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The Importance of the Requirements Phase. Shuly Cooper. To Be Discussed. Product Quality – Definition The issues and their root cause Cost of Quality (or lack of it) A Tool – Quality Function Deployment (QFD) Briefly – More quality tools ► Inspections - PowerPoint PPT Presentation
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04/20/23 1
The Importance of the Requirements Phase
Shuly Cooper
04/20/23 2
• Product Quality – Definition• The issues and their root cause• Cost of Quality (or lack of it)• A Tool –
– Quality Function Deployment (QFD) • Briefly –
– More quality tools ► Inspections
► Iterative/incremental dev. (small deliverables) – The deliverables of the Requirements Phase
To Be Discussed
04/20/23 304/20/23 3
19451980s
“Higher Accuracy & Reliability”
The Era of Statistical Process Control (SPC)
Dr. W. Edward Deming
Dr. Peter F. Drucker
Product Quality - Definition
Act Plan
Check Do
The Deming Cycle:
04/20/23 4
Studies by the Standish Group
• 2001 data• 44% of software projects finish on time• 56% of projects completed at –
– 222% of the duration originally planned– 189% of the original budgeted cost– 70% of projects reduced their planned scope
significantly– 30% were cancelled before completion
• Ref: http://www.pqa.net/ProdServices/ccpm/W05002001.html
The Challenges (1 of 2)
04/20/23 5
Capers Jones, Software Productivity Research LLC
• 1995 - 2004 data
• An analysis of ~250 large software projects • Size > 10,000 function points (~ 1,250,000 statements in
C)• Success vs. failure were analyzed at opposite ends of the
spectrum– ~ 25 (10%) projects were successful– ~ 50 (20%) projects had delays or overruns below 35% – ~ 175 (70%) projects experienced major delays, budget
overruns, reduced scope, or were terminated
The Challenges (2 of 2)
04/20/23 6
• Poor requirements 27%• Unanticipated technical difficulties 25%• Training 20%• Poor Project Management 17%• Lack of management support 6%• Other 5%
Source: John Carter - Product Development Consulting, Inc - Spin 1997 -
Root Cause for Development Schedule Slip
04/20/23 7
Engineers’ Awareness at the Start of a Project
• Priority Decision Criteria 20% 36%• Product Positioning 22% 41%• Strategic Alignment 18% 41 %• Organization Support 20% 43%• Risk Assessment 26% 44%• Competitive Analysis 21% 47%• Understanding User Needs 21% 48%• Regulation Compliance 60% 73%
Others Best
Source: John Carter - Product Development Consulting, Inc Berkeley Software Forum - 1996
The Current State of the Requirements Phase
04/20/23 8
Capers Jones
• The two most common causes of software project failures are :– Risk analysis– Vague a/o changing customer’s requirements
• Ref: http://www.isixsigma.com/library/content/c010618b.asp
04/20/23 10
The Cost of Fixes
Resources’ bleeding
04/20/23 11
Cost of QualityIBM -- late 70’s
100K
10K
1K
100
10
0
Log (Cost to Find&Fixper Defect) ($)
Reqs. Design Coding Sys.Test Release
Phase
04/20/23 12
Cost to Fix a DefectSemantech -- 90’s
Requirements $195
Design $489
Coding $997
System Testing $7,136
Deployment Much more
SEMATECH Technology Transfer #92111389A-TRG, March 5, 1993
Source: Chuck Hoffman - Virtual Consulting Inc. - Spin 2001
04/20/23 1304/20/23 13
Log [Cost of NOT Finding & Fixing a req. defect($/Defect)
Cost of Quality
100K
10K
1K
100
10
0
Log [Cost to Find&Fixper Defect] ($)
Reqs. Design Code Sys.Test Release
Phase Found
=> The most expensive faults are seeded during the Requirements Phase.
When faults migrate from phase to phase, they multiply 10-12 times
A Quality Gates
IBM
04/20/23 15
Defects Classified by Time of Introduction (1970s)
Jones* Thayer** Boehm*** Bell Labs
Requirements 10% 8-10% 15%
Functional Design 15% 55% 15-20%
Logical Design 20% 25-35%
Coding 30% 35% 25% 35%
Documentation, etc. 35% 17-20%
* “Measuring Programming Quality and Productivity,” Jones, IBM Systems Journal, 1978
** Software Reliability: A Study of Large Project Reality, Thayer, Lipow & Nelson, North-Holland, 1978
*** “Developing Small Scale Application Software Projects: Some Experimental Results,” Boehm, Proceedings, IFIP 8th World Computer Congress,1980
Source: Chuck Hoffman - Spin 2001
45%45%
04/20/23 16
Hewlett Packard’s Experience (1990s)
28%
30%
7%
35%
Specification
DesignCoding
Other
Source: “Implementing and Sustaining a Software Inspection Program in an R&D Environment,” MacLeod, Hewlett-Packard Journal, June 1993
Source: Chuck Hoffman - Spin 2001
04/20/23 17
Distribution of Effort to Fix Defects
Code7% Other
10%Design
27%
Requirements56%
Code1%
Other4%
Design13%Requirements
82%
Why Manage Requirements (2000)
Distribution of Defects
Source: Larry Boldt - Technology Builders, Inc. - Spin 2001
04/20/23 18
Log Cost to Find & Fixper Defect ($)
Find & Fix Defects as Early as Possible
100K
10K
1K
100
10
0Req. Design Code Sys. Test Release
Phase
10%
20%
30%
40%
50%
% of DefectsIntroduced
Quality Gates
O
O
O
O
04/20/23 20
A New Definition of Quality
04/20/23 21
1980
Exceeding Customer expectations
Prof. Yoji Akao -- U. of Tokyo
Deals with the total customer experience
Part of “Hoshin Kanri” (Japan)
Ref – http://www.qfdi.org/
Product Quality – Definition
04/20/23 2204/20/23 22
QFD Maps “What” to “How”
WHAT
HOWMRKT.
