- The Kanban board is a great tool
to see the amount of work
that's being pulled through the system.
You have your different work queues,
and the Kanban cards represent
batches of work in the queues.
Remember that one of the key benefits to Kanban
is that it gives you a way to measure and manage your flow.
One of the key challenges with the Kanban wall
is that it only gives you the ability
to measure and manage work that's currently on the board.
But, to make lasting improvements
you have to see how work flows through the system over time.
That's why Kanban teams often use
something called a cumulative flow diagram.
The way you should think about a cumulative flow diagram
is that it takes the Kanban wall,
and gives each column a color background.
That means that each queue will have a different color.
Then, the cumulative flow diagram
tilts the Kanban wall on its side,
so it looks like a multi-colored layer cake.
Then, the diagram creates an x and y axis.
The upright, or y axis, typically represents
the number of Kanban cards that your team completed.
The horizontal, or x axis, represents the units of time.
These are usually labeled as months.
The very first month
is when you started working on your product.
As you can imagine, the cumulative flow diagram
typically slopes upward.
That means that when the team first starts working,
they won't finish many cards.
Oven time they complete more and more
until they finish the product.
What makes things a little tricky
is that each queue will be thicker
based on the number of cards that they've completed.
When you start working on your product
you'll see a big bulge of Kanban cards in the input queue.
That means that you're spending the bulk of your time
figuring out the product's features.
Over time the input queue should shrink,
and the deploy queue should increase.
Say that your cumulative flow diagram looks like this.
You see a big, purple bulge
at the beginning of a steady slope,
but you don't see a similar sized bulge of the color red.
If you see this in the diagram,
that means that the development team is pulling
too much work through the system.
You'll either want to dial back
the development queue's WIP limit,
or you want to increase the testing team's capacity.
Ideally the team should have a steady cadence.
That means that you want your development,
testing, and deployment queues
to be all roughly about the same thickness.
It's normal to have your cumulative flow diagram
book-ended by two opposing work queues.
If you think about it, that makes a lot of sense.
Reading your cumulative flow diagram
is one of the key ways
to improve the flow of work through your system.
Look for these warning signs
as you look over this important graphic.