Guide to Cumulative Flow Diagrams

Cumulative Flow Diagrams: A Cumulative Flow Diagram (CFD) is a visual tool used in Agile project management, particularly in Kanban, that shows the progress of work over time. It displays the total amount of work in different stages of your workflow with the area under each line representing the number of work items in that stage. It allows teams to track quantity of tasks and monitor whether there is accumulation of work or bottlenecks in the process, therefore enabling better strategic decision-making.

Importance: It enables Agile teams to visualize work in progress (WIP), identify bottlenecks, and predict project delivery times. By making work visible and providing a correlation with lead time, it provides a clear indication of the health of a project. It can also show if work is entering at a higher rate than it is leaving or if work takes too long to complete which results in longer delivery times.

How it works: The Y-axis of a CFD shows work items, and the X-axis denotes time. Each coloured band's thickness at a given point represents the quantity of WIP items at the corresponding stage of a process. Thus, displaying work item quantities distributed over time and showing the stability of the workflow.

Exam Tips: When interpreting CFDs, remember to look for a consistent gap between the bands, which denotes steady flow of work. If a band is getting wider, work is accumulating. Understand the difference between lead time and cycle time: lead time is from the moment you receive a task until it's done; cycle time is just the time when a task is actively being worked on. Expect questions that request diagnosis of a project’s status or its potential problems based on a provided CFD in the exam.