DEV.
HMLH
M
L
1234
5
6
A B C D E
H
H
H
HM
M
M
M
L
L
L
L
H
H
TOTAL
COMPETITOR
TOTAL
IMPORTANCE F
L=1M=3H=5
NEEDS
FEATURES
04/20/23 2304/20/23 23
QFD for this Lecture
MRKT.
DEV.
HHMM
M
MH
HH
H
HL
L
M
H
L
TOTAL
COMPETITOR
TOTAL
IMPORTANCE
Clear/EasyCorrect (no errors)
Promote QA/Req.
Low cost
Long shelf life
Research
Provide D
ata
Colors
Sections
Font size
Exam
ples
Fun/Aesthetic
H H
L=1, “Bells & Whistles”M=3H=7, “A Show Stopper”
91
39
110 66 66 42 39 30 353
M
M
M M
L L
91108 0
24M
HOW
WHAT
04/20/23 24
A Sample of Customers’ Needs (QFD – first column) (1 of 2)
• Feature set/Capabilities• Reliability (MTBF)• Safety/Security• Recoverability (zero loss of data)• Scalability (different platforms, apps., tunable,
modular)
04/20/23 25
A Sample of Customers’ Needs (QFD – first column) (2 of 2)
• Performance (higher speed)• Usability (easy to set-up, use, maintain)• Friendliness (easy to learn)• Supportability (service, 24x365)• Release date/Availability • Aesthetics
04/20/23 26
QFD – Benefits – (1 of 2)
A TEAM communication tool
• A “semi-mathematical” tool• Drives consensus across organizational
boundaries• Prevents “politics”, “lobbing” and “power struggle”• Stabilizes requirements
04/20/23 27
QFD – Benefits – (2 of 2)
• Helps organizations to focus on customers’
satisfaction Maps customers’ needs into high level features
• Cost saving –“Gets it right the first time” • Reduces risk Identifies competitive features
and strategies
04/20/23 28
QFD – Cost
• Planning• Depends on project size, 4-10 marketing and
development engineers (all groups involved)• About 1 hr/10X10 matrix• Analyzing, storing, and reporting results
04/20/23 29
Companies that are using QFD
IBM MitsubishiDigital ToyotaAT&T FordHP GMSony Daimler ChryslerGE BoeingRaytheon Lockheed Martin
Sybase - ClusteringMicro Focus - Year 2000 Solution
04/20/23 30
Entry Criteria for the Requirements Phase
There is – • A vision and an idea• A sponsor for the first phase of the project
04/20/23 31
Requirements Phase Deliverables
• Market Requirements Document• Product Specifications • High Level Project Plan• Management support for the next phase
• Process Documents and Infrastructure• Maintenance Documents and Infrastructure• Black Box and Acceptance Test Plans
• Initial contracts with potential customers and vendors
04/20/23 32
Exit Criteria for the Requirements Phase
All documents – • Are written, inspected and approved by all
stakeholders • All related issues/risks are resolved or managed• Objectives are measurable, optimized, prioritized
and approved
04/20/23 3304/20/23 33
Quality Gates – following the Requirements/Design Phases
Documents’ Inspections/Peer Reviews
• 1976 – Introduced by M. E. Fagan - IBM• A formal process• Bell Labs experience:
– Cost of inspecting all deliverables 5-20% of project development cost*– ROI of inspecting all deliverables 200-1200%*
* Bell Labs data
04/20/23 3404/20/23 34
HP – Inspection Data
Grady, R. B. and Van Slack, T., “Key Lessons in Achieving Widespread Inspection Use”, IEEE Software, V. 11, N. 4, Month, 1994, pp. 46-57
Phase Est. Starting Point
Est. Adoption 1993
% Cost Saved
% Rework
Est. $ Savings Per Year
Spec. 1% 29.5% 28.5% 17% $10,175,000
Design 1% 34.8% 33.8% 11% $7,808,000
Code 5% 42.3% 37.3% 4% $3,133,000
Test Plan 1% 17.1% 16.1% 1% $338,000
TOTAL 33% $21,454,000
04/20/23 36
The Incremental Model – Web
Requirements H.L.Design
L.L.Design
Coding
TestingTesting
Integration
Sys.Test
Delivery
L.L.Design
Coding
TestingTesting
Integration
Sys.Test
Delivery
L.L.Design
Coding
TestingTesting
Integration
Sys.Test
Delivery
04/20/23 37
The Incremental Model – Med. Device
Requirements H.L.Design
L.L.Design
Coding
TestingTesting
Integration
Sub-Sys.Test
L.L.Design
Coding
TestingTesting
Integration
Sub-Sys.Test
L.L.Design
Coding
TestingTesting
Integration
Sub-Sys.Test
Integration+Test
A “big-bang” delivery Delivery
04/20/23 38
The Iterative Model – Web Reqs+Arch Reqs+Arch. Reqs+Arch.
Design
Coding
TestingTesting
Integration
Sys.Test
Delivery
Design
Coding
TestingTesting
Integration
Sys.Test
Delivery
Design
Coding
TestingTesting
Integration
Sys.Test
Delivery
04/20/23 39
• It is a strategic phase• If this phase is not performed well the project has a
higher probability for failure• Invest about 15-20% of resources • Many organizations skip the phase or implement it
poorly• More than 15-20% change in requirements means a
new project and a new round of planning (!)
The Requirements Phase– Lessons Learnt