Burn down charts are only half the story
For a long time we only used burn down charts when producing weekly highlight reports for the team and product owner. They served us well. For the first time in project delivery we had a clear, straightforward, simple chart that was quick to produce and everyone understood what it meant. You took your total story points in the backlog (x) subtracted the total number of points delivered on your iteration (y) to give you your new total points remaining (z). Rinse and repeat.
example burn down chart from easyBacklog
It wasn't until we worked on a farly large project for a financial institution that we noticed something strange. Our burn downs began to flatline for some sprints, even though we were delivering points. We quickly identified the reason; in agreement with the client we were adding stories (points) to the backlog, so the points we were delivering for a sprint were being cancelled out by the ones being added. Net result the burn down flatlined.
This is when the true value of burn ups began to emerge. A burn up as it name suggests starts from zero and you simply add the number of points delivered in each iteration to the last number. Sounds like a burn down in reverse right? Wrong. What differs with the burn up is that it also has a target number that you are aiming for (the backlog total shown in blue below) and more importantly this total can go up or down and is reflected in the graph.
example burn up chart from easybacklog showing points were added to the backlog during interation 2 and 4 and 5
This means:
We see the number of points delivered in each sprint
We clearly see if points are added or taken away from the backlog total
We can add a trend line up to the backlog total to see how many sprints it will take to deliver all the points
With easyBacklog both burn up and burn down are calculated automatically for you and appear within the stats tab. So give it a go and tell us what you think.