Interpreting the Cumulative Flow Diagram

Posted on October 8th, 2009 in Agile, Kanban by siddharta || 2 Comments

The cumulative flow chart is a power packed graph that can show you a number of important metrics in a single graph.

Here is how to figure out everything that the graph is telling you

The cumulative flow graph has a lot of information made visible in a single image. Unfortunately, most people doing agile use the burndown chart exclusively and remain oblivious to the benefits of the cumulative flow graph.

Interpreting the cumulative flow graph

Key to harnessing the full power of the graph is to be able to interpret it. What  you see below is a cumulative flow graph generated in Silver Catalyst.

Cumulative Flow Graph

The graph shows the trend of the number of tasks (work items) in each stage of the workflow.

  1. As you can see above, the total number of tasks has increased from about 12 on 18th July to 20 on the 21st of July. This represents the scope creep between those days.
  2. The height of a segment on a given day denotes the number of tasks in that workflow state on that day. Using this we can figure out the size of the backlog on any day. We can also answer the related trend question – is the size of the backlog increasing or decreasing over time, and how fast.
  3. In a similar way, we can calculate the amount of work in progress, and its trend. Ideally we want to keep the work in progress low, even within a sprint.
  4. Finally, adding up everything except the final workflow state gives us the amount and trend of items that have not been deployed yet. This gives an indicator of a common pattern that occurs within scrum teams: Work items that are ‘complete’ within a sprint but are not deployed until much later. The problem with that is that potential feedback is also delayed, leading to teams having to redo features that were thought to be done much earlier.

A few benefits of cumulative flow graphs over the standard burndown chart

  1. It is a lot more informative. A single graph can give you a lot of information on the process.
  2. While the burndown chart shows only work remaining, the cumulative flow further breaks it down by workflow state.
  3. The graph handles scope increases naturally. The regular burndown chart does not depict scope change well, and although there are variations to allow scope change to be shown, none of them seem natural.
  4. The cumulative flow graph is not bound by sprint boundaries. You can view it for any time period, even across sprints.
  5. In a later post I’ll write about how you can use the CFG to perform more detailed analysis such as identifying bottlenecks and measuring lead time. You can’t do this with burndown charts.

A couple of downsides to the cumulative flow graph

  1. The CFG is information dense, so it is harder for a beginner to understand and interpret.
  2. CFGs are a lot harder to maintain by hand. Shameless plug: tools can help :)

In all, I find the burndown chart to be ideal to view progress within a sprint, while cumulative flow graphs are a good fit to track progress across sprints and to identify process level metrics (WIP, bottlenecks etc).

Doing Distributed Agile?

Share and collaborate with distributed teams with our electronic agile board tools. Get all the benefits of electronic tools without sacrificing the benefits of physical boards. Supports Scrum taskboards, Kanban boards and user story maps. Check it out!

2 Responses to “Interpreting the Cumulative Flow Diagram”

  1. Amanda Says:

    Hi Siddharta, in this post you wrote:
    “In a later post I’ll write about how you can use the CFG to perform more detailed analysis such as identifying bottlenecks and measuring lead time. You can’t do this with burndown charts.”

    Have you ever published this post about bottlenecks and lead time? Thank you

  2. siddharta Says:

    Hi Amanda,

    No I didn’t, but now that you mention it, it would be a good topic for my next blog post. Stay tuned.

Leave a Reply