Visible progress
A team must keep its progress visible at all times. It will create many additional artifacts in order to ensure visibility. Some common visibility tools are the release and sprint burndown charts.
Release backlog and burndown
A subset of the product backlog that has been identified for a particular release is called the release backlog. Even though release backlog can be defined up front, the product owner may remove items, exchange items, or negotiate scope depth for some items as he/she considers scope, time, and cost throughout the duration of the project. Therefore, the release backlog should be updated throughout the project. Chapter 2, Release Planning – Tuning Product Development, provides more detailed information about product backlogs, release burndowns, and backlogs.
The release burndown chart displays how much work remains in the release backlog at the end of each sprint. This provides the product owner with important information so that he/she may make well-informed decisions about scope, cost, and time. In the following diagram, you can see that the amount of work remaining at the end of each sprint is more than the work planned:
Sprint burndown
During a particular sprint, if everyone on the team updates the sprint backlog with the number of remaining hours per task every day, then the team can see if they will be able to burn down the number of task hours by the end of the sprint. In the following figure, you can see that the team did not complete all the tasks it had identified in sprint planning; approximately 50 hours remain.
This burndown concept is very important because, once set, the sprint end date does not change. Coupled with a daily Scrum, the sprint backlog and burn down chart can help teams visualize when they might be getting off track and turn the conversation to focus on what to do about a given situation. The sprint burndown "burns down" hours over days of the sprint, while the release burndown looks at units of work (often referred to as points) for a release, or number of sprints. Chapter 3, Sprint Planning – Fine-Tune the Sprint Commitment and Chapter 5, The End? Improving Product and Process One Bite at a Time, provide more details about burndowns and backlogs.