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Project Planning using Little’s
Law
Dimitar Bakardzhiev
Managing Partner
Taller Technologies Bulgaria
@dimiterbak
In Kanban a project is a batch of
work items each representing
independent customer value that
must be delivered at or bef...
Why project definition says “work
items each delivering independent
customer value”?
Because we have data for “work items ...
When planning a project
• You need to provide some idea as to when the project
is going to be delivered.
• You need to pro...
Little’s Law for production systems
Little’s Law applies to any system, and
particularly, it applies to systems

within systems
Little’s Law holds in case of a project
1. We must have conservation of Flow
The average output or departure rate (TH) equ...
Little’s Law can help us calculate the
average Lead Time for a work item.
But we need a relationship between
the average L...
A Kanban system is a queuing system!
We measure Lead Time
Visual kanban system
Input Queue
WIP 2

Development

Test

WIP 5

WIP 4

Project Backlog

QA
NO WIP

DEPLOYED!
Average throughput of the project
system equals the average throughput
of the development system!
Using mathematical notation
Calculating Lead time for the project :
Number of developers we will need:
Examples
Calculating delivery date
Budgeting a project
Calculated delivery time should be
used only for the second leg of the Zcurve!
Z-curve
When calculating Project lead time we
need to:
• Account for the other two legs of the Z-curve
• Account for Dark Matter
•...
Planned Project lead time is the sum
of the calculated project length and a

project buffer
The two essential measurements of
project performance are the

percentage of the project completed
and the amount of the p...
Buffer consumption
Project Buffer calculation
Percentage of the project completed
Project buffer consumption
FAQ
If we have TH data for the Dev
System why don’t apply LL directly?
TH of Dev system is achieved using a certain WIP limit ...
Why don’t we use TH of the all three
Z-curve legs?
Because only the second Z-curve leg is representative for
the Dev Syste...
If or not the S/Z-curve applies to any
batch or just projects?
Project Planning using Little’s Law
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Project Planning using Little’s Law

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Project Planning using Little’s Law

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Project Planning using Little’s Law

  1. 1. Project Planning using Little’s Law Dimitar Bakardzhiev Managing Partner Taller Technologies Bulgaria @dimiterbak
  2. 2. In Kanban a project is a batch of work items each representing independent customer value that must be delivered at or before a certain date
  3. 3. Why project definition says “work items each delivering independent customer value”? Because we have data for “work items each delivering independent customer value”. A project is just a batch taken out from the flow of work. Say the flow processes thousands of work items. We can name a batch of a 100 work items “a project” but we have data for the flow itself and we use that data!
  4. 4. When planning a project • You need to provide some idea as to when the project is going to be delivered. • You need to provide a quote to the customer of how much the project will cost so she can decide whether to commit or not.
  5. 5. Little’s Law for production systems
  6. 6. Little’s Law applies to any system, and particularly, it applies to systems within systems
  7. 7. Little’s Law holds in case of a project 1. We must have conservation of Flow The average output or departure rate (TH) equals the average input or arrival rate (λ) There are no work items that get lost or never depart from the system 2. The system must occasionally empty, i.e., WIP = 0 Both are true!
  8. 8. Little’s Law can help us calculate the average Lead Time for a work item. But we need a relationship between the average Lead Time for a work item and the finite time period over which the project will be delivered!
  9. 9. A Kanban system is a queuing system!
  10. 10. We measure Lead Time
  11. 11. Visual kanban system Input Queue WIP 2 Development Test WIP 5 WIP 4 Project Backlog QA NO WIP DEPLOYED!
  12. 12. Average throughput of the project system equals the average throughput of the development system!
  13. 13. Using mathematical notation
  14. 14. Calculating Lead time for the project :
  15. 15. Number of developers we will need:
  16. 16. Examples
  17. 17. Calculating delivery date
  18. 18. Budgeting a project
  19. 19. Calculated delivery time should be used only for the second leg of the Zcurve!
  20. 20. Z-curve
  21. 21. When calculating Project lead time we need to: • Account for the other two legs of the Z-curve • Account for Dark Matter • Account for Failure load
  22. 22. Planned Project lead time is the sum of the calculated project length and a project buffer
  23. 23. The two essential measurements of project performance are the percentage of the project completed and the amount of the project buffer consumed.
  24. 24. Buffer consumption
  25. 25. Project Buffer calculation
  26. 26. Percentage of the project completed
  27. 27. Project buffer consumption
  28. 28. FAQ
  29. 29. If we have TH data for the Dev System why don’t apply LL directly? TH of Dev system is achieved using a certain WIP limit – say 5 work items of which say 2 in Dev Queue. We don’t know what TH of Dev System will be for WIP=10 work items.
  30. 30. Why don’t we use TH of the all three Z-curve legs? Because only the second Z-curve leg is representative for the Dev System capability. First and third Z-curve legs are project specific and show special cause variations. We protect the project delivery date from special cause variation using a project buffer.
  31. 31. If or not the S/Z-curve applies to any batch or just projects?

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