Eight deadly defects in systems engineering and how to fix them
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Transcript of Eight deadly defects in systems engineering and how to fix them
Eight deadly defects insystems engineering and
how to fix themDr Joseph Kasser
Leverhulme Visiting ProfessorCranfield University
Agenda1. Selection of independent alternative solutions2. The V Model3. Lack of a standard process for planning a project4. The Waterfall model5. Unanswered and unasked questions6. Lack of a metric for the goodness of Requirements7. Focus on technological solutions not solving
customer’s problems8. The need to focus on people as well as process• Summary• Questions and discussion
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The selection ofindependent alternative
solutions• The systems engineering process has
identified three alternative candidatesolutions (A, B and C)
• “C” gets the highest score• Which one is the optimal?• Possibly none of them• Possibly a combination of the best parts of
all of them
The “V” Model
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Defects in the VModel
• Lacks ‘prevention of defects’• Definition of successful test?• Design works from requirements• T&E work from the need• T&E identify defects and plan to find them
after they have been built into the system• Why not prevent the defects?
* Kasser 1995
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The Project Cycle
DesignRequirement
Test
Acceptancecriteria
(property of a requirement)
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Prevention of defectiverequirements
• Requirements Workshopat UMUC and UniSA
• FRED and Tiger Pro• Figure of Merit for
document• Produced attitude
change in student’sperceptions
• Produced betterrequirements
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Lack of a standard processfor planning a project
Determination of objectives Determination of Resources
Generate preliminary work plan (risks)
Draft work plan version 1
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Lack of a standard processfor planning a project
Determination of objectives Determination of Resources
Identify and study lessons learned from previous projects
Negotiate objectives and resources
Generate preliminary work plan (risks)
Draft work plan version 1
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The Waterfall model• Waterfall approach does not cope well with
changing requirements.• Change the production process from the
waterfall approach to some type of rapid, spiral,or other methodology– Iterative waterfalls– Spiral focuses on Risk Management
• Result– Some improvement
• comparing Chaos 1995 with Chaos 2004
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Contract award
Vision of product
Intermediate milestones(product reviews)
Waterfall
Desired
Assumption behindWaterfall model
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Contract award
Vision of product
Intermediate milestones(product reviews)
Waterfall
Desired(moving target)
Real world ofchanges
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Contract award
Visions of product (converge)
Intermediate milestones(product reviews)Configuration Control(Stage Gates)
Cataracts
Desired (keep youreye on the balls)
Assumptions behindCataract model
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Unanswered andunasked questions
• Unanswered questions– Can you tell if the project is in trouble?– What percentage of the project is complete?
• Unasked questions at SRR– Are requirements with the following properties
really needed?• High cost, high risk• Low priority, high cost• Low priority, high risk
– Is this projected risk profile industry standard?
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Project Priority profiles(object-orientedrequirements)
Why are weinvesting inthis system?
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Project Risk profiles(object-orientedrequirements)
Risk: Is thisreasonable?
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Most successful IS ofthe 20th century?
• RAF Battle of BritainCommand, Control, &Communications System– No computers– Germany had better
Radar Technology– RAF evolved and used
an integrated system– Adequate technology
• System?• System of Systems?• Complex System?• Network enabled system?
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Not solvingcustomer's problems
• “the systems engineer is primarily interested in making equipmentchanges” [Goode and Machol, 1959] page 130).
• The problem the executive had was to secure at alltimes, live and accurate data concerning the exactconditions of the business. [Farnham, 1920] page 20)
• [Beer, 1972] page 244) describes a conceptual system.– British War Room in the Battle of Britain– NASA’s control room at the Manned Space Flight Center in Houston,
Texas.– bits and pieces of it existed at that time.
• Beer proposed a control centre• Today’s technology allows for personal desktop portals accessing
information via software agents in an integrated digital or networkcentric environment.
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Complex orcomplicated?
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The need to focus onpeople as well as process
• Literature– Is full of advice as to
how to make projectssucceed
– Has little if anything tosay about theproliferating processstandards
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The need to focus onpeople as well as process
• Systems engineering is a way of life– (Hitchins 1998)– Integration of
• Schedules• Design, Testing and Integration• Systems of Systems divide?
• Are we focusing on the right things?– The Standards do not provide metrics that can
predict the failure of a project.• (K&W, 1998)
Summary Selection of independent alternative solutions The V Model Lack of a standard process for planning a
project The Waterfall model Unanswered and unasked questions Lack of a metric for the goodness of
Requirements Focus on technological solutions not solving
customer’s problems The need to focus on people as well as
process
Questions?