- Velocity measures how much functionality a team delivers in an iteration, a.k.a. a sprint.
- Velocity measures a team’s ability to turns ideas into new functionality in a sprint.
In Scrum, Velocity is most often arrived at through a “Delphi EstimationTechnique” known as “Planning Poker”, which uses Story Points. Delphi estimation is technique where subject matter experts anonymously give their estimates in integer value, using the Fibonacci sequence, for consideration, discussion, and debate. The Fibonacci sequence is as follows: 1, 2, 3, 5, 8, 13, 21, 34, 55, and so on.
Lets take a closer look:
Analogous Estimating & Story Points
Story Points are unit-less, arbitrary numbers that predict productivity (a.k.a. velocity) and are a valuable only to the team who created them! A team, for example, might collectively decide that driving a metal line post into the ground for a chainlink fence is a 3. All other work associated with installing a fence is “sized” relative to the line post reference story that was given a 3. So, for example, digging a hole and setting a corder post in cement is an 8, and removing a rock that was impeding the installation of the line post might be sized as a 21.
This is a much better approach to estimation than “man hours” or “ideal days” because “ideal days” are misleading in that they really have nothing to do with getting work done. Further, people assume ideal days among various individuals can be added together when we intuitively know this is not true. A young, healthy, 6′ 4″ football player is likely to take much less time to drive a metal post into the ground than a middle-aged, sedentary, 5′ 9″ chess player.
Ideal Time can NOT be used to measure work because the underlying assumption is that you are working without any interruptions and everything you need is readily available. (Never going to happen!)
• Idea time for a football game is 60 minutes, but the elapsed time is 3+ hours
Shortcomings of sizing with Ideal Time
- My ideal days can’t be added to your ideal days, they are different (not fungible).
- Ideal days do not represent duration and are, therefore, confusing and misleading
- Traditional Project Management uses “Ideal Days”