How to Use a Cumulative Flow Diagram in Practice

Time to spot the bottlenecks

When it’s time to take control of the workflow and make informed decisions that drive efficiency and productivity, a cumulative flow diagram (CFD) comes with help. This powerful tool provides you with a visual representation of work progression, helps to identify bottlenecks, and enables continuous process improvement.

Learn how to use this tool in practice.

What is a cumulative flow diagram?

A Cumulative Flow Diagram (CFD) is a visual tool used in project management, particularly within Agile and Lean methodologies, to track and analyze the flow of work through different stages of a process over time. It is especially useful in Kanban and other iterative work systems. 

Components of a cumulative flow diagram

Axes:

• Vertical Axis (Y-axis): Represents the cumulative number of work items (like tasks, user stories, features, etc.). It shows how many items are present in the workflow at any given point.
• Horizontal Axis (X-axis): Indicates the passage of time, typically marked in days, weeks, or sprints.

Color-Coded bands or layers:

Each band corresponds to a different stage or status in the workflow (e.g., To Do, In Progress, Testing, Done).

The bands are stacked on top of each other, and the width of each band at a given point on the X-axis represents the number of items in that stage at that time.

Work in Progress (WIP) levels:

The middle parts of the diagram, usually representing the "In Progress" stages, show the amount of work currently being handled. The thickness of these bands indicates the volume of WIP.

Lead Time and Cycle Time indicators:

• Lead Time: This can be observed by tracking the horizontal distance from the point where an item enters the system (e.g., added to the backlog) to the point where it is completed.
• Cycle Time: Measured by the horizontal distance from when work begins on an item (typically entering an "In Progress" stage) to its completion.

Bottleneck identification:

By observing the expansion and contraction of bands, you can identify bottlenecks in the workflow. A widening band indicates a growing backlog in that stage.

Trend lines:

Some CFDs include trend lines that help in forecasting and assessing the health of the workflow over time.

Data points:

Actual data points or markers may be used to represent specific metrics or events, providing more detailed insights into the workflow process.

How development teams benefit from using cumulative flow diagram

The question is: how can you actually use a cumulative flow diagram? Development teams can reap significant benefits from using Cumulative Flow Diagrams (CFDs) as part of their project management and workflow analysis. 

Identifying bottlenecks

CFDs make it easier to spot bottlenecks in the development process. A widening band in the diagram indicates a growing amount of work in a particular stage, signaling a potential bottleneck. Identifying these early allows teams to address issues before they become major blockers.

Monitoring Work in Progress (WIP)

CFDs help in managing and optimizing WIP levels. By visualizing how much work is at each stage, teams can avoid overburdening certain stages of development, leading to more efficient workflow management.

Improving process efficiency

By analyzing trends in the flow of work, teams can identify inefficiencies in their processes. This can lead to process improvements that increase productivity and reduce waste.

Predicting project completion

CFDs allow teams to forecast project timelines more accurately by analyzing the flow rates and trends. This helps in setting realistic expectations with stakeholders and in planning future projects.

Balancing resources

By observing how work moves through the different stages, teams can better allocate resources and personnel. This ensures that no part of the process is understaffed or overburdened, leading to a more balanced and efficient workflow.

Enhancing communication and transparency

CFDs provide a clear and easy-to-understand visual representation of the project status, which is useful in communicating with team members and stakeholders. It promotes transparency and a shared understanding of the project's progress and challenges.

Tracking Lead and Cycle Times

The diagram helps in monitoring the lead time (from work item initiation to completion) and cycle time (time to complete a work item once it's started). Understanding these metrics is crucial for continuous improvement and efficiency.

Facilitating continuous improvement

Regular analysis of CFDs encourages a culture of continuous improvement. Teams can use insights gained from these diagrams to make iterative changes to their processes, thereby improving overall performance over time.

How to read a cumulative flow diagram?

Understand the axes:

• Vertical Axis (Y-axis): This axis represents the cumulative number of work items (tasks, user stories, etc.).
• Horizontal Axis (X-axis): This axis shows time, which could be in days, weeks, or sprints.

Examine the color-coded bands:

Each band or layer of the diagram represents a different stage in the workflow (e.g., To Do, In Progress, Testing, Done).

The width of each band at any point on the X-axis shows how many items are in that stage at that time.

Look for trends in the bands:

• Widening bands: If a band is getting wider over time, it means more items are entering that stage than leaving, potentially indicating a bottleneck.
• Narrowing bands: A narrowing band suggests that items are moving through that stage efficiently.

Identify Work in Progress (WIP):

Focus on the middle bands that typically represent the active work stages. The thickness of these bands indicates the WIP levels.

Assess Lead and Cycle Times:

• Lead Time: Observe the time it takes for an item to move from the entry point of the system (often the bottom band) to the completion stage (top band).
• Cycle Time: Measure the time it takes for items to move through the main workflow stages (typically from when they start being worked on to completion).

How to use a cumulative flow diagram in practice?

Step 1: create the diagram

• Identify workflow stages: Define the stages of your workflow (e.g., Backlog, To Do, In Progress, Testing, Done). These will form the different colored bands in your CFD.
• Collect data: Gather data on the number of tasks or work items in each stage over a period. This data is often automatically tracked in project management software.
• Plot the data: On the vertical axis, represent the cumulative count of tasks. The horizontal axis represents time (days, weeks, etc.). Plot the cumulative number of tasks in each stage against time.

Step 2: analyze Work in Progress (WIP):

Observe the width of the bands representing the "In Progress" stages. If a band is widening over time, it indicates an accumulation of work and potential bottlenecks.

Step 3: analyze the flow:

A smooth, consistent upward flow of bands indicates a healthy, stable process.

Jumps or breaks in the bands can indicate issues or changes in the process.

Step 4: check for consistency:

Consistent, parallel bands suggest a stable and predictable workflow.

Significant fluctuations in band widths might indicate process instability or variability in work intake or delivery.

Step 5: use as a forecasting tool:

By analyzing past trends, you can predict future workflow and identify potential capacity issues or delivery timelines.

Step 6: identify bottlenecks and blockages:

Look for stages where work seems to pile up, indicating a slowdown in the workflow. Addressing these bottlenecks is crucial for maintaining a smooth flow of work.

Step 7: monitor Lead Time and Cycle Time:

Use the diagram to track how long it takes for work items to move from start to finish (lead time) and the time spent actively working on them (cycle time).

Step 8: assess workflow balance:

Determine if work is evenly distributed across stages. Imbalances might require adjustments in resource allocation or process changes.

Step 9: continuous improvement:

Regularly review the CFD to identify areas for process improvement. Iterative changes based on CFD analysis can lead to enhanced efficiency and productivity.

Next steps

CFD is a dynamic tool that reflects the ongoing changes in a project. Regularly reviewing and analyzing the CFD is crucial for maintaining an efficient workflow and addressing issues proactively. It's not just about what the diagram looks like at a single point in time, but how it evolves over the course of the project.

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