CS3100Software Project Management

Week 26 - Quality

Dr Tracy Hall

Slide 2

Learning outcomes

1. To understand the wider implications of quality

2. To understand the options to monitor and control it

Slide 3

Triple Constraint . . again

Time

Budget

Concentrated here so far

Quality

What about this?

Slide 4

What is Quality?…the totality of features and characteristics of a product or service that bears on its ability to satisfy stated or implied needs.

American Society of Quality

Degree to which a set of inherent characteristic fulfills requirements

ISO 9000

Fitness for purpose

Perceived Quality - Reputation

Slide 5

A wider view of qualityTime

BudgetQuality

Checks &feedback Inter-

operability

Ease of useError-free use

Clear interface

ImpactLiability

Standards

Profits

Maintenance

CompatibilityUpgrades

Reputation

Marketing No bugs

Well-codedGood design

interfaces

functions

features

reliability

speed

latency

Slide 6

Different perspectives

PEOPLE End User

Customer

Managing Director

Legal Team

Developer

What is quality from these

perspectives

Slide 7

Cost of prevention

amount spent to ensure work will be done correctly

includes risk reduction and error prevention

e.g. getting design right before production

activities may include supplier evaluation, training and staff development

Quality planning; formal technical reviews; test equipment; training

Cost

Defects

Time

What is the cost of quality?

Am

ount

Slide 8

appraisal costs association with

inspection and testing - company’s products- supplier’s products

e.g. testing, walkthroughs, design reviews

In-process and interprocess inspection; equipment calibration and maintenance; testing Cost

Defects

Time

Other costs associated with quality

Slide 9

internal failure cost of putting everything right while project still under

control (pre-delivery) re-coding software for problems found at internal

testing Rework; repair; failure mode analysis

external failure costs incurred post-delivery

- warranty/support costs- maintenance- handling complaints

lost future business Complaint resolution; product return and replacement;

help line support; warranty work

The killers

Slide 10

- A total of 7053 hours was spent inspecting 200,000 lines of code with the result that 3112 potential defects were prevented.

- Assuming a programmer cost of $40.00 per hour, the total cost of preventing 3112 defects was $282,120, or roughly $91.00 per defect.

- No inspections but that programmers had been extra careful and only one defect per 1000 lines of code escaped into the shipped product. That would mean that 200 defects would still have to be fixed in the field.

- At an estimated cost of $25,000 per field fix, the cost would be $5 million, or approximately 18 times more expensive than the total cost of the defect prevention effort

Internal failure

External failure

(Pressman 1997, p192)

Costs of avoiding poor quality

Slide 11

Attributes

portability

completeness

security

efficiency

reliability

speedmaintainability

usability

conciseness

Slide 12

How do we ensure quality?

Is it about measurement and process?

Can you measure quality?

Do you just check for quality at the end?

Slide 13

Prioritising problems

80:20 Rule

80% problems stem from 20% sources

Focus on the 20% first

But don’t neglect the other 80%

Slide 14

V Model

Quality Control throughout Software LifeCycle

unit test

integration test

systems test

acceptance testfeasibility

analysis

design

program specs

coding

Inspection stream

Testing stream

Slide 15

Other Processes

ISO 9000

CMM Software Engineering Institute

Motorola

TQM

Six Sigma

Look up some of these terms on the internet, academic papers etc.

Slide 16

ISO 9000

International Standard

Focusess

Documentation of Process

Documentation of Proof of Process

Requires Certification

Re-Certification

Slide 17

corporatequalitymanual

critical proceduresmanual

- corporate- divisional- functional

procedureguides documentation detailed work

instructions

policyobjectivesorganisationprimary functionsprocedures index

who does:whatwhenhowin what sequence

Quality management system structure (Cadle & Yeates p240)

Structure

Slide 18

planning a formal definition of how it will work

provides key reference point for project team members

acts as a bridge between customer and the supplier

provides a discipline and offers a framework against which issues can be considered and addressed before and during a project.

Quality Plans

Slide 19

CMM Capability Maturity Model

Level 1 - InitialUnpredictable and Poorly controlled

Level 2 - RepeatableAble to repeat previously mastered tasks

Level 3 - DefinedProcess is understood

Level 4 - ManagedProcess is measured and Controlled

Level 5 - OptimizingFocus on process improvement

Slide 20

TQM Total Quality Management

Total = Whole organisation

Encourage culture of achieving and

maintainting quality

Slide 21

Quality in 30 seconds

Understand it Recognise the Causes Positive Negative

Plan it: Work out how to measure it Work out how to make it happen Make it easy for your team to exhibit quality

Implement it, and……encourage a Culture for Quality