On the topic of velocity of Agile teams

Velocity isn't actually part of Agile or Scrum. It is just a tool sometimes used by Agile and/or Scrum teams in addition to many others -- like throughput -- that are useful for measuring progress and for forecasting performance.

So here is an example of why it is useful to know the velocity of an Agile and/or Scrum team from another article.

As an example, the velocity of a projectile issued from a cartridge in a firearm is unknown until actually fired and the speed measured. It is useful to know the "forecasted" or "projected" velocity of a particular cartridge in shooting sports prior to expending the cartridge. Especially at long range. The forecast for a given cartridge recipe, or average velocity, is accomplished by collecting data from test firings of many cartridges in standardized tests. Manufacturers publish the average velocity so that users may forecast performance of the cartridge. If you purchase a box of cartridges and measure the actual velocity / performance of say, 20 cartridges, you will find that the velocity changes for each round (especially in lower quality ammunition). Even when fired from exactly the same firearm. Variables such as weather, geography, arc/gravity, powder chemistry and amount, and the physics of the cartridge, projectile, barrel and action affect the outcome. So there are really two versions of velocity in this example - forecasted or average and actual. Actual velocity of each data point individually is of no value. A sufficient sample size must be observed to determine a predictable velocity used for forecasting performance of the cartridge under normal use.

The same logic applies to teams using velocity.

Read the related of the articles at blogagility.com.