Keep track of your work in progress. Observe how much work your team delivers. Instantly spot bottlenecks.
In the Cumulative Flow Diagram (CFD), each colored area represents a list in your Kanban board. The horizontal axis shows a timeline and the vertical axis displays the number of tasks in your lists. The size of these colored areas indicates how many work items are currently on each list.
Strive to keep the number of tasks in progress within your WIP limits - this is the key to achieving a stable process.
By hovering over the graph, you can see the number of items in each process state on the selected date. You can also track the accumulated number of tasks completed, those in the ‘Done’ state, in the selected time frame.
You can switch between 'process' and 'states' in your WIP tooltip to see your total WIP or the WIP in each of the lists on your Kanban board.
The horizontal difference between the top and the bottom line of a CFD area at any point along the graph is your process's approximate average cycle time. The approximate average cycle time shows you how long it took, on average, for items to be completed on the selected day.
The comparison of the approximate average cycle time from your CFD with the exact average cycle time from your Cycle Time Scatterplot can give you a good understanding of your process performance. If the values are roughly equal, this means that you’re maintaining a stable system.
The bottom line of your CFD represents the ‘Done’ state of your process. By observing that line on the CFD, you can measure the total amount of work that your team has delivered. The slope of that line between any two points indicates your average throughput between those two points. A productive and self-organized team will be able to complete tasks quickly and so will see the ‘Done’ area grow rapidly.
Watch out for a flatter gradient in your ‘Done’ area! The slower it grows, the longer your delivery times are.
The top line of the graph represents the arrival rate of tasks, while the bottom line shows their departures. These are the rates at which you start new work and finish outstanding work.
In order to maintain a stable system, you need to monitor how these lines move over time. To achieve a predictable workflow, strive to keep your WIP as consistent as possible. If the WIP is consistent, the arrival rate and departure rate lines will grow in sync and the distance between them will stay equal.
The ‘Arrival & Throughput Rates’ widget on the Cumulative Flow Diagram enables you to track how your arrival and throughput rates change over time in the selected time frame. Ideally, the lines should overlap with each other.
If the arrival line goes up, this means that you’re starting work faster than you finish it and your team is working on more tasks than they are able to handle at a time. A higher arrival rate translates to increased WIP and usually results in increased cycle times, reduced team efficiency and potential delays.
The Cumulative Flow Diagram enables you to evaluate the stability of your system and helps you identify problem areas in order to achieve a predictable workflow and a healthy process. In a stable system, the average arrival rate is roughly equal to the average throughput rate. This means that the tasks arrive in the process at the same speed as they leave it.
Based on Little's Law, Average Cycle Time = Average Work In Progress / Average Throughput. The more accurate the equation, the healthier your process. If the math breaks down for you, it is time to take a closer look at your management practices.
The Cumulative Flow Diagram gives you instant insight into the exact amount of work in each state of your process. If one or more of the areas that represent WIP start expanding, it signifies a bottleneck in that state and a problem stemming from your workflow.
Remember to account for changes like team size or any public holidays before jumping to conclusions - these could provide explanations for unexpected spikes in your activity.