Estimating Software Projects

1
Estimating Software ProjectsActivity
Scheduling in the Dynamic, Multi-Project Setting
Choosing Heuristics Through Deterministic
Simulation
2
Acknowledgements

• Estimating Software Project
• R. Agarwal, Manish Kumar, Yogesh, S. Mallick,
  R.M. Bharadwaj, D. Anantwar
• Activity Scheduling in the Dynamic, Multi-Project
  Setting Choosing Heuristics Through
  Deterministic Simulation
• Robert C. Ash, Division of Business and Economics
• Indiana University Southeast

3
Introduction

• What?
• Why?
• How?

4
Approaches for Defining Software Volume

• Parametric
• Heuristic

5
Parametric Approaches

• COCOMO
• COCOMOII
• COCOTS
• Function Points
• Newer Approaches Object metrics Graphical User
  Interfaces (GUI) metrics

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COCOMO (COnstructive COst MOdel)

• Most fundamental calculation
• (PM)
• A proportionality constant
• B depends on development mode
• SIZE SLOC, KLOC
• PM Person-Months

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COCOMO - MODELS

• Basic Model
• Intermediate Model
• Detailed Model
• Time to develop (TDEV) (months)

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Example Project of 3k LOC(Organic Mode)

• Basic Model
• Effort 2.4 31.05 7.6 PM
• TDEV 2.5 7.6.38 5.4 Months
• Avg. staffing 7.6/5.4 1.4 person(s)
• Intermediate Model
• EAF 1.30 1.10 1.43
• Effort EAF 3.2 (3k)1.05 14.5 PM
• TDEV 2.5 14.5.38 6.9 Months
• Avg. staffing 14.5/6.9 2.1 person(s)

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COCOMO II

• Advanced version of COCOMO.
• Two Models developed to be used for two stages of
  software development
• Early Design Model
• Post-Architecture Model

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Stages/Equations

• Basic Equation

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COCOTS(COnstructive COTS)

• COTS Component assessment
• Tailoring
• Development and Testing of glue code
• Increase level programming due to volatility

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Function Point Analysis

• Developed to overcome difficulties associated
  with LOC as a measure for predicting effort.
• Measures from functional perspective independent
  of technology.
• Track and monitor scope creep.
• FP Counts can be compared at end of phases.

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Major Components

• External Inputs (EI)
• External Outputs (EO)
• External Inquiry (EQ)
• Internal Logical Files (ILFs)
• External Logical File (EIFs)

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Function Point Count

• FP UAF x VAF

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Benefits of Function Point Analysis

• Used to size software applications more
  accurately.
• Different people can use them to obtain the same
  measure.
• Easily understood by the non-technical user.

16
Heuristic Approaches

• Bottom Up
• Top Down
• Expert Judgment Wideband Delphi
• Estimation by Analogy
• Deterministic Simulation

17
Deterministic Simulation

• Overcome shortcomings found in other project
  scheduling tools.
• Assume unlimited personnel and resources.
• Applied to one project at a time.
• Effective tool for choosing the heuristics that
  best fits the projects and activities.

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Pre-conditions for Deterministic Simulation

• Database for critical project resource pools.
• Activity information for known projects loaded in
  project software program.
• Algorithm loaded in project software program.

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Example
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Conclusion

• Which cost estimation model?
• How to measure software size in LOC or FPs?
• What constitutes a good estimate?