Kanban Cycle time and Little’s Law

First of all, I want to talk about Little’s law
The average number of work items in a stable system
is equal to their average completion rate, multiplied
by their average time in the system John Little, 1961

By solving this simple formula you are able to solve the
average time for work items in your system.

My closet provides a very good stable system example to
illustrate how you can apply Little’s law to track the average
cycle time.

My closet


Buying T-Shirts is one of my favourite hobbies, but I follow a rule,
I never buy a T-Shirt if I have the closet full (I only have space for 12).
Then I buy a new one and added to my closet. My closet is a stable system:
the rate at which T-Shirt enters the closet is the rate at which T-Shirt gets old.
Only 1 T-Shirt per month so per year, I buy 12 T-Shirt.
So, what is the average time for a book in my bookstore?

Let’s use Little’s law

Average number of work items in a stable system  =
Average completion rate X Average time in the system

Using my closet terms

12 T-Shirt = 6 T-Shirt / year (to finish reading) X
Average time in the bookstore.

Thus, the average time a T-Shirt is in my closet is 2 years

Mario Lucero

Mario Lucero

I am all about helping companies to adopt agile as methodology in Chile.


I believe many organizations think that agile is not for Chilean companies because of Chilean culture is totally
different from i.e. USA culture but I worked with Chilean professionals who after using agile realized it is feasible
to implement it.

Agile works in small and large projects and there are many evidences which demonstrate this.

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