Refinement is the act of breaking down and further defining Product Backlog items
into smaller, more precise ones. It runs continuously through the Sprint rather
than at a fixed point.
Not an event
Scrum defines five events, being the Sprint, Sprint Planning, the Daily Scrum, the Sprint Review and the Sprint Retrospective. Refinement is not among them, has no
timebox in the Guide, and no prescribed format. Teams commonly schedule sessions
for it, which is a practice rather than a rule.
What gets added
Detail such as a description, order and size. Attributes vary with the domain of
work. The aim is that items reach the point where the Scrum Team can complete
them within one Sprint, at which point they are deemed ready for selection in
Sprint Planning.
Who sizes
The Developers who will do the work are responsible for sizing. The Product Owner
may influence them by helping them understand and select trade-offs, which is a
different thing from setting the number.
Where it happens
Refinement usually consumes a portion of each Sprint, alongside the Sprint's
work. How much is left to the Scrum Team; the Guide does not prescribe a
percentage.
Common misconceptions
“Refinement is a fifth Scrum event with its own timebox.”
Scrum defines five events: the Sprint and the four within it. Refinement is an ongoing activity, not an event, and the Guide sets no timebox for it.
“The Product Owner sizes Product Backlog items.”
The Developers who will do the work are responsible for sizing. The Product Owner may influence them by helping them understand and select trade-offs.
“The whole Product Backlog should be refined to the same level of detail.”
Items are refined as they approach selection. Items that can be Done within one Sprint are deemed ready; those further down remain coarser.
2 questions test this concept
A team asks how much time to allocate to Product Backlog refinement and when it should be scheduled. What does the framework say?
ARefinement is a Scrum event with a timebox of four hours per month.
BRefinement is an ongoing activity rather than an event. Scrum prescribes no timebox and no schedule, and the Scrum Team decides how and when it happens.
CRefinement must take place immediately before Sprint Planning.
DRefinement is the Product Owner's individual responsibility and does not involve the Developers.
Backlog refinement agenda, A ninety-minute structure covering the current Product Goal, what changed since the last session, and the items nearest the top that are not yet ready for selection.