James Shore is currently working on his book – The Art of Agile Development. For a while now Shore has been posting up pre-publication review chapters from this upcoming book. The latest section up for review covers the topic of Estimation, and its well worth reading.
This chapter really resonates with me since parts of it pretty much describe the approach to estimation we follow in our development group at Talis. We estimate how much effort it would take to complete indiviual stories. Our iterations last a week. At the beginning of each week we total up our velocity for the previous week, for example 16, and then select 16 units worth of work for the coming iteration. If we repeatedly hit our target over the course of a couple of iterations then as a group we might pick more than our velocity for the following iteration. All the members of the development team take participate in the estimation, this ensures that everyone is “bought-into” the plan. This approach leads to better communication and can help clarify requirements it also engenders greater trust within the team.