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1qual-i-ty 'kwa^:l-et-e^- pl -ties [ME qualite, fr. OF
qualite', fr. L qualitat-,
qualitas, fr. qualis of what kind ] 2a: degree of excellence:
GRADE 2b: superiority in kind
«Quality is the relationship between what I expected and what I got.»
«[Q]uality has much in common with sex. Everyone is for it. (Under certain conditions, of course.) Everyone feels they understand it. (Even though they wouldn't want to explain it.) Everyone thinks it is only a matter of following natural inclinations. (After all, we do get along somehow.) And, of course, most people feel that problems in these areas are caused by other people. (If only they would take the time to do things right.)»
- P. Crosby, Quality is Free, 1979
Reexamine preceding quote:
«Quality is the relationship between what I expected and what I got.»
That is, how can I assure that I get what I expect.
What QA is there for:
* slot machine
* cooking
* manufactured item
* software
External Factors
* competitive pressure
* product evaluation commonplace
* poor quality destroys an organization's reputation
* customer demand
* regulatory requirement
Internal Factors
* fixing a problem after completion of a project is 100 times more expensive than catching the problem during specification and design
* for every dollar spent for development of software, two dollars are spend on maintenance
Professionalism
* professional obligation to produce quality software
defect found at impact
origin step very minor
next step minor delay
end of line rework
rescheduled work
final inspection significant rework
delay in delivery
additional inspection
end user's hand liabilities
warranty cost
administrative cost
damage to reputation
loss of market share
Gain control:
Increase capability:
MTTF = mean time to failure
MTTR = mean time to repair
Availability = MTTF / (MTTF + MTTR)
* applied to manufacturing in the early 20th Century through production monitoring.
* used statistical methodologies to predict undiagnosed failure rates and locate defect «hot spots.»
Steps in assuring quality of a toaster:
1. test toaster at the end of the assembly line
Vmany throw-aways or re-works
V2. test toaster components during assembly
Vassembly line bottle-necks at some failure-prone step
V3. monitor & measure assembly process itself
hence QA plan is mostly concerned with process, not product
Traditional QA relies on:
Technical Interpersonal Measurement Objectives Monitoring Evaluation Feedback Empowerment
Management Support
* Deming Prize
* Baldrige Award
+ QS 9000 (US auto industry)
+ ISO 9000
* Military standards
o Meets specifications
- No quality system
4.1 Management Responsibility
4.2 Quality System
4.3 Contract Review
4.4 Design Control
4.5 Document & Data Control
4.6 Purchasing
4.7 Customer Supplied Components
4.8 Product Identification & Traceability
4.9 Process Control
4.10 Inspection & Testing
4.11 Control of Test Equipment
4.12 Inspection & Test Status
4.13 Control of Non-conforming Product
4.14 Corrective & Preventive Action
4.15 Handling, Packaging, etc.
4.16 Control of Quality Records
4.17 Internal Quality Audits
4.18 Training
4.19 Servicing
4.20 Statistical Techniques
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manufactured
products software
internal variability
variability in external
environment
continuous behavior discrete
basically additive highly non-linear
scalability issue
manufacturability complexity
issue issue
«[S]oftware quality is the whole issue of software engineering.»
- A. Macro, 1990
«[Software quality is] conformance to explicitly stated functional and performance requirements, explicitly documented development standards, and implicit characteristics that are expected of all professionally developed software.»
- Pressman, 1987
Process
* methods and tools
* configuration management and change control
* standards and standard compliance mechanisms
* reporting mechanisms
Verification and Validation
* formal technical reviews
* multi-tiered testing strategy
* measurement
o symbolic execution
=> formal verification techniques
- after McCall, 1977
- Weiss & Basili, 1985
«Software Science»
* begins with count of operations and distinct operands, combined using various formulas
* has both strong proponents and strong detractors
Cyclomatic Complexity
* counts number of simple cycles in flow graph
* applies at design stage
* relates to testing complexity
Higher-Order Measures
* length * f(data flow)
Specification
focus on parts meet any inspection
product specifications system
ISO 9000
focus on process QS 9000
process under control
Capability Maturity Model
focus on organization SEI
culture under control certification
«Levels of Maturity»
1. Initial
V disciplined process
2. Repeatable
V standard, consistent process
3. Defined
V predictable process
4. Managed
V continuously improving process
5. Optimizing
Outline of IEEE Standard for Quality Assurance Plans (STD 730-1984)
1. Purpose and Scope
2. References
3. Organization, Tasks, and Responsibilities *
4. Documentation Required
5. Standards, Practices, and Conventions *
6. Reviews and Audits *
7. Configuration Management *
8. Problem Reporting and Corrective Action *
9. Tools, Techniques, and Methodologies
10. Code Control *
11. Media Control
12. Supplier Control *
13. Records Collection, Maintenance, and Retention
* important
* not applicable to InfoSys
Management will require QA
Management will specify overall QA plan
Management will indicates what variations are
* allowed
* required
© Copyright Edward Robertson, 2108-10-20