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Unleash developer productivity with cumulative flow charts
Published:Nov 10, 2023

Unleash developer productivity with cumulative flow charts

Leading a successful team requires more than having great products and services. 

You also need to stay on top of your operations and ensure everything goes smoothly. You have to plan things out, anticipate bottlenecks, and make strategic decisions about where to focus your efforts. 

A handy method for this? 

Cumulative flow diagrams (CFDs). 

These diagrams enable Agile teams to monitor workflows, predict disruptions, and achieve higher efficiency. 

A cumulative flow diagram (or chart) displays the number of tasks in each stage, from initiation through completion. As a result, it can help you determine what’s working, what’s not, and which tasks or projects to prioritize. 

The challenge lies in reading the diagram. Each color on the chart has a different meaning, and you need to know how to interpret that data. This requires a thorough understanding of the Kanban framework and specific metrics, such as lead time and work in progress (WIP). 

What is a cumulative flow diagram?

Have you ever been asked to give an update on a project? 

Then you know it can take hours to get all the data in one place. Plus, you may need to explain what stage each task is at and how long it will take to complete it.

A cumulative flow diagram can make things easier by displaying the amount of work at each stage of the process.

Cumulative flow diagranm

At the same time, it provides the data you need to identify any bottlenecks, inefficiencies, or distractions that may be slowing you down. 

Cumulative flow charts have a lot of similarities to a burn up chart, but it offers a more granular view — making it especially effective in situations that demand a deeper analysis of workflow dynamics.

It is a visual representation of your overall project progress and workflows. You can see the volume of work that has been completed since a project began, and then use this data to measure and improve your team’s productivity. 

Where does it fit into the Kanban method? 

CFDs are often used along with Kanban boards to visualize and manage ongoing projects. 

A Kanban board lets you see the work in progress, or the tasks you need to tick off your list to complete a project. Its role is to help Agile, DevOps, and other creative teams improve their workflows, stay organized, and reduce waste. 

Kanban boards can be physical or digital and have three or more columns.  A basic Kanban  will have at least these three steps:

  • To do
  • In progress
  • Done
Kanban board

With a physical board, you use color-coded cards to track the tasks listed in each column. As the project progresses, you move the cards from one column to the next. 

If you opt for a digital board, you use virtual cards representing tasks and assignments. 

Cumulative flow charts are derived from the data on a Kanban board. Agile teams can use CFDs to see how their work progresses over time, and Kanban boards to manage current work. 

Both apps can help improve software development productivity and decision-making, leading to better project outcomes. 

How to monitor project progress with CFDs

When you’re a developer, it can be hard to tell which productivity metrics you should use and which ones to ignore. 

For example, the metric Lines of Code (LOC) says nothing about a project’s progress. More lines of code don’t necessarily mean better code or higher productivity. 

Instead, create a cumulative flow diagram to visualize these three critical metrics:

  • Work in progress (WIP): The number of tasks your team members are working on 
  • Cycle time: The time needed to complete each task
  • Throughput: The number of tasks or work items completed over a given time period 

Let’s say your team is constantly missing deadlines. In this case, you could set WIP limits for each phase of the project to sustain an efficient workflow. 

Project managers can also implement WIP limits to prevent duplicate work, reduce multitasking, and identify bottlenecks. 

With this approach, your team will focus on quality rather than quantity and understand what’s keeping them from making progress. Plus, you’ll be better able to measure productivity vs efficiency and estimate completion times more accurately. 

Throughput, on the other hand, enables you to measure your team’s performance. 

For instance, you can track throughput over several months to see what you do well and what could be improved. 

This data helps you to identify the best people for the job and set realistic project timelines. In the long run, it can lead to better collaboration, higher efficiency, and improved client relationships. 

How to read a cumulative flow diagram

Cumulative flow diagrams have several colored bands, two axes, and other elements, depending on what you want to track. 

Let’s see what these mean:

  • Vertical (y) axis: The number of work items, or user stories, in your product backlog at any given time
  • Horizontal (x) axis: This is basically a timeline, with the earliest point on the left and the most recent on the right. It shows how your tasks have moved through the stages of the process over time.
  • Colored bands: The stages of your workflow. Each band illustrates a different stage of the task or process you’re working on (e.g., Not started, Design, Coding, Testing, and Complete).
Elements of a cumulative flow diagram

CFDs can have different layouts but will always include an X-axis, a Y-axis, and color-coded bands. To read the diagram, check the size of the colored areas over a given period, such as the current week or the last six months.

