Kanban: Why It Works - SoftTech.ph 2014

What It Is, and Why It Works

Lorenzo DeeVP of Consulting, O&BSoftTech.ph 2014

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Source: commons.wikimedia.org

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Source: 75 Years of Toyota

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Source: 75 Years of Toyota

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Source: http://en.wikipedia.org/wiki/Tokyo_Imperial_Palace

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Source: http://www.shawcat.com/2014/02/higashigyoen.html

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Source: http://jumpingforjapan.blogspot.com/2012/08/the-ooku-land-of-gardens-and-sprouts-3.html

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Source: What can traffic in stockholm teach you about your development process by Håkan Forss

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Kanban is a method for managing knowledge work with an emphasis onjust-in-time delivery while not overloading the team members.

In this approach, the process, from definition of a task to its delivery to thecustomer, is displayed for participants to see and team members pullwork from a queue.

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Source: Wikipedia

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Kanban can be divided into two parts:

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Kanban system (small "k")

The Kanban method (capital "K")

Source: Wikipedia

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The word "kanban" (small "k") refers to (看板).

A "kanban system" (small "k") refers to a pull system implemented with(virtual) . A visual process management system that tellswhat to produce, when to produce it, and how much to produce.

The "Kanban Method" (capital "K") (as formulated by David J. Anderson) is anapproach to incremental, evolutionary process and systems change fororganizations. It uses a as thecore mechanism to expose system operation (or process) problems andstimulate collaboration to continuously improve the system.

Source: Kanban: Successful Evoluoutionary Change for Your Technology Business by David J. Anderson

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To summarize, the Kanban method:

to continously improve the system.

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uses a "pull" system,

limits work-in-process,

and exposes (or displays visually) the system operation (problems),

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Why use a "pull" system?

Why limit WIP (Work-In-Process)?

Why expose the process for all participants to see? Why make it visible?

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Source: http://www.funnystuff.today/2013/12/push-if-that-doesn-work-pull.html

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Push System

Pull System

Resources are provided to the consumer based on forecasts or schedules.

Make all we can (just-in-case).

A method of controlling the flow of resources by replacing only what hasbeen consumed.

Make what's needed when we need it (just-in-time).

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Balances demand against throughput

Eliminates (reduces) waste

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If you are working on something exciting that

you really care about, you don't have to be

pushed. The vision pulls you.

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Steve Jobs (1955 - 2011)

Apple

(emphasis added)

Little's Law:

L = average number of users in the system

λ = rate at which users arrive in the system

W = average waiting time that a user spends in the system

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Little's Law:

Let's say, at a store, customers arrive at a rate of 10 per hour, and...

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Little's Law:

Let's say, at a store, customers arrive at a rate of 10 per hour, and stay anaverage of 0.5 hours.

Based on Little's Law, we should find that the average number of customers inthe store at any time to be...

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Little's Law:

Let's say, at a store, customers arrive at a rate of 10 per hour, and stay anaverage of 0.5 hours.

Based on Little's Law, we should find that the average number of customers in

the store at any time to be 5.

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Little's Law:

L = average number of users in the system

λ = rate at which users arrive in the system

W = average waiting time that a user spends in the system

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Little's Law:

L = average number of users in the system (work-in-process)

λ = rate at which users arrive in the system (throughput)

W = average waiting time (or cycle time) that a user spends in the system

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To improve cycle time, only two options are available:

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Increase throughput

Reduce WIP

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What does WIP reduction have to do with software development?

There is causation between quantity of WIP

and average lead time (or cycle time), and the

relationship is linear.

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David J. Anderson, p. 27,

Kanban: Successful Evoluoutionary Change for Your Technology Business

Longer lead times seem to be associated with

significantly poorer quality.

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David J. Anderson, p. 27,

Kanban: Successful Evoluoutionary Change for Your Technology Business

In fact, an approximately six-and-a-half times

increase in average lead time resulted in a

greater than 30-fold increase in initial defects.

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David J. Anderson, p. 27,

Kanban: Successful Evoluoutionary Change for Your Technology Business

However, at the time of writing there is no

scientific evidence to back up this empirically

observed result.

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David J. Anderson, p. 28,

Kanban: Successful Evoluoutionary Change for Your Technology Business

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Source: http://blog.codinghorror.com/the-multi-tasking-myth/

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Source: http://www.enmast.com/2013/12/effects-of-multitasking/

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Limiting WIP limits cycle time and average lead time

Increased lead times lead to increase in initial defects and poorer quality

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Source: Scrum and XP from the Trenches, by Henrik Kniberg

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Source: Scrum team converts to Kanban

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Source: www.crips.se/kanban/example

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Source: Slack Time

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Source: Slack Time

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Source: Slack Time

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Source: Slack Time

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Allows everyone see the system (and its bottlenecks if any)

Allows the team to self-organize earlier

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To summarize, the Kanban method works because:

to continously improve the system.

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it uses a "pull" system,

limits work-in-process,

and exposes (or displays visually) the system operation (problems)

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