Velocity Is a Capacity Measurement

I already said velocity is not acceleration back in ​Understand Velocity​. Velocity can be a measure of capacity once the team is stable and understands how to work together.

A team’s velocity (regardless of whether it uses points or story counts) will vary while it learns how to work together. (Many people think it takes somewhere between six and nine iterations for a team to learn how to work together.) A team’s velocity might vary under other circumstances, as well:

• The team is learning a new domain.
• The stories vary in size and may be quite large.
• The team changed the iteration duration.

There are two potential drawbacks to measuring velocity. I said that velocity is the rate of change. That’s what you deliver (features or story points) over time. If you change your iteration duration, you change the time, one of the inputs to the rate of change. If you use story points and you decrease or increase the size of the stories, you change one of the inputs to the rate of change. If you maintain the same iteration duration and use features instead of points, your velocity measurements will be more accurate.

Measure Cycle Time to Understand Capacity
	Many teams, especially those working in iterations, measure their velocity in story points to understand their capacity. Instead of points, consider measuring cycle time. When the team measures its cycle time—possibly different times for stories, fixes, and interruptions—the team has a better idea about its capacity. For me, points are too variable, especially in a team new to agile approaches.