The Burndown chart is a type of graph used fundamentally in agile methodologies, especially in Scrum, to verify the status of the progress of a Sprint. It is characterized by allowing the visualization and analysis of the team's progress and knowing if it will be able to complete the pending work in the correct time and with the established budget.
The word "Burndown" summarizes the functionality of this type of graph since the pending tasks "burn" until they reach the lowest point of the axis.
We can say that a Burndown chart shows the amount of work that remains to be done (Y-axis) on a given day from when the work starts (X-axis) until it is completed.
Advantages of the Burndown chart.
- It gives cohesion to the work team: This diagram allows all team members to be aware of the past, present and future status of the Sprint since it is also intuitive and simple to understand.
- It generates a visual representation of the progress: The Burndown chart allows an overview of the project which is effective for jobs that have multiple changes and adaptations.
- It summarizes the data with simplicity: Its particularity lies in the fact that evolution can be seen in a simple way without falling into complexities, making it communicable for everyone.
Types of Burndown Chart.
Sprint Burndown chart
It is a graph that is constantly updated, and that consists of the number of hours or activities, expressed in story points, that remain to be completed versus the day of the Sprint. It is the simplest type and the most used.
Release Burndown chart
This type of chart takes a concept from the Scrum work: the release, which involves the delivery of a finished product.
Therefore, in this graph, the number of stories delivered correctly in each of the iterations or Sprints is taken.
If you want to deliver different functionalities in X time, this is the ideal graph to use, in addition to helping to know the status of the independent delivery of the Sprints that comprise it.
Product burndown chart
It is applied in closed projects, that is, those whose time and cost are determined in advance. In these cases, a more complete estimate is required to be useful. The chart is used to predict how many Sprints will be needed to complete the project.
As the scope, time and cost are defined, it allows knowing if the stipulated date will be reached.
Building a burndown chart.
Time: X axis
The X axis of the graph represents time. If it is a Sprint, x=0 will be the beginning of it, and the last value of the X axis must be the end of the Sprint.
In the case of a closed project, the time is limited by the commitment date established with the customer. On the other hand, if it is a delivery or relase, the time is its expected date. Time is subjective according to each project, but it must always have a beginning and an end.
Work Quantity: Y Axis
The amount of work is located on the Y axis of the graph, which must be fulfilled based on the time established on the X axis. The tasks must be estimated, in terms of stories, days or also in hours. In the case of the Scrum methodology, it is the iteration task list (Sprint Backlog).
The guide line is the diagonal line that joins the last value of the Y axis, that is, the maximum committed work, with the last value of the X axis, which corresponds to the maximum date for the committed work. This line serves as a reference to know if the tasks are carried out correctly, or if, on the contrary, there are delays in the task.
This line will be the one that will be updated as each task is executed with the estimated time it should be done. For each completed task, there will be an estimated ratio.
In agile methodologies, story points are used to estimate backlog. In a burndown chart, story points are plotted on the X and Y axes. For example, the Y axis can have 0 to 100 story points, which represent dedication, and the X axis can have 1 to 30 burndown story point, which represent the days remaining to finish the job. If the points are below the progress line it means that the project is being completed faster than estimated.
Goal of the sprintThe overall goal of the Sprint should be included in the chart. For example, form a straight line that represents 50% effort for 12 days. This enhances the progress of the tasks and pushes to continue achieving them.
Applying a Burndown chart is a useful tool to quickly visualize pending work and the time it takes to complete that work. However, a Burndown chart does not provide information about the trajectory of a project, such as the changes made. For these cases, the graph should be complemented with a product backlog and a change control process to track it accordingly.