Iteration Velocity
This guideline describes how to calculate team velocity and use this metric to measure the team's capability
Main Description

Overview

The iteration velocity is used for measuring the capability of the team. This help in identifying the trend of how much work a team can complete in iteration.  Velocity can be meausred as in term of points, ideal days, days, hours, or any unit your team is using.

Velocity will typically fluctuate within the first couple iterations. If velocity fluctuates for more than one or two iterations, the team may need to re-estimate and/or renegotiate the release plan. Generally, velocity stabilizes between 3 and 6 iterations

To plan future iterations, use the proven history of the team to determine how much the team can do. Therefore, velocity is the right measure to use for planning future iterations.

Measurement Method

Velocity =  Number of unit of work the team has completed in a given iteration.

Unit can be points*, ideal days, days, hours or any unit your team is using for estimation.

* Points are units of relative size used in estimating tasks.

Measurement Analysis

A good way to monitor iteration velocity over time is to use the trend line. Ideally, the iteration velocity should accelerate over the time with iterations as shows in graph below.

The following picture shows the velocity trend in unit of points. The number of points is plotted in Y-axis and iterations are at X-axis. In initial iterations, the team Velocity is little low, then it is increasing and stabilizing as proceed towards middle iterations. In last iteration it is going down due to transition. If points are going up or down drastically in middle iterations, it needs the immediate attention.

  Iteration Velocity Metric

The following are some recommended tips. [COH04]

  • When determining velocity count only closed work item. Do not count work items that the team partially completed during the iteration.
  • A good way to monitor team velocity is to graph team velocity during the whole iteration and for every iteration.
  • Don't try to predict trends in velocity after only one or two iterations.
  • The number of actual hours spent completing a task or a story have no bearing on velocity.
  • Post big, visible charts in common areas where everyone can see them.
  • A cumulative chart is useful because it shows the total number of work completed through the end of each iteration.