1 QUALITY CONTROL QUALITY ASSURANCE Controlling the software - - PDF document

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24.3.2004 Software Engineering 2004 Jyrki Nummenmaa 1

SOFTWARE ENGINEERING SOFTWARE QUALITY

• Today we talk about software process quality and

certification

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SOFTWARE QUALITY - QUALITY COMPONENTS

• Objective quality component: properties that can

be measured or approximated objectively

• Subjective quality component: customer

satisfaction (”What does the product feel like?”)

• Other: features which can not be (even

subjectively) evaluated at the time. This is related with future events which can not be predicted - unexpected circumstances, changes, etc.

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THE QUALITY SYSTEM

• Quality control - controlling the way things are

done

• Quality assurance - making sure quality is

achieved

• Quality policy
• Quality planning
• Quality improvement
• These terms come from the standard ISO 8402

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THE QUALITY SYSTEM (cont’d)

• The quality system of a company is simply the way

the company works and it covers all areas of activity.

• Therefore, a quality system always exists. It may

be documented or not.

• However, in the long run in a big company it

makes a major difference, if the management takes quality seriously and knowingly emphasizes it in all activities.

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QUALITY CONTROL

• Controlling the software development process
• Standards for the development process, e.g.
• well-defined phases
• checklists
• reviews: what and when
• organisational standards
• Visibility and bookkeeping of the development

process

• Standards for software code and documentation, e.g.
• naming and style
• document skeletons and formats
• different kinds of review and feedback forms

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QUALITY ASSURANCE

• Improving software quality by monitoring the

products (software) and process

• Ensuring full compliance with the standards for

products and process

• Ensuring that any inadequacies in the product and

process (and standards) are brought to management’s attention.

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QUALITY ASSURANCE - PREREQUISITES

• Top management commitment
• The quality assurance organisation must be

independent from the development organisation.

• The quality assurance organisation must be

properly staffed.

• The quality assurance organisation must co-
• perate properly with the development
• rganisation. Quality must be seen as a common

goal.

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PROCESS QUALITY METRICS

• Actual vs. estimated time and cost
• Number of faults detected
• Phase of the project when faults were found
• Productivity (e.g. lines of code / man-month)
• Quality expenses (e.g. repairs required after

delivery)

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QUALITY REVIEW TYPES

• Design or program inspections/audits. These are

commonly driven by a checklist of possible errors.

• Management reviews. These are intended to

provide information for the management about the

• verall progress of the software project.
• Quality reviews. The work of an individual or a

team is reviewed by a panel made up of project members and technical management.

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A GENERAL SCHEME FOR REVIEWS

• Select the review team.
• Arrange the place and time.
• Distributed the documents.
• Hold the review.
• Note the actions and complete the review forms.

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POSSIBLE ACTIONS FOR FINDINGS IN REVIEWS

• No action. Some kind of an anomaly was found,

but it was not cost-effective to fix it.

• Refer for repair. The team or individual in charge
• f the product has to correct the fault.
• Reconsider the overall design. It may be more

reasonable to fix other components of the system to solve the problem which was found.

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INSPECTIONS / AUDIT SESSIONS

• The ”Fagan method” - named after an IBM

employee who pioneered the technique

• All types of defects are noted - not just logic or

function errors.

• Inspections can be carried out by collagues at all

levels except the very top.

• Inspections are carried out using a predefined set
• f steps.
• Inspection meetings do not last for more than two

hours.

• The inspection is lead by a moderator who has a

specific trainging in the technique.

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INSPECTIONS / AUDIT SESSIONS (continued)

• The other participants have defined roles. For

example, one person will act as a recorder and note all defects found and another will act as a reader who takes the other participants through the document under inspection.

• Checklists are used to assist the fault-finding

process.

• Material should be inspected at an optimal rate of

about 100 lines per hour.

• Statistics are maintained so that the effectiveness
• f the inspection process can be monitored.

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A CHECKLIST FOR REVIEW EVALUATIONS

• Is material complete (and does it meet the

standards)?

• Was material distributed on time?
• Are applicable standards referenced and available?
• Were attendees prepared to contributed?
• Did evaluation start on time?
• Were number of defects identified?
• Was review conducted per standard protocols?
• Were entrance criteria met?
• Were exit criteria met?

