We use Burn Down charts to illustrate our task completion status in the Scrum world. However, if you’re still using hours to estimate your user stories/tasks, are you using the burn down chart in an appropriate way? Is your Burn Down chart really demonstrating your current progress and team velocity?
Let’s look at the below example.
Assume we’re running 5-days sprints, and before we start each sprint we have a sprint planning session in which we break user stories down to tasks and give the original estimates (hours) for each task. When time goes by we record two metrics data everyday – hours spent on each task, and the newly estimated remaining hours for each task.
In this case what do you feel if look at the burn down chart below?
I bet you’ll feel everything ‘s just going well, although we still have 2 hours at the end of the Sprint, it looks like it’s not a big deal, we’re still on track, we’re good.
But if you take a second look at the data sheet where this burn down came from, you probably will have a different view– every user story contains one unfinished task, with only 0.5 hour left. Although the estimation for the total work remaining is just 2 hours it still results in zero delivery in this Sprint. Nothing at all would be delivered, and that would be a significant failure. The Burn Down chart lied to you.
How can we fix this problem? How can we make sure the Burn Down chart represents your real progress?
Solution 1: use Story Points instead of hours when estimating
When using Story Points for estimation, the points can be “burned” only when the task is marked as done. That can help highlight the unfinished tasks/stories on our Burn Down chart because the trend will be magnified when not calculating those “In Progress” efforts. Below is an example of using Story Point estimation with the exactly same task completion status. The result is quite close to the real situation.
Solution 2: create another “task completion Burn Down chart” in addition to your current estimation Burn Down chart, regardless of whether your Burn Down is based on hours or Story Points
If you put the “Tasks Burn Down Chart” and “Hours Burn Down Chart” side by side, they might provide you with more information to judge what the real completion status is.
I’ve been using both of these solutions in several projects. My personal favorite is to use a combination of “Task Burn Down” plus “Story Point Burn Down”. They always tell me the real task completion status and never lie to me. 🙂
