A new agile coach asks the Scrum Master to add a two-hour "Backlog Refinement" event to the calendar every Sprint, and to publish its timebox and its mandatory attendee list alongside the other Scrum events. What is the accurate position?

Professional Scrum Master I, objective 1. Understanding and applying the Scrum framework medium

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The options

Correct Refinement is an ongoing activity rather than a Scrum event, so it has no defined timebox and no defined attendees — the Scrum Team decides how to do it

Correct. Scrum defines five events and refinement is not one of them. A team may well choose to hold a regular session, but that is the team's practice, not a rule of the framework.

Not correct Refinement is the sixth Scrum event and is timeboxed to ten per cent of the Sprint

Wrong on both halves. There are five events, and the ten per cent figure is a guideline from an older edition of the Scrum Guide that the current framework does not contain.

Not correct Refinement happens only during Sprint Planning, which is why no separate event exists

Wrong. The Scrum Team may refine items during Sprint Planning, but the Product Backlog is also refined as needed during the Sprint — refining is an ongoing activity, not a slot.

Not correct Refinement is the Product Owner's private preparation and the Developers should not spend Sprint time on it

Wrong. Sizing belongs to the Developers, and items usually acquire enough transparency to be selected precisely through refining activities the Scrum Team does together.

Why

Refinement is the act of breaking down and further defining Product Backlog items into smaller, more precise ones, adding detail such as description, order and size, and the attributes involved vary with the domain of work. Its purpose is a specific kind of readiness: items that the Scrum Team can Done within one Sprint are deemed ready for selection at Sprint Planning. How a team gets items to that state is entirely up to it.

Where this comes from

Cited
Scrum Guide section Product Backlog
What it says
Product Backlog refinement is the act of breaking down and further defining Product Backlog items into smaller more precise items.

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