Planning Iterative Software Development Projects

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Planning Iterative Software Development Projects

• Raj Agrawal, PMP
• Unisys

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Synopsis

• Iterative software development projects require a
  different approach to project planning as
  compared to traditional waterfall projects. This
  is especially true in areas such as estimation of
  effort, technical risk mitigation, schedule
  development, resource planning scope
  management. Experiences, lessons learned and
  best practices derived in parametric estimation,
  iterative development of schedules, requirements
  development analysis will be discussed.

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Overview

• Introduction
• What is iterative development?
• Reality Requirements Change!
• Why iterative development?
• Challenges of iterative development
• Estimation
• Estimation techniques
• Top down or bottom-up estimation?
• Planning
• Project Plan development
• Resource Plan development
• Scope management iteration by iteration
• Conclusion

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What is Iterative Development?

• Development methodology to improve software
  project delivery
• Divides project into mini waterfall projects
  called iterations
• Requirements per iteration are based on technical
  risk mitigation and business value
• Iteration duration is typically 4-12 weeks
• Iterations are timeboxed fix end date and
  remove requirements if slippage
• Each iteration delivers a partial working system
• Requires continuous negotiation between scope,
  solution project plan

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Reality Requirements Change!
Source How to Fail with the Rational Unified
Process Seven Steps to Pain and Suffering,
Craig Larman, Philippe Kruchten, Kurt Bittner
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Why Iterative Development?

• Mitigates risk
• Assumes requirements will change over project
  life
• A tested partial solution enables feedback to
  align requirements and design
• Provides early indication of project progress
• Provides basis for early scope negotiations
  management
• Reduces Gold-plating Requirements Creep

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Challenges of Iterative Development

• Cost estimation without a detailed WBS
• Rolling Window Planning - Project Plan only
  detailed to next iteration
• Requirements analysis during each iteration may
  lead to changes to baseline
• Clients need to prioritize requirements
• Architects need to identify and prioritize
  technical risks
• Waterfall milestones such as SDR, PDR, CDR need
  to be mapped

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Estimation Techniques

• Top down estimation requires
• A cost estimation tool
• Measure of volume
• Input for languages
• Environment parameters
• Bottom up estimation requires
• A detailed WBS
• Estimates for each lowest element of WBS

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Top Down or Bottom Up Estimation?

• They complement each other
• Use top down estimation for application
  development
• Bottom up estimation
• Validation of top down estimate
• Estimate each iteration and discipline within
  iteration
• Add other items such as business modeling
  system integration

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Project Plan Development

• Create high level plan based on estimate
• Phase dates
• Iteration plan
• Iteration dates
• Key milestones
• Detail the first phase first iteration
• Develop next iteration plan mid-way through this
  iteration

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Resource Plan Development

• Use hours estimate from the cost model
• Use hours by roles from cost model
• Spread hours over the timeline
• Assign staff to roles

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Scope Management Iteration by Iteration

• Each iteration is time-boxed
• Requirements dropped from an iteration move into
  next iteration
• Only if requirements are prioritized
• Architecture is defined
• Technical risks are prioritized
• Close stakeholder involvement is needed for scope
  management

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Conclusion

• Iterative development requires a different
  mindset do the hard work first
• Stakeholders need to involved closely
• Estimation tools aid planning
• Requirements should be prioritized
• Architecture centric design
• Iteration plan should mitigate risks
• Leads to adaptive development