Why Re-estimate User Stories? #scrum #agile #xp
On the SCRUM Development list two questions often pop up, I call them the why and when of re-estimating. There are few defined rules on re-estimating, yet estimating and re-estimating is an important part of backlog grooming. Which is why this is a recurring question in many SCRUM fora.
Why should we re-estimate user stories?
As time goes on ideas and opinions have the tendency to crystallize and become more clear in the mind’s eye. The same goes for User Stories in the backlog, our opinions on scope and complexity User Stories become more well defined. This may mean that a User Story needs to have its metrics re-evaluated and re-estimated.
- When something new is learned about the User Story
- When User Stories are merged stories or split up
- The relative sizes of the User Stories changed
- Uncertain about the complexity of the User Story
- The team believes the estimate for any future work needs to be re-discussed and/or re-estimated
When should we re-estimate user stories?
- If we re-estimate the stories, we it prior to the sprint, during a grooming session
- Check the estimates during sprint planning session
- Re-estimate any story that has not yet been accepted into a sprint
Conclusions
Read more articles on Agile, SCRUM or XP…
If we don’t re-estimate:
- The velocity will go through the roof when we implement those stories and the variations in velocity will be greater
- The release plan will be less realistic and the range of story points to release will vary widely
- We keep our estimates coherent with the past but less coherent for the future. New stories will be estimated as smaller even though relative sizes will be the same
If we re-estimate:
- We shall re-estimate all the workflow stories to keep them coherent
- The velocity will remain stable
- The release plan will be positively reviewed and allow us to take more in
- We make our estimates for the future more coherent if we add any new story
A discussion on Re-estimate User Stories for a More Accurate Velocity?
Sources: Stephan Huez, Roy Morien, Steve Ropa, Charles (chuckspublicprofile)
General Musing 
I agree. Estimates are approximations. As new information becomes available and knowledge improves, estimates will change. Some will increase and some will decrease (at least in theory).
Estimates should be revised before each sprint. If something is learned during a sprint that causes extra work, it may be wise to return the story to the backlog or split it up into multiple stories.
Vin D'Amico
August 19, 2011 at 4:04 pm
The Scrum book describes some extreme cases for issues such as this during Sprints, I’m of the opinion that User Stories which are not what they seem during the sprint are serious cause for the team to evaluate their efforts, as this makes it clear that there was no due diligence performed on the User Story. I have a story, which I’m saving for an upcoming blog, about a User Story which was badly evaluated by the team, despite warnings from PO, SM and myself, committed to in two consecutive sprints and was allowed to be come an impediment for a successful completion of the entire project.
webhat/redhat (@webhat)
August 19, 2011 at 6:31 pm
Car shopping is stressful. Now that there are hundreds of makes and models
to choose from, not to mention promotions and payment options, it’s easy to become frustrated and stressed out. The information here will help make buying a car as easy and stress-free as possible.
cars
June 1, 2013 at 2:12 pm
Hi there everybody, here every one is sharing these
kinds of know-how, so it’s good to read this webpage, and I used to pay a quick visit this blog daily.
unlock code blackberry q10
June 12, 2013 at 7:51 pm