Transcript Requirements: Elicitation - Lyle School of Engineering

EMIS 8390
Systems Engineering Tool—applying tools to
engineering systems
Requirements:
Elicitation
UPDATED 12/02/04
Mark E. Sampson
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Requirements Elicitation
• Standish Group claims “lack of user input” is one of the
main contributors to runaway projects.
• Some quotes:
“15%
of projects fail outright, 51% are challenged” Standish
“53%
of projects will cost 189% of estimates” Standish
“only
67% of originally defined features show up in the finished
product, of those 45% are NEVER used” Standish
“half
of resources spent on product development are spent on
products that fail” 2003 Harvard Business School Cyberposium
“90%
of electronics components function as designed, 50% of
them fail when integrated with their systems” IEEE Design Magazine
…the process of discovering the requirements for a system
by communication with customers, users, and other
[Sommerville, 1997] 2
stakeholders.
Requirements Elicitation Problems…”Yes, but”
• “Yes, but…”
…that’s so cool, but it would be nice if it…
•
•
•
•
Caused by human nature
Anticipate some “buts…”
Do them early in the process with prototypes
Tend to be at the interfaces/touch points
[Leffingwell, 2000]
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Requirements Elicitation Problems…”Gold Miner”
• “When are you rich enough”
…let’s do another pass by…
…there’s a few more avenues we haven’t checked…
• Systems Engineering nature
• Scope statement boundaries the problem and
establishes your objectives (how you know when you’ve
arrived). When the extracted requirements adequately
address your objectives…your there.
[Leffingwell, 2000]
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Requirements Elicitation Problems…”bring me a rock”
• Users don’t know what they want
• Prototyping
• Stick with it until you get some definition
• Watch them in action (beware the Hawthorne effect)
[Leffingwell, 2000]
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Requirements Elicitation Techniques…Reuse
• Find if it’s already been done and reuse it.
• Saves money & time
• Reduces risk
• How?
• TRIZ uses inventive patterns (see class 1)
• Analogs…Nature (already worked out the kinks)
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Analog: Anatomy of a project...
Nervous System
(SE & SE Tools--connects
management to project)
Epidermal System
(facilities, security)
Digestive System
(Personnel, finance
provides energy/resources
for project)
Skeletal System
(project support groups)
Brain
(Project Management)
Muscular System
(Does the work…
engineering, etc.)
Circulatory System
(Information Systems,
LAN’s, PDM)
Respiratory System
(Marketing bringing in
new ideas)
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Requirements Elicitation Techniques…Interviews
• Find a user/customer and ask them.
• Proves there is a need.
• Boundaries the market
• Live communication, builds relationship with market
• How?
• Unbiased questions…”who is the user”?
• Ask Why? Solutions Selling.
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Requirements Elicitation Techniques…Brainstorming
• Find a user/customer and brainstorm around a problem
(see class 1).
• Idea generation and reduction
• Combine ideas
• Voting schemes
• How?
• Live, using stickee note
• Web-based brainstorming
• A variety of techniques supported by tools--Delphi,
mindmaps,…both installed and web-based
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Requirements Elicitation Techniques…Surveys
• Find a potential user and get them to answer some survey
questions.
• more efficient to cover a wide swath of potential users
• Statistically measurable/confidence
• How?
• Paper
• Web-based Surveys—TcCommunity, grapevine,
formsite, web-online-surveys,…
• How to write questions to get to the information you
need? http://www.statpac.com/surveys/
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Requirements Elicitation Techniques…Use Cases
• User interaction model
• Identify who, what & how of product behavior
• Describe the interaction between user and system—
what the system does for the user
• Describe functional behavior
• How?
• Modeling environments
that support UML
• Drawing/diagramming
tools (Visio, PPT)
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Requirements Elicitation
Techniques…Regulations/Standards
• Describe what the product must comply with…
…another source of requirements
…constraints/drivers point out things you can do nothing
about…
Where do you get them
from?
Introduction/demonstration
With George Bell/Steve Haas
Information Handling Services
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Requirements Elicitation Techniques…Scenario
Generators
• Virtual environments describing aspects that impact our
system
• Weather/environment
• Economic/Financial (ALM, ESG,…)
• Missions (TAC Brawler), Electronics (EWSG)
…produces an event
chain/time line that can
drive out requirements
(…must deal with 3
targets at the same time)
TCT Kill Chain
Engaged by a Joint Battle Force
J-STARS
w ATR
U-2
UA
V
DCGS
CAOC
TADI XXX
ARMY Tactical
L
Operations Center
NET
BCC
XX
USMC XX
TAOC
AEGIS
XX
AIR DEFENSE
TOC
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Requirements Elicitation Techniques…Data Mining
• Similar to reuse, except it relies on prior data to drive out
requirements. The problem is finding the needle in the
haystack…
…for example: Beer and Diaper Sales spike ~8:00pm
• start with existing data and look for anomalies/patterns
Tools…Probe, KD1,
Matlab, PVWave,…
Data Analysis Introduction &
Demonstration with
Matlab/Simulink
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Requirements Elicitation Techniques…other
• Role playing
• Storyboarding
• Prototyping
• JAD (Joint Application Development)
• Delphi
• Gaming
•…
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