Product Backlog Refinement
Summary: Split big items, analyze items, re-estimate, and re-prioritize, for future Sprints.
Participants: Team; Product Owner will attend the entire activity if they are the expert who can help with the detailed refinement, otherwise they may attend only a subset to set direction or re-prioritize; others who understand the requirements and can help the Team; ScrumMaster will attend during initial sessions to coach the group to be effective, otherwise may not attend.
Duration: Usually, no more than 10% of the capacity of the Team for the Sprint, though it may be longer for “analysis heavy” items. For example, in a two-week Sprint, perhaps one day is spent on refinement.
One of the lesser known, but valuable, guidelines in Scrum is that some percentage of each Sprint should be dedicated by the whole Team to refining (or “grooming”) the Product Backlog to support future Sprints. This includes detailed requirements analysis, splitting large items into smaller ones, estimation of new items, and re-estimation of existing items. Scrum is silent on how this work is done, but a frequently used technique is a focused workshop near the middle or end of the Sprint, so that the Team and Product Owner and other stakeholders can dedicate themselves to this work without interruption.
This refinement activity is not for items selected for the current Sprint; it is for items for the future, most likely in the next one or two Sprints. With this practice, Sprint Planning becomes relatively simple because the Product Owner and Scrum Team start the planning with a clear, well-analyzed and carefully estimated set of items. A sign that this refinement workshop is not being done (or not being done well) is that Sprint Planning involves significant questions, discovery, or confusion and feels incomplete; planning work then often spills over into the Sprint itself, which is typically not desirable.