Affinity Sizing: Efficiently Sizing a Product Backlog

Affinity Sizing: Efficiently Sizing a Product Backlog

By: Giovanna Berry, CSP, PMP, MBA


One of the more overwhelming activities that need completing in Scrum projects is sizing the entire backlog or a larger quantity of user stories. To make this exercise less cumbersome and even a bit fun, try the affinity sizing method in a collaborative team session. We’ve had great success using this method to size large backlogs efficiently, in a way that keeps the entire team engaged.

Let’s jump right in. For this method to be effective, properly prepare by making sure the appropriate prerequisites are in place before pulling the team together for a session.

When to use Affinity Sizing

  • There are more than 20 story cards that must be adequately sized
  • Starting a project and need to get an entire product backlog sized
  • Recalibrating your team’s relative sizing scale

What to do before the session:

Materials needed

  • All story cards that are needing to be sized or resized for recalibration printed or written on index cards, sticky notes
  • A large enough open wall space that will fit all of the story cards
  • A room or area large enough to effectively hold the team you are working with
  • Additional sticky notes and Sharpies to write the affinity scale (xs, s, m, l, etc.)
  • Optional – healthy snacks to keep up the energy level

Skill sets and attendees

  • Scrum Master – This individual is the ideal facilitator of this session
  • Team members – The team members that will be building, testing, and deploying the functionality represented in the story cards
  • Product Owner – This team member will have the insights for the required functionality to clarify and answer any questions the team has
  • Agile coach – If your team is new to Agile practices, or you have the benefit of access to an Agile Coach, it is highly encouraged to request support in this session

Know the team’s Sprint length

Plan the timing of the session

  • This is more variable depending on the number of story cards being sized
  • § For reference, I’ve facilitated through the following:
    · 40 Story Cards in less than an hour
    · 100 Story Cards in an hour and a half

The session

Set up

Place sticky notes representing the affinity sizing scale horizontally across the top of the wall that will be your working canvas.

It’s recommended to use extra-small (XS) as your smallest possible unit of measurement up to extra-extra-large (XXL). Anything on the XS end of the spectrum should reflect that absolute smallest, most straightforward piece of work that you could encounter in your backlog. Anything on the XXL end of the spectrum should be the most sophisticated/highest effort story cards the team could face.

Place a large post-it note or heading on the wall with the word “Parking Lot” for the team to place any story cards that are too unclear or nebulous to size.

Affix all of the story cards to be sized to the wall in an area together.

Initial affinity sizing

Explain the mechanics of the session (to be explained to you in this article).

Open the floor to have the team members come up to the story cards needing sizing on the wall.

They should pick a story card to review, and silently place it beneath the size they feel it most closely aligns to, based on the complexity, effort, and unknowns/risks to implement the feature.

Once all of the story cards are placed up beneath the affinity sizing scale, move on to the next part.

Refining and level-setting on the size as a team

Now that all of the story cards have been initially sized, give the team 15-30 minutes to review how the story cards were sized and allow them to move them around on the sizing spectrum if they disagree.

This should still be done silently; it provides the team an opportunity to review and refine before coming together to discuss.

Once the timebox has run out, come back together as a group. The Scrum Master/facilitator will walk through each story card, reading the available information on it, and announce where its affinity sizing.

The team will have an opportunity, at this point, to vocalize whether they are in agreement with the size or ask any questions of the PO to refine the size. Facilitate discussion until the team agrees on the size for the story card.

Repeat the process for each story card.

Don’t forget to address any story cards that end up in the Parking Lot, as well. Discuss these as a group to size.

At the end of the session, you will have a sized backlog or subset of a backlog accomplished relatively efficiently.

Why you should use the Affinity Sizing method

While the impacts of leveraging this technique may seem tactical, they can be far-reaching to an organization, project, and team. For a financial institution, it allowed their small development team to size a large backlog of technical debt items efficiently. This, in turn, let their leadership team gain insights into the scale of the effort and quantify ROI. Experienced Agile development teams have been able to hit the ground running out of Sprint 0 with a full-sized backlog that didn’t require a significant effort of time to size. There are many benefits, with the most commonly realized being early visibility into the scale of effort/work and time savings.

In closing

Introducing this method to your team for a large-scale sizing effort will allow you to keep everyone engaged and complete an often arduous exercise in a fun way. Some groups have enjoyed this method so much that they maintained physical sizing walls for their ongoing sizing efforts. Try this method out when an opportunity arises and drop us a line with your thoughts!


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