Comments on: Kanban requires similar sized stories? http://blog.jayanthan.com/2008/09/kanban-requires-similar-sized-stories/ jay padinjaredath's blog Mon, 13 Apr 2009 22:33:26 -0400 http://wordpress.org/?v=2.9.1 hourly 1 By: Does Agile use Kanban? « Tom Looy’s Weblog http://blog.jayanthan.com/2008/09/kanban-requires-similar-sized-stories/comment-page-1/#comment-12 Does Agile use Kanban? « Tom Looy’s Weblog Thu, 11 Sep 2008 17:54:28 +0000 http://blog.jayanthan.com/?p=17#comment-12 [...] Agile use Kanban? A friend recently asked the question ‘Do you have to have similar sized stories in order to make Kanban work in Agile?’  [...] [...] Agile use Kanban? A friend recently asked the question ‘Do you have to have similar sized stories in order to make Kanban work in Agile?’  [...]

]]> By: Tom Looy http://blog.jayanthan.com/2008/09/kanban-requires-similar-sized-stories/comment-page-1/#comment-10 Tom Looy Thu, 11 Sep 2008 03:14:17 +0000 http://blog.jayanthan.com/?p=17#comment-10 Kanban, as implemented in Lean Manufacturing, is part of a 'pull' system. In an ideal pull system when a unit is sold a signal is sent to the pull system to indicate that the system needs to manufacture the unit that has been sold. Often this signal is in the form of a card on a wall or billboard. ('Kanban' in Japanese actually means 'billboard'.) More often though, a Kanban system is used to trigger replenishing inventory when inventory in the workflow gets to be too low for the step in the workflow that is consuming the inventory. The use of Kanban in Agile really isn't a pull system though. In Agile, the Agile Wall is used to indicate work that is available but the work is pushed through the system and is waiting to be pulled by the next step in the workflow when they have cycles available to do the work. (The key word there is 'waiting' to be pulled.) So, although people pull work from the Agile Wall, the work was pushed onto the wall from previous step in the workflow. A better approach to keeping the system optimized is to not worry about keeping the size of the stories the same in order to keep the flow even, but rather use Theory of Constraints to make sure that the constraint in the system is never starved. Doing anything more than that has little effect on throughput so considering story size becomes a moot point. Kanban, as implemented in Lean Manufacturing, is part of a ‘pull’ system. In an ideal pull system when a unit is sold a signal is sent to the pull system to indicate that the system needs to manufacture the unit that has been sold. Often this signal is in the form of a card on a wall or billboard. (‘Kanban’ in Japanese actually means ‘billboard’.) More often though, a Kanban system is used to trigger replenishing inventory when inventory in the workflow gets to be too low for the step in the workflow that is consuming the inventory.

The use of Kanban in Agile really isn’t a pull system though. In Agile, the Agile Wall is used to indicate work that is available but the work is pushed through the system and is waiting to be pulled by the next step in the workflow when they have cycles available to do the work. (The key word there is ‘waiting’ to be pulled.) So, although people pull work from the Agile Wall, the work was pushed onto the wall from previous step in the workflow.

A better approach to keeping the system optimized is to not worry about keeping the size of the stories the same in order to keep the flow even, but rather use Theory of Constraints to make sure that the constraint in the system is never starved. Doing anything more than that has little effect on throughput so considering story size becomes a moot point.

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