06 September 2017 by Scott M. Graffius - filed inMetrics - Agile
Velocity is a simple but powerful method for measuring the rate at which Scrum teams deliver business value. To calculate velocity, simply add up the estimates (usually in story points) of the features, user stories, requirements or other backlog items completed in an iteration. Only work completed per the definition of done counts.
Actual velocity is the sum of the team’s delivery of completed work during an iteration, usually measured in story points.
Example 1: A team completed work on three out of three stories in a sprint:
• Completed story “A” had 3 points
• Completed story “B” had 5 points
• Completed story “C” had 8 points
The sum of the three completed stories is 16, so the velocity is 16.
Example 2: A team completed work on two out of three stories in a sprint:
• Completed story “X” had 2 points
• Completed story “Y” had 5 points
• Incomplete story “Z” had 5 points
Only completed stories count. The sum of the two completed stories is 7, so the velocity is 7.
Velocity values may fluctuate from iteration to iteration, but the values often stabilize for teams after they’ve completed between three and six sprints.
Planned velocity is the historical velocity for the team. It is sometimes called the estimated velocity or ideal velocity. If the team has not done any iterations before, there is no historical data, and planned velocity does not yet apply. If there is historical data, sum all the velocity values and divide by the number of iterations to obtain the mean average, and use that value as the planned velocity. Using a simple method like the preceding one is advised, especially when starting out with Agile Scrum. Some organizations use alternatives—such as a three-point moving average, trimmed mean average or the median average—for planned velocity.
This content is an abridged excerpt from the award-winning book, Agile Scrum: Your Quick Start Guide with Step-by-Step Instructions, available in paperback and ebook formats at Amazon. For more on the book, please see agilescrumguide.com.