What is the Mysterious Event 'Refinement'?

This is the article for Day 16 of the Mamezou Developer Site Advent Calendar 2024.

I'm Ishida from the Agile Group. This time, it's a topic about "Refinement."

Are you all doing refinement? Although the word appears in the Scrum Guide, it's not included among the Scrum events, and it's not very clearly described what it is. Personally, I think it's the most mysterious event for Scrum beginners.

This time, I would like to think about such "Refinement."

The word "refinement" itself is not a very familiar English word. So first, let's check what "refinement" means in an English-Japanese dictionary.

In the sense of "refinement" used in Scrum, perhaps "sophistication," "improvement," or "enhancement" of product backlog items would be appropriate.

Next, let's look at what is written in the Scrum Guide. As usual, let's look at the latest 2020 edition. It is written as one paragraph in the section of the product backlog.

Product Backlog items that can be Done by the Scrum Team within one Sprint are ready for selection in Sprint Planning. The Scrum Team usually acquires this degree of transparency through refinement activities. Refinement is the act of breaking down and further defining Product Backlog items into smaller, more precise items. This is an ongoing activity to add details such as descriptions, order, and size. Many attributes may vary with the domain of work.

Refinement is the activity of splitting, adding details, estimating, and reordering product backlog items as preparation before planning.
Also, in the section on Sprint Planning, there is the following description:

Developers select items from the Product Backlog to include in the current Sprint through discussions with the Product Owner. The Scrum Team may refine these items during this process, which increases understanding and confidence.

Because it says "may refine," you might think that refinement is an activity that you may or may not do in Scrum, but that's not the case. This "may" refers to "may refine during planning." Usually, refinement is carried out during the previous sprint (before planning) before starting development on that backlog.

By the way, this sentence is written as follows in the original English version:

Through discussion with the Product Owner, the Developers select items from the Product Backlog to include in the current Sprint. The Scrum Team may refine these items during this process, which increases understanding and confidence.

In English, it is written using the verb "refine" rather than the noun "refinement."

Therefore, I feel that translating the sentence as:

The Scrum Team may further refine the product backlog during Sprint Planning.

would be more fitting.

Also, in the previous text:

Product Backlog items are ready for selection during Sprint Planning.

As it says, refinement should be completed, and items should be ready by the time of planning.
Therefore, the expression "may refine during planning" is incorrect, and I think "refine" here means that through the conversation between developers and the Product Owner during planning, the already prepared backlog items are further refined.

In the Scrum Guide 2020, there is no mention beyond "Product Backlog items are ready for selection during Sprint Planning" about when during the sprint or how much time should be spent on it. This part is slightly mentioned in the 2017 version.

The Scrum Team decides how and when refinement is done. Refinement usually consumes no more than 10% of the Development Team's capacity.

It feels a bit like "decide when and how to do it as a team." Unlike planning or retrospectives, the timing is not explicitly determined. This is probably why refinement is not defined as a Scrum event.

As for the method of implementation, you will explore what works best for your Scrum team, such as doing it for 30 minutes every day, doing it in blocks of 2-3 hours on a set day, or doing it ad hoc when people are available.

The guideline for the amount of time spent is said to be 10% or less of the development team's capacity. Conversely, it can be said that it's acceptable to spend about 10% of your time on refinement rather than development.

You may want to increase the time used for development as much as possible, but in the end, properly conducting refinement will affect the ease and speed of development in the next sprints.

When we talk about writing details in the product backlog, the team needs to align on how much we should write before refinement is over (planning can start). This is where the "Definition of Ready" comes into play.

We discuss and decide as a team what state the product backlog should be in to start planning. By doing so, we prevent spending too much time on refinement doing things that should actually be done during development.

For example,

• The design has been decided
• All developers understand the acceptance criteria
• Estimates have been made
  and so on.

In the Scrum Guide, the term "Definition of Done" often appears, which is a criterion for completing product backlog items.
It would be good to consider "starting with the Definition of Ready and ending with the Definition of Done" as a set.

Refinement is not a Scrum event, cannot be called development work, is not specified when to do it, and I think it remains mysterious in many aspects for Scrum beginners.
However, to refine backlog items through refinement and to start development smoothly, let's work on refinement today as well.