The approach
Software Quality Models
Structures
Of Quality
What is Quality?
Drazen Milicic
Quality
Attributes
Software Quality Models
Gurus
What is quality?
„
ISO 9000 – Quality management system
1994: The totality of characteristics of an entity that bear on its
ability to satisfy stated and implied needs.
2000: degree to which a set of inherent characteristics (i.e.
distinguishing feature) fulfils requirements (i.e. need or
expectation that is stated, generally implied or obligatory)
„
What do the gurus say?
„
1.
IEEE STD
1061:1993 (Software quality metrics methodology) - The degree
to which software possesses a desired combination of attributes.
610.12:1990 (Glossary of Software Engineering Terminology)
The degree to which a system, component, or process meets
specified requirements.
Philip B. Crosby I
„
„
„
Two dominant overall
views on software
quality:
Quality is a subjectively identified differently by
each individual and institution.
As this is not useful in software engineering
quality must be defined as “conformance to
requirements”
Nonconformance to requirements is the absence
of quality, quality problems become
nonconformance problems, and quality becomes
definable
2.
Conformance and degree
of satisfaction to an in
beforehand defined
specification.
The products or services
capability to meet
customer expectations –
explicitly stated or not
„
„
„
„
„
„
Joseph M. Juran
Walter A. Shewhart
Philip B. Crosby
W. Edwards Deming
Armand V. Feigenbaum
Kaoru Ishikawa
W. Edwards Deming II
Translating future needs of the user into
measurable characteristics
„ Constantly changing based on “real world”
- competitors, solutions, technology, price
„ Quality can be defined only in terms of the
agent.
„
1
Armand V. Feigenbaum II
„
Quality is based upon the customer’s actual
experience with the product or service,
measured against his or her requirements
stated
or unstated
conscious or merely sensed
technically operational
entirely subjective
always representing a moving target
Joseph M. Juran I
„
Quality can be:
Those
product features which meet the need of
customers and thereby provide product satisfaction.
Freedom from deficiencies.
„
„
Quality in terms of satisfying customer
expectations or specifications is not usable as it
is very hard to achieve.
Quality is fitness for use
Gurus vs. Models
„
Kaoru Ishikawa II
„
„
„
„
Quality defined according to standards (ISO,
IEEE etc.) contain shortcomings, does not reflect
constantly changing customer needs
Narrowly interpreted, quality means quality of
products.
Broadly interpreted, quality means quality of
product, service, information, processes, people,
systems etc. etc.
Quality must be defined comprehensively and
dynamically.
Walter A. Shewhart II
„
Quality from two perspectives:
An
objective reality independent of the
existence of the customer
The subjective perspective dependent on
individual thoughts, feelings or senses as a
result of the objective reality.
Software Quality Models
How well does the models actually meet
the definition of quality as described by the
gurus?
2
McCall’s Quality Model
McCall’s Quality Model
Boehm’s Quality Model
McCall vs. Boehm
FURPS(+) / Robert Grady
Dromey's Quality Model
„
„
„
„
„
„
Functionality – which may include feature sets, capabilities and security
Usability - which may include human factors, aesthetics, consistency in the
user interface, online and context-sensitive help, wizards and agents, user
documentation, and training materials
Reliability - which may include frequency and severity of failure,
recoverability, predictability, accuracy, and mean time between failure
(MTBF)
Performance - imposes conditions on functional requirements such as
speed, efficiency, availability, accuracy, throughput, response time,
recovery time, and resource usage
Supportability - which may include testability, extensibility, adaptability,
maintainability, compatibility, configurability, serviceability, installability,
localizability (internationalization)
+ - Design constraints, implementation requirements, interface requirements
and physical requirements.
3
ISO 9000:2000
„
ISO 9126
Quality management
principles:
ISO 9126: Software
Product Evaluation:
Quality
Characteristics and
Guidelines for their
Use
Customer focus
Leadership
Involvement of people
Process approach
System approach to
management
Continual improvement
Factual approach to
discussion making
Mutually beneficial
supplier relationships
ISO 9126
CMM
ISO 9126: Software
Product Evaluation:
Quality
Characteristics and
Guidelines for their
Use
CMM
P-CMM
Level
Focus
Level 5 – Optimizing
level
Continuous improvement
Level 4 – Managed
level
Product and process quality
Level 3 – Defined level
Engineering process
Level 2 – Repeatable
level
Project management
Level 1 – Initial level
Heroes
Key Process Area
Process Change Management
Technology Change Management
Defect Prevention
Software Quality Management
Quantitative Process Management
Organization Process Focus
Organization Process Definition
Peer Reviews
Training Program
Intergroup Coordination
Software Product Engineering
Integrated Software Management
Requirements Management
Software Project Planning
Software Project Tracking and Oversight
Software Subcontract Management
Software Quality Assurance
Software Configuration Management
No KPAs at this time
4
CMMI
CMMI
Excellence models
Quality - Gurus vs. Models
„
Common excellence models:
„
How well does the models actually meet the
definition of quality as described by the gurus?
„
From: According to specification.
To: Customer satisfaction.
Malcolm Baldrige National Quality Award
European Quality Award
Utmärkelsen Svensk Kvalitet
„
„
The excellence models contain criteria (within
leadership, process and technology) that enable
comparative evaluation of organizational performance.
Assessment criteria in excellence models provide a
basis for an organization to compare its performance
with the performance of other organizations.
„
„
„
Q = Deliverables / Expectations
Quality models focus on control of deliverables
5