Sunday, December 06, 2009

Getting the estimations "accurate" in one go – a vestige

A team adopting Agile method for the first time tends to do many mistakes during the initial days. One of the common mistakes is about trying to do accurate estimation. During the Iteration Planning Meeting(IPM) of the first iteration, the team does not know their velocity and tends to spend time trying to come up with “accurate” estimates or estimates with additional unscientific buffers. They tend to spend too much effort detailing out tasks and estimate them.

Agile methods discourages teams spending too much of effort on reaching perfection in one go, especially around estimations. It recommends teams to apply the empirical control model by frequently inspecting the estimations and adapting them.It recommends to go with daily re-estimation technique.

Daily re-estimation

Agile methods recommend that

  • During the IPM, estimation for the requirements should be done with whatever knowledge one has at that point of time
  • While doing the daily re-estimation try to steer and come up with more accurate estimates
  • Use the optimistic estimates rather than the pessimistic estimates

Subsequent Iterations

Right from the first iteration, the team must track couple of key parameters, For Ex:

  • Planned effort Vs actual effort
  • Number of committed stories Vs actual stories delivered
  • Number of new tasks discovered during the iteration
  • Planned resource budget Vs actual resource budget

Once the team gets to know their velocity, the future iterations could be estimated and planned in a better way.


  • Trying to detail out all tasks, trying to provide accurate estimations, detailed planning and analysis are the vestige coming from the waterfall model
  • Agile recommends frequent delivery of working software rather than wasting time on analysis-paralysis

1 comment:

Gareth J M Saunders said...

Thanks -- that's exactly the post I needed to read today, having just begun to use an Agile approach for the first time.