Actual vs Estimated

In Agile, there’s a never ending debate between the “Keep track of your estimates, compare them to actuals, use the deviaiton to improve your future estimates” family and the “DON’T track actuals” family.

I’m feel much more in the “don’t do it” family, however, as a coach or Scrum Master, my approach is :

“Do what you feel is the right thing. If you choose to keep track of the actual vs original estimates, do it well. If after a few iterations, I realize that you don’t use this data to improve the estimates, I’ll remind you to at least try. Then you’ll tell me if this improved anything and is worth the time spent.”

60% of the teams decide not to track the actuals, 20% don’t track the actuals in a usable way, 19% don’t use actuals during the planning meeting, 1% find it useful.

What is your experience ?