The goal of estimation is to create in a sustainable and repeatable fashion, an estimate of effort that is useful for iteration planning. Estimation is done at every level of planning and involves everyone involved in that planning session. Estimates reflect the team’s best guess at the moment. Early on, estimates may be +/- 100%. As learning grows, estimates become more accurate. Discussion of who is involved, what to do, how to do it, tools and techniques, expected outcomes, and references.

Resources related to estimation

Carry-Over Work (Article)
Estimation (Article)
How Can We Deliver the Most Value from Available Resources? (Blog Entry)
How Small Are Our Stories? (Article)
How to Use Estimates (Article)
If We Do Estimate, What Estimation Method Should We Use? (Article)
Should We Estimate Our Work? (Article)
Team Estimation (Article)
When, Why and How to Estimate (Article)