Kanban Metrics you won’t hate – Part 1: CFD – Cumulative Flow Diagram

If you have read the article of Annelies de Meyere about detailed metrics are not always the answer, you must think why this article? Well some metrics are good!!! It’s the best way to see how you're doing with your team. But as described in the article of Annelies over-metric is bad, it’s not a weapon to use against your team or one member. It’s not a weapon for your KPI’s. In this way you’re doing something wrong.

A small overview of Metrics – Good & Bad

Performance Based

e.g. Cycle Time

Compliance Based

e.g. LoC, personal Burndowns

So in this series of blogposts we will discuss a few metrics that are useful in Kanban.

The first metric is called Cumulative Flow Diagram (CFD).
CFD shows us how work accumulates in flow with time, and is very useful in forecasting projects and tells us a lot about the overal flow.

Let’s take a look at the following CFD:

The horizontal axe represents time, the vertical axe represents the number of tasks. The curves inside are the number of tasks in the different states you use on your kanban board. So in this case we have 3 states: Work todo, Work in Progress and Work done.

Keep in mind if you have too many states, first your board will be useless, but also the CFD will be useless.

Ok, that said, what do all these curves tells us?

  1. If the space between the curves “todo” and “in progress” is getting too thick, you have to check your Product Backlog (PB). You need to do some action on it, check if there aren't too many items in the todo state.
  2. If the space between the curves ‘in progress” and “done” is getting too thick, you should review and reset your WiP limits to a reasonable limit. They are set too high.
  3. If the space under the curve “done” is getting thicker, you're doing good. You get tasks to done.

When you have knowledge of this part, there’s more to discover. Let’s take a look at the following drawing.

We can find 4 area’s, all of them give us important information.

  1. Lead Time or Tactical Time: How much time is needed for a task going from ToDo to Done.
  2. Cycle Time or Operations Time: How long does it take for a task to go from WiP to Done.
  3. Backlog: How big is it. We have discussed this before. It will be visible when you have too much work in your backlog.
  4. WiP: How much work is the team doing at that moment. Here’s a bottleneck you will see directly. If you don’t use WiP Limits, it will be available here.

Wrap-up:

We could say the CFD gives us a lot of information. And you will find that a few patterns stand out in this metric:

  • Too much work in progress
  • If you have a testing state: Slow testing (are you using automated testing?)
  • A very long lead time and
  • A not changing backlog, which is strange. A backlog should change after a while because both the team and the Product Owner (PO) learn more about the product.

Stay tuned for a future article about another Kanban metric.

For more information on Kanban metrics and also how to use them on your personal Kanban, see the book "Personal Kanban in a Nutshell"