Cocomo Lecture II EEE493 2000

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Cocomo - Lecture II EEE493 2000
Royal Military College of Canada Electrical and
Computer Engineering

• Major Greg Phillips
• greg.phillips_at_rmc.ca
• 1-613-541-6000 ext. 6190

Dr. Scott Knight knight-s_at_rmc.ca 1-613-541-6000
ext. 6190
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Refs

• Pressman, R.S., Software Engineering a
  Practitioners Approach 5th Ed., McGraw-Hill,
  2001, Chapter 4
• Boehm, Barry, Software Engineering Economics,
  Prentice-Hall, 1981

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Teaching Points

• Modes of development
• Intermediate COCOMO model
• Example

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Review

• What is the major cost driver in COCOMO?
• What economies of scale does COCOMO seem to
  capture? How do we see this in the model?
• What diseconomies of scale does COCOMO seem to
  capture? How do we see this in the model?
• What are phase distributions used for?

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Consider

• All software is not developed under the same set
  of circumstances
• What about developing
• new kinds of systems
• in new development environments
• on hardware being developed at the same time
• using new algorithms
• in an embedded environment
• under contract
• Introduce 3 Modes of Development

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Organic Mode

• As in previous discussions, small-to-medium sized
  product development in a familiar, in-house
  development environment. A generally stable
  development environment, minimal need for
  innovative data processing architectures and
  algorithms. Relaxed schedule constraints.

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Semidetached Mode

• Team members have an intermediate level of
  experience with related systems. Perhaps a
  mixture of experienced and inexperienced people.
  Parts of the project may require rigorous
  interfaces.

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Embedded Mode

• Need to operate within tight constraints.
  Product must operate within a strongly coupled
  complex of H/W, S/W, regulations, and operational
  procedures. Cost of changing other parts of the
  complex is high. Tighter requirements and more
  inflexible scheduling.

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Basic COCOMO Formula
Note what is happening to the scalars and
exponents
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Example Estimates
Note large changes in effort and
productivity, small changes in schedule
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Phase Distributions
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How good is it?

• This is an empirical model so it can only be as
  good as its database
• For the data it was calibrated toBasic COCOMO
  is
• within a factor of 1.3 - 29 of the time
• within a factor of 2 - 60 of the time

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Basic COCOMO Accuracy
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Intermediate COCOMO

• Basic COCOMO plus
• the addition of 15 more cost driver attributes
• new set of effort equations
• Accuracy
• within a factor of 20 - 68 of the time

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Intermediate COCOMO Accuracy
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Intermediate COCOMO Formula
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Cost Driver Effort Multipliers
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Cost Driver Ratings
Note see handout for module complexity ratings
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A Pricing ExampleMicroprocessor Communications
Software
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Cost Driver Ratings Microprocessor
Communications Software
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Project Cost Microprocessor Communications
Software

• PMnom 2.8(10)1.2 44 pm
• PMadj 44 pm ? 1.17 51 pm
• 51 pm ? 6000 /pm 306,000

nominal
adjusted
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