According to Roman Pichlers "Agile Product Management with Scrum"
"[...] we prepare just enough [backlog] items for the upcoming sprint, just in time."
IMHO this includes, among other things, estimating the story points of the respective backlog items.
At the same time "[the release burndown] is based on the following two factors: the remaining effort in the product backlog, and time."
IMHO this two statements are contradictory because we don't know the story points of all backlog items at the beginning or during a sprint.
Please can somebody help me with this?
Thank you in advance
Andi
A story must be expressed as story points before it's taken into sprint, these points are summed up to see when you planned enough for one sprint. You also need to points in order to maintain a velocity going from sprint to sprint.
It's fine to do some rough pre-estimating of backlog items though. This helps the product owner do some release planning and prioritizing ahead of a spring planning meeting. It also helps creating a release burn down chart (in combination with the team's velocity). The rough estimates may be re-estimated during a sprint planning meeting where there are usually discussed in full detail.