During which of the following Agile Team events do team members estimate relative story sizes?

Backlog Refinement is the Agile Team event where team members estimate relative story sizes. Backlog Refinement is an ongoing process where the team collaborates with the Product Owner and other stakeholders to review, split, prioritize, and estimate the stories in the Team Backlog1 One of the main objectives of Backlog Refinement is to ensure that the stories are ready for Iteration Planning, which means they are clear, feasible, testable, and small enough to be completed in a single iteration2 To achieve this, the team uses relative story sizing, which is a technique to compare the effort, complexity, and uncertainty of different stories based on a common reference point3 Relative story sizing helps the team to create a consistent and shared understanding of the scope and value of the work, as well as to optimize the flow and predictability of the delivery process4 The team can use various methods to estimate relative story sizes, such as story points, T-shirt sizes, or Fibonacci numbers35