DEV Community

Discussion on: Why Estimation Is Always a Guess

Collapse
 
eljayadobe profile image
Eljay-Adobe

Love it!

Mike Cohn's excellent book Succeeding with Agile, chapter 15 Planning has a section called Separate Estimating from Committing.

I think it is important to emphasize that an estimate is not a commitment. I would only be willing to give an estimate as an iron-clad commitment if I am allowed to give the estimate after the work is done. ;-)

For those teams that use story points and calculate velocity as story points per sprint, the theory is that velocity is a better way to estimate how long it will take to get how much work done (with some range and confidence); or vice versa, given a target date, how much work is expected to be done at a minimum, and how much work may possibly be done as a maximum, and what work will not be done.

Using historical data ("yesterday's weather") as a predictor is a good thing, in conjunction with short iterations and an empirical approach. Works much better than wishful thinking, gut feel, and hand-waving that I've seen with Gantt charts laid out at the start of a project by a project manager who was unable to account for every sickness, mistake, requirement change, or surprise work discovered during development. (Gantt charts that are written in pencil, fluid, continuously adjusted & updated, as a map-and-a-plan to get from here-to-there are okay. Gantt charts that carved in stone, are immutable, drives the goals and milestones, and slippages are blamed on others are not good.)