Are There Limits to Software Estimation?

Charles Connell submitted this analysis on software estimation, a topic which keeps coming up because it affects so many many programmers. Read this post about J.P. Lewis's earlier piece as well, if you'd like more background information.

Comments

Re:Accuracy, and doubling a double

[jpbelang]

The danger with constantly doubling is that it leads to falsely large numbers for small projects.
A project estimated at one day should NEVER take four days. A project estimated at three months could take a year.

In my opinion, everything is about risk and you seem to agree (the reasons you double your time is generally for unforseen events).

So if risk is the problem, we have to reduce risk. How should this be done ? The simple solution is shortening your horizon.

Instead of saying "this project of size X will be delivered in three months", deliver smaller increments more often ("this project of size X/12 will be delivered in one week")

This is extreme planning.

So I'm an XP evangelist. sue me :)