Burndown Charts 1: "Simple Burndown"

Burndown charts are used to communicate the progress of an Agile project clearly and quickly. They speak to scope, schedule and even budget (assuming the budget is enough to get you through the number of sprints included in the chart.) The chart isn't a status report, but is a key part of one.

With burndown charts, however, there is no one-size-fits-all. Simple charts communicate information quickly, but at the expense of important information. Complex charts provide more insights, but can be difficult to digest. This latter point is especially important if your audience is new to Agile approaches.

This means that you will have to figure out what works best for you and your stakeholders, and make it work.

That is the process I am going through right now, and I will post what I've developed along the way. The first post will look at...

Simple Burndown

The simple burndown chart shows how much work will get done before time (and money) run out.

Ideal Progress

The green dotted line is a straight line from the beginning of scope and time to the end of the project. This chart shows an 8 sprint project. The idea is that the blue "actual" line remains close to the ideal line. If reality isn't close to forecast, you have a problem. This will happen. That's why you're a Project Manager. Here is the small table the above chart is based on:

Work Remaining

The backlog started with about 170 user story points, and the team has completed all but about 60 of those. The marker points show how many points remain at the end of each sprint. I found this a little counter-intuitive at first: the line is only extended after the sprint is completed. This means that the number shown in Sprint 5 (~60) is actually reflects the work still in play for Sprint 6.

New Work

Unlike waterfall methods, the Agile approach allows - even encourages - change. This means that scope will be fluid throughout the project, with user stories being added and removed along the way. In the simple chart it is not possible to discern between the effect of completed stories and the adding/removing of stories. How much progress did the team make in Sprint 5? The chart shows a reduction of about 20 points, but if 10 points of new scope were added, then the team really completed 30 points. Simplicity comes at the expense of understanding team performance (velocity.) This chart shows the progress of the overall project more than that of the development team. Here is an example of a chart and its source table that includes new work:

Bugs

Bugs happen. Plan on it. So, do you include bug stories as added scope, or does the team velocity just take a hit? I'll write more on this later, but for now I'll just state that I do the latter. Bugs are recorded as stories, but I don't ever count their points. This means the burndown doesn't reflect all of the work the team is doing, but this shouldn't be a problem as long as the bug-related points are nominal and fairly consistent across the sprints.  Bottom line is that bugs are a drag on velocity - and that's probably the right way to think about them.

Budget

Budget is implied in the schedule. Typically, the budget is set at the outset of the project (another post, another day), and combined with the cost of the team over time, this determines the number of sprints. Don't forget that there may be other costs in the project than just user story development...

What's Not in the Chart

I only use the burndown chart for the "build" portion of the project. Planning work that precedes it may not involve the whole team, and will likely not consist of delivering user stories. Work following may involve user acceptance testing and other tasks, again not relating primarily to user stories. Velocity doesn't seem to have much bearing outside of the build phase, which is why I have only (so far) used the burndown for that portion of the project. I'd be interested in other thoughts on this.

Summary

The Simple Chart shows the least amount of necessary information and is easy to understand. This might work particularly well with stakeholders that assume a burndown chart is a song by Talking Heads. For more informative charts, you'll have to wait for the next post...