Estimates need to reflect reality. Some basic characteristics of what we need from estimates include:

• The estimates consistently reflect the capacity of the Team to deliver.
• The estimates consistently reflect the size of the work no matter what kind of work it is. For example, it should not matter that we are estimating a new feature or defects
• They are truly relative in that on a Team by Team basis an 8 is an 8 and an 8 is about 4 times a 2 no matter the source.
• We provide data that allows the use of ranges of estimates to help understand the risk profile of the work. For example, at the release level, the Product Owner should be able to use best, average and worst velocities to understand what is likely to happen.