If, say, the color-coded bands are progressing in parallel, then your throughput is stable. 

But if one or more bands are widening, the number of tasks coming in is higher than the number of tasks completed. In this case, you may be dealing with bottlenecks, distractions, or inefficiencies. 

What you should do is figure out the problem and complete any work in progress before taking on new tasks. 

Narrowing bands indicate that you’re focusing too much on some tasks and too little on others. Therefore, you should balance out your workload and adjust the WIP limits.

You can also measure the horizontal distance between the top line and bottom line of the diagram to determine the average cycle time. This metric indicates how long it takes to complete a task from start to finish (e.g., from “Not started” or “To be started” to “Done”).

What should it look like? 

If your team’s throughput is stable and consistent, the diagram will be smooth from left to right. 

The color-coded bands will stay more or less even, except for those representing the work completed, which should get wider over time. Any abnormal patterns indicate potential issues that require your attention.

Example of throughput is stable and not stable

However, in some cases, you may notice changes that don’t necessarily pinpoint bottlenecks. 

For example, Scrum teams use sprints, or development iterations, to complete specific tasks within a short period. 

Therefore, the curves illustrated on the diagram may increase rapidly toward the end of a project, such as when your team is testing a product before launch. See our guide to iteration management to learn more. 

Sometimes, the curves flatten out over several days or weeks. You may notice this trend when the company is closed, such as during holidays. That’s perfectly normal, so you have nothing to worry about. 

The same can happen when your staff is working on a different project. But if that’s not the case, you may be dealing with bottlenecks.

How does a cumulative flow diagram differ from other charts?

As mentioned earlier, cumulative flow diagrams are similar to but more complex than burn up charts. But what’s the difference between the two?

Both enable stakeholders to track project progress, but burn up charts are used to compare the work completed against the total amount of work. 

The chart has a vertical axis, a horizontal axis, and two color-coded lines. The green line represents the work completed so far, while the gray line shows the total project backlog. 

Most teams use burnup charts to measure progress toward a goal. 

But if you want to see how much work is left to do, you’ll use a burndown chart. This app also shows how much time you need to complete a given task. 

Burndown charts can help you determine whether your team is ahead of or behind schedule. They also provide data that can be used to measure sprint progress, velocity, and other Agile KPIs

Burn up and burndown charts are not as detailed as CFDs, but you should still integrate them into your workflows.

Burn up and burndown charts

They’re easier to create and interpret than an Agile cumulative flow diagram, offering quick insights into project progress. Plus, they can help your team identify potential issues early in a sprint or project. 

Potential limitations and drawbacks 

Like other analytical apps, CFDs have their limitations and are not suitable for every project. 

For example, they don’t take into consideration external dependencies and other factors affecting the flow of work. 

If someone on your team gets sick, for example, the project may stagnate until they come back to work. A few weeks later, you encounter some technical issues that cause project delays. 

As a result, you may notice an increase in the WIP or other unwanted changes, such as lower throughput. However, the diagram won’t show what caused these changes, so you’ll have to check your records. 

On a similar note, CFDs cannot provide insights into the root cause of bottlenecks. In some cases, you might end up spending weeks trying to figure out the problem. 

Additionally, CFDs assume a steady-state process, which may not work for teams with changing needs (e.g., startup teams that are constantly testing new technologies and ways of working). 

Another drawback is that the diagram can be complex and hard to interpret when you’re tracking projects with numerous stages. The same can happen when there is a high degree of variability in work items. 

Given these aspects, it’s best to use CFDs along with Kanban boards and other apps. You’ll also want to incorporate additional data and context into your analysis and employ other Agile practices, such as sprint retrospectives, for further insights. 

Measure and maximize developer productivity with the right apps 

Cumulative flow diagrams can streamline your processes and drive productivity. They also make it possible for you to spot bottlenecks quickly and monitor throughput, making it easier to stay on top of your projects. 

For deeper insights, use them along with the best Agile reporting apps for software teams.

An example is 7pace, which enables teams to track the time spent on tasks and projects and generate reports in seconds. With this data, you can better monitor your team’s performance and ensure timely project delivery.

Learn more about how 7pace can streamline teamwork and project planning.

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