Another tool that many agile PMs use to track progress is the "burn-down chart," illustrated in Exhibit 2. The PM starts at the upper left of the chart, before any development work is completed, and as features are completed or "burned down," the PM tracks that progress with a simple line chart. In this example, the PM is tracking a release, which contains a total of 200 features, or story points, that the team must "burn through." A burn-down chart also can track the progress of an iteration by substituting "days" for "iterations" on the y-axis. As features are built and tested, the number of story points remaining is plotted and a line connecting each point is drawn. By keeping the burn-down chart current, PMs can offer their customers a quick, visual representation of the functionality that has been delivered and is left to be delivered, and provide clues regarding the team's productivity.
If the chart is a flat line and not moving down toward the zero point at the lower right, it shows that the team is stuck, not able to make progress as expected. It sends a signal to the PM that a technical issue, an organisational barrier or a teammate's productivity requires attention. If the plot moves upward, it indicates that new features have been added to the backlog or features previously considered complete have moved back to development. In agile development, a new feature added to an iteration can mean many things. It can be a positive sign of fruitful interaction with the customer, or it can be the first indication of scope creep or project gold-plating (in which team members add features because they are "cool" or "elegant").
If an upward tick in the burn-down chart signifies that a feature previously considered complete has moved back into the unfinished column, this is a negative indicator. Features should only be burned down on the chart if they are developed and tested and ready to be integrated into the iteration or release. Counting unfinished features creates all sorts of complications, from damaging internal team trust to corrupting the entire burn-down process. PMs should set clear rules regarding the state of comple¬tion required before a feature, or story point, is counted as burned down.