Because requirements in Scrum are only loosely defined, they need to revisited and clearly defined before they come into the Sprint. This is done during the current sprint in a activity called Product Backlog Refinement.
Duration of the PB Refinement
The guidelines in Scrum is to usually spend 10% of the Development Team effort in Product Backlog Refinement. This activity is optional in Scrum. Hence, when/how/how-much is a decision which is left to the Development Team and Product Owner.
What gets done?
Product Backlog Refinement is not for PBIs selected for the current Sprint; it is for items in future Sprints. A good practice is to have at least two Sprints worth of work ready to go in the Product Backlog. Sprint Planning becomes relatively simple because the Product Owner and Scrum Team start the planning with a clear, well analyzed and estimated set of stories. If refining the Backlog is not being done (or not being done well) Sprint Planning will involve a significant amount of questions, discovery and or confusion. Following are some of the activities done during Product Backlog Refinement
- Clarifying Product Backlog Items (PBIs)
- Splitting larger Product Backlog Items into smaller ones
- Reordering of the Product Backlog Items
- Adding Acceptance Criteria to the PBIs
- Identifying dependencies
What is Product Backlog Grooming?
Product Backlog Grooming and Product Backlog Refinement is an synonym – that means it is the same. The word “Grooming” has negative meaning in some parts of the world and hence the word “Grooming” has been replaced with the word “Refinement”.