1. Chapter 8 Software Quality Assurance

2. Software Quality Assurance
Software requirements
Specified standards – development criteria
Implicit requirements

3. Cost of Quality Prevention costs Appraisal costs Quality planning
Formal technical reviews
Test equipment
Training 
Appraisal costs
In-process and interprocess inspection
Equipment calibration and maintenance
Testing 

4. Internal failure costs
Failure mode analysis 
Repair
Rework
External failure costs
Complaint resolution
Product return and replacement
Help line support
Warranty work

5. Responsibility Project managers Software engineers SQA team
Salespeople
Customers

6. Quality Management & Software Development

7. SQA Activities
Prepares an SQA plan for a project to the software project team.
Participates in the development of the project’s software process description.
Reviews software engineering activities to verify compliance with the defined software process.
Audits designated software work products to verify compliance with those defined as part of the software process.
Ensures that deviations in software work and work products are documented and handled according to a documented procedure.
Records any noncompliance and reports to senior management.

8. Software Review

9. Why
To error is human
Large classes of errors escape the originator mare easily than they escape anyone else.
Defect amplification

10. Why SQA Activities Pay Off?
cost to find
and fix a defect
100
log
scale
10.00 10
3.00
1.50
1.00 1
0.75
Design
test
field
Req.
system
code
use
test

11. Defect Amplification
P.542 sommer

12. P.542 sommer

14. Formal Technical Reviews (FTR)
Objectives of FTR:
to uncover errors
to verify requirements
to ensure predefined standards
to achieve uniform manner
to make more manageable

15. The Players
review
leader
producer
reviewer
recorder

16. Conducting the Review 1. be prepared—evaluate
product before the review 2.
review the product, not
the producer 3.
keep your tone mild 4.
stick to the review schedule 5.
raise issues, don't resolve them 6.
record and report all review results

17. Review Summary Report What was reviewed? Who reviewed it?
What were the findings and conclusions?

18. Review Guidelines Review the product, not the producer.
Set an agenda and maintain it.
Limit debate and rebuttal.
Enunciate/specify problem areas, but don't attempt to solve every problem noted.
Take written notes.
Limit the number of participants and insist upon advance preparation.
Develop a checklist for each product that is likely to be reviewed.
Allocate resources and schedule time for FTRs.
Conduct meaningful training for all reviewers.
Review your early reviews.

19. Statistical SQA measurement • collect and categorize
information on all defects
Product
& Process
• find the causes of the defects
• using Pareto principle
• move to provide fixes
measurement
... an understanding of how
to improve quality ...

20. Example

21. Causes Incomplete or erroneous specification (IES)
Misinterpretation of customer communication (MCC)
Intentional deviation from specifications (IDS)
Violation of programming standards (VPS)
Error in data representation (EDR)
Inconsistent component interface (ICI)
Error in design logic (EDL)
Incomplete or erroneous testing (IET)
Inaccurate or incomplete documentation (IID)
Error in programming language translation of design (PLT)
Ambiguous or inconsistent human/computer interface (HCI)
Miscellaneous (MIS)

22. Phase & Error Index Phase Index
PIi = ws(Si/Ei) + wm(Mi/Ei) + wt(Ti/Ei)
Error Index
EI = (i x PIi) / PS
Ei = total number of errors uncovered during
the ith step
Si = the number of serious errors
Mi = the number of moderate errors
Ti = the number of minor errors
ws, wm, wt = weighting factors for serious,
moderate, and trivial errors
PS = size of the product

23. Software Reliability & Availability
MTBF = MTTF + MTTR
MTBF: Mean Time between failure
MTTF: Mean Time To Failure
MTTR: Mean Time To Repair
 Availability
Availability =[MTTF/(MTTF + MTTR)] x 100%

24. SQA plan 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
p.201

25. IEEE SQA Plan

26. The ISO 9000 Quality Standards
20 requirements:
management responsibility
quality system
contract review
design control
documents and data control
product identification …