How to Preserve the Predictability of Your Workflow Using the Health Zones on the Aging Chart
The health zones on the Aging Chart will help you stay on track with your commitments and ultimately preserve the predictability of your system.
Often, we make the mistake of assuming that our projects will go ahead exactly as we planned. We forget that knowledge work, by its nature, is unpredictable. Lots of unexpected and surprising things happen all the time.
It’s crucial to put a finger on the pulse of the work and stay firmly on track as we make progress. If we do go off schedule, we need to understand the reasons behind our delays and take action on time. And that’s where the Aging Chart comes into play.
What Are the Health Zones on the Aging Chart Telling You?
The Aging Chart enables you to track your current tasks in progress. It uses the same visual format as your Kanban board, with each column representing a state in your workflow. The Aging Chart shows how many days a task has already spent in progress.
The colored zones in the chart are called health zones and they represent a timeline. They visualize the amount of time that your completed work items have spent in progress, as the work was moving through each process state.
The dark green zone at the bottom represents the timeline at which 30% of your completed work moved through the workflow. The light green zone visualizes the timeline of 50% of your previous work. Then, the yellow corresponds to 70%, the orange to 85% and the light red zone indicates the amount of time that 95% of your completed items took to be delivered.
If your dots are positioned above the light red zone, this means that your current tasks are spending more time in the process than 95% of your previously finished tasks spent in that specific state.
In the example above, the light green zone in the “Code review” state points to 6 days. This means that, by this point, 50% of our completed items spent up to 6 days in the workflow. We can see that there is an item in “Code review” that points to 3 days. It is still in the light green zone. This tells us that this specific item has taken less time (so far) than 50% of our previous work, so it’s moving predictably and within our expectations.
Let’s look into the item on the top of the “Testing” state. It is positioned on the border between the yellow and orange zone. This means that it has taken more time than 70% of our work in that process state.
If your dots go into the red zone at any point along the workflow, this means that they are taking significantly longer than your previous work items and you are going off track.
The lines stretching across the chart are called percentile lines. Both the percentiles and the health zones represent the exact same thing. The only difference is that the percentiles show you how much time your previous items spent in the workflow overall, while the health zones show that exact same information split by process state. That is why the percentile lines always line up to where the health zones end.
How to Get Back on Track While Enabling a Supportive Environment
Tracking the position of your work items throughout the health zones is a powerful strategy for preserving the consistency of your delivery times. It also helps you figure out whether you’re still on track with your commitments.
If you’ve committed to delivering an item within 11 days, and this comes with an 85% probability of achieving that promise, then the goal is to make sure your item doesn’t cross the 85th percentile. Ideally, your item should go through the workflow without crossing the red zones at any point along its lifecycle. If it does, then you can take action on time to ensure that you keep your promises.
Tools like the Burnup and the Burndown charts will also enable you to see whether or not you are still on schedule. But, to take a step further and understand the actual reason behind your delays, you should look into the factors that hinder your performance. Don’t fall into the trap of assuming things will go back on track if the team works hard enough.
The Aging Chart will help you head in the right direction and stay on schedule while enabling a supportive environment at the same time.
Let’s look into another example. The dot in the Testing (Done) state has already taken more time than 85% of the work we finished in the past. It is currently in a queue state. Queue states are used in Kanban pull systems to indicate that work items are ready to move forward. Queue states are passive; no one is working on items in queue states, the work is just staying and waiting to be handled.
So, instead of starting new work, the team should focus on this specific work item and initiate the deployment as soon as possible. To keep its cycle time within the threshold, they need to make sure it no longer accumulates waiting time in their system. That way, they will keep their overall cycle times consistent, just by changing how the team decides what to work on next.
To explore another simple pull strategy that achieved tremendous improvements in the Wizards’ delivery times in only two months, download the Wizards use case.
DOWNLOAD THE WIZARDS USE CASE IN PDF FORMAT
Use this PDF as a reference when assessing your explicit policies and evaluating the predictability of your delivery system.
The health zones in the Aging Chart will give you real-time feedback on whether you’re heading in the right direction. It will enable you to proactively avoid going beyond schedule and preserve the stability of your system.
Managing the flow of work effectively is the cornerstone to achieving sustainable predictability while enabling an environment of support, engagement and motivation.
If you’re interested in developing a stable delivery system, while building an environment of trust, respect and appreciation, I’d be thrilled to welcome you to our Sustainable Predictability program.
Meet the Author
Sonya Siderova is a passionate product manager and a driving force behind Nave, a Kanban analytics suite that helps teams improve their delivery speed through data-driven decision making. When she's not catering to her two little ones, you might find Sonya absorbed in a good heavyweight boxing match or behind a screen crafting a new blog post.