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The Capacity Constraint

Learn how to prioritize features, determine release timelines, and allocate resources based on the capacity constraint. Avoid common pitfalls and manage organizational issues effectively.

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The Capacity Constraint

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  1. The Capacity Constraint Lecture 4

  2. Release Planning • What to Build: • have a big list, choose the most important from it • By when to build it: • not too early that we flood our customers with releases and the overhead kills us • not too late that they think us unresponsive • Using how many people • usually fairly fixed for the next release. • For the next release, determine • What to build, • By when to build it, • Using how many people. Can we do all three? Lecture 4

  3. A geometric analogy p e r s o n s days 1 person-day The Capacity Constraint • A fundamental constraint that governs all planning activity. Lecture 4

  4. Features The Capacity Constraint • A fundamental constraint that governs all planning activity. A geometric analogy People Days A certain requirement A certain capacity Lecture 4

  5. features people days The Capacity Constraint • A fundamental constraint governs all planning activity. It’s ‘gotta all fit! Lecture 4

  6. Release Planning • What to build F • By when to build it T F  N x T • Using how many people N • Need to build an initial plan that respects the capacity constraint • Need to continuously update the plan to maintain its adherence to the capacity constraint. Lecture 4

  7. Most Common Problem • Comes from either • not knowing • knowing but hoping for the best (Yourdon Death March) (can happen initially or as we go) Lecture 4

  8. Add time Cut features Both Dealing with Issues as they Arise Developer leaves the team Lecture 4

  9. Other Happenings Lecture 4

  10. Organizational Issues • Management must appreciate that software development carries with it certain inherent risks. • The business of a software organization is to manage and adapt as possibilities continuously become reality. • Ranting and raving is unproductive • With good data, good managers will make good decisions. Lecture 4

  11. F = N x T N T The Quantitative Capacity Constraint • Post-Facto, the following relationship must hold. • But, it requires careful definition. We define carefully so that we know what it is we are trying to estimate, and how to compare actuals against estimates for post-mortem. Lecture 4

  12. Number of Workdays: T • The number of full-equivalent working days for fork to dcut. • Subtracts • Weekends • Statutory holidays • “Company Days” • Subtracts anything we know in advance that nobody is expected to work. Lecture 4

  13. Developer Power: N • The average number of dedicated developers per workday working during the T-day period. • Dedicated Developer? Lecture 4

  14. Work Time & Dedicated Time • Work Time or Body Time • Defined as 8 hours per workday • Excludes weekends, stat. holidays, vacation entitlement. • E.g., 9-to-6 with 1 hour for lunch. • Dedicated Time • Uninterrupted hour equivalents. • Time dedicated to adding new features to the release. • Uninterrupted Time • 4 hrs with 30 min. of constant interruptions • Not 3.5 hrs of dedicated uninterrupted time – more like 2 • 2 hrs with NO interruptions at all Lecture 4

  15. Examples of Dedicated Losses • Maintenance (tracking down and fixing defects) on previous releases • Other simultaneous projects • Team-leader duties (& helping others) • Meetings • Training • Unexpected, non-made-up days off (e.g., sick days) • Sales/marketing support • Loss of flow due to interruptions Lecture 4

  16. Measuring N • Assume each developer understands the concept of a dedicated uninterrupted hour. • Get each of the n developers to record how many dedicated uninterrupted hours they spent in total during the coding phase. • hi is what’s in the time tracking system for the ithdeveloper. Lecture 4

  17. Attributing N • diis the number of days available during the coding phase • vi is the number of vacation days they took during the coding phase • hiis as before Substitute to get back to: Lecture 4

  18. Example • Bob called in sick for 2 days: accounted for in h • Bob took an afternoon off, but worked on the weekend to make up for it: accounted for in h Lecture 4

  19. Features Features fk = dedicated hours / 8 it took to code the kth feature. Lecture 4

  20. Post-Mortem • Imagine a time-tracking system that could track • hi,k,d • dedicated (uninterrupted) hours spent • by the ith developer • on the dth day • doing coding work on the kth feature • each such quantum would appear on both sides of F= N x T constraining them to be equal. • See section 5.10 in book for proof. Lecture 4

  21. Example Release Plan • Sample Deterministic Release Plan Lecture 4

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