We’ve adopted a point based estimating system as part of rolling out XP, with 1 point being simple, 2 moderate, 3 difficult and 5 meaning too hard to estimate (either too big or too technically difficult). One large feature for the next release has been plagued with 5 ratings, both because the feature is big and hard to break down and because it’s technically very difficult so we’re not always sure parts are possible, let alone how long they’ll take.

Today we reached a major milestone – we laid out all the critical stories that have to be done to make this bare minimum of the feature complete and managed to assign estimates to them that weren’t just a bunch of 5s. Even better, a lot of them were given 0 ratings (too small to be a one but a number of 0s adds up to a 1) because we can leverage work we’ve already done. I think we wound up with about 34 points of work to do (once the 0s were grouped together into 1s).

The new problem is that we don’t know what our velocity is. Velocity is deceptively difficult to work out because unless your estimates are consistent your velocity is worthless and we’re just starting to get used to estimating this way. It’s made worse by the fact that there are so many other projects that go on in our engineering team and thus change our velocity from week to week, but we’re making progress in managing it all better and working out how long it will all take.

Regardless, it’s really good to know that the feature is technically possible, will be quicker to complete than we initially thought and we have some idea of how much longer it will take – about 34 points worth to get the basics.