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A CHECKLIST FOR REVIEW EVALUATIONS (cont’d)

• Are all issues scheduled for resolution?
• Are interface issues coordinated?
• Is disposition of all defects complete?
• Were HCI, testing, maintenance, and tools

considered?

• Were quality attributes reported?
• Has trace of defects been initiated?

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SOFTWARE QUALITY CIRCLES

• A Japanese practice.
• A quality circle is a group of four to ten volunteers

working in the same area who meet for, say, an hour a week to identify, analyse and solve their work-related problems.

• One of the group is a group leader and one

(maybe from outside) is a facilitator giving advice.

• Training is required, and so is full support from the

management.

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PROBLEM SOLVING BY SOFTWARE QUALITY CIRCLES

• Identify a list or problems and choose one.
• Clarify the problem.
• Identify and evaluate the causes.
• Identify and evaluate the solutions.
• Decide on the solution.
• Develop an implementation plan.
• Present the plan to the management.
• Implement the plan.
• Monitor the plan.
• Consider wider apllicability of solution.
• Restart from choosing another problem.

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ISO 9000

• Series of standards for general use in different

fields of industry.

• ISO 9001 is for companies with product

development and production.

• Separate certification organisations give

certification for companies which fulfill the requirements of the standards.

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INGREDIENTS OF ISO 9001

• Management responsibility
• Quality system
• Contract review
• Design control
• Document control
• Purchasing
• Purchaser supplied control
• Product identification adn traceability
• Process control
• Inspection and testing

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INGREDIENTS OF ISO 9001 (continued)

• Inspection, measuring and test equipment
• Inspection and test status
• Control of nonconforming product
• Corrective action
• Handling, storage, packaging and delivery
• Quality records
• Internal quality audits
• Training
• Servicing
• Statistical techniques

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AN OVERVIEW OF ISO 9001 REQUIREMENTS

• The management must define and document the

policy concerning quality and must ensure that this policy is communicated to all levels of the

• rganisation.
• All quality control procedures must be

documented.

• All contracts to supply goods or services should

contain mutually agreed requirements that the developer is capable of delivering.

• There should be procedures to approve design and
• ther documentation.

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AN OVERVIEW OF ISO 9001 REQUIREMENTS (continued)

• Where components of the system to be supplied to

the client are obtained from third parties there must be procedures to ensure, check, and maintain the quality of these components.

• Individual products should be identifiable as

should their components.

• The process by which the final product is created

should be planned and monitored.

• Inspection and testing should take place during

the development phase, at its completion and before delivery. Tests and inspections should also be carried out on components obtained from third parties.

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AN OVERVIEW OF ISO 9001 REQUIREMENTS (continued)

• The equipment used in the production process

itself should be properly controlled with respect to quality.

• The testing status of all components and systems

should be clearly recorded all times.

• Care must be taken to ensure that items which are

known to be defective are not inadvertently used.

• When a defect is detected, measures must be

undertaken to remove the defective part and to ensure that the defect does not occur again.

• Satisfactory procedures must be in place to deal

with correct handling, storage, packaging, and delivery of the product.

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AN OVERVIEW OF ISO 9001 REQUIREMENTS (continued)

• Sufficient records must be maintaned to

demonstrate that the quality system is working satisfactorily.

• The software quality management system should

be audited on a regular basis.

• Servicing and supprt activiies must be subject to

the quality management system.

• The developer must establish appropriate

statistical techniques to verify the acceptability of the final product.

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CERTIFICATION (for standards like ISO 9001)

• The company familiarises itself with the standards.
• The company applies for the certification.
• The certification organization inspects the

company (based on documents which it requires from the company).

• An evaluation meeting is held with representatives

from both the company and the certification

• rganisation.
• If necessary, some corrective actions are

performed.

• A certification is given to an accepted company.
• Re-evaluations will be performed.

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GENERAL CONCLUSIONS

• The development of a quality system requires

changes and changes create resistance.

• Be realistic.
• Quality depends a lot on attitudes.
• Internal and management motivation is essential.
• Small steps can be the best way forward.