Predicting the Unpredictable

2. What Estimates Are

Managers and sponsors ask a project team for estimates all the time. Sometimes, managers use those estimates to plan which project to do first—which is a terrible idea. More on that later. Sometimes, managers use those estimates to predict a target date. Sometimes, managers use those estimates as a commitment.

None of those ways are the way we should use estimates.

Here is the problem with using estimates that way:

• Estimates expire.
• Estimates change.
• Estimates are guesses.

Yes, “guess” is the dictionary definition of estimate. The more you know about the domain, the requirements, and how the team works together, the more educated your guess will be. But it will still be a guess.

Because estimates are guesses, you can’t ...