
Level 2: Repeatable. Basic project management processes are established to track cost, schedule, and
functionality. The necessary process discipline is in place to repeat earlier successes on projects with similar
applications.
Level 3: Defined. The software process for both management and engineering activities is documented,
standardized, and integrated into an organization wide software process. All projects use a documented and
approved version of the organization's process for developing and supporting software. This level includes all
characteristics defined for level2
Level 4: Managed. Detailed measures of the software process and product quality are collected. Both the
software process and products are quantitatively understood and controlled using detailed measures. This
level includes all characteristics defined for level3
Level 5: Optimizing. Continuous process improvement is enabled by quantitative feedback from the process
and from testing innovative ideas and technologies. This level includes all characteristics defined for level 4.
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CMMI Vs ISO
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13. McCall’s Quality factors:
The factors that affect S/W quality can be categorized in two broad groups:
Factors that can be directly measured (defects uncovered during testing)
Factors that can be measured only indirectly (Usability and maintainability)
The S/W quality factors shown above focus on three important aspects of a S/W product:
i. Its operational characteristics ii. Its ability to undergo change iii. Its adaptability to new environments
14. The various factors of quality are:
Correctness: The extent to which a program satisfies its specs and fulfills the customer‘s mission objectives.
Reliability: The extent to which a program can be expected to perform its intended function with required
precision.
1.Efficiency: The amount of computing resources and code required to perform is function.
2.Integrity: The extent to which access to S/W or data by unauthorized persons can be controlled.
3.Usability: The effort required to learn, operate, prepare input for, and interpret output of a program.
4.Maintainability: The effort required to locate and fix errors in a program.
5.Flexibility: The effort required to modify an operational program.
6.Testability: The effort required to test a program to ensure that it performs its intended function.
7.Portability: The effort required to transfer the program from one hardware and/or software system
environment to another.
8. Re usability: The extent to which a program can be reused in other applications- related to the
packaging and scope f the functions that the program performs.
9. Interoperability: The effort required to couple one system to another.
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