Affinity Estimation

Purpose

Affinity Estimation lets a team size 20–100+ Backlog items in under 30 minutes by leveraging silent sorting and group comparison rather than item-by-item discussion. It is ideal for initial sizing of a new backlog or portfolio.

At a glance

How to run

1. Setup (3 min) — Write each Backlog item on a card. Create columns for each size bucket (1, 2, 3, 5, 8, 13, 21 or XS–XL).
2. Seed the wall (2 min) — The facilitator places one well-understood item in a middle bucket as a reference.
3. Silent sorting (10 min) — Team members take turns (or work simultaneously) placing cards into buckets. Anyone can move any card silently — no talking allowed.
4. Discussion pass (10 min) — Walk through the buckets. Anyone who disagrees with a placement speaks up. Allow 1 minute of discussion per disputed item, then majority rules.
5. Record (5 min) — Capture the bucket assignment for each item.

Materials needed

• One card per Backlog item
• Size-bucket labels on a wall, table, or digital board
• One reference story placed in advance

Pitfalls & common mistakes

• Talking during silent phase — Enforce silence strictly; discussion in the sorting phase causes anchoring.
• Too few buckets — Use at least 5 to provide meaningful differentiation.
• Arguing endlessly on edge cases — If a card sits between two buckets, pick the larger and move on.
• Not using a reference story — Without calibration the first items placed set an arbitrary anchor.

Inclusion & accessibility

• Use large-font cards so everyone can read from a distance.
• Ensure the wall is at a reachable height for all participants.
• For remote sessions, use a digital board where everyone has edit access and place items via drag-and-drop.

Variations

• Magic estimation — Same concept but only the facilitator handles cards while team members call out movements.
• Bucket estimation — Items are placed into buckets without predefined scales; the team assigns numbers after.
• Two-pass estimation — First pass is completely silent; second pass allows brief verbal corrections.

When NOT to use this

• When you have fewer than 15 items — card-based estimation is more precise.
• When items require detailed discussion to be understood — run Backlog Refinement first.

Source & further reading

• Cohn, M. (2005). *Agile Estimating and Planning*. Prentice Hall.
• Loeffler, M. (2017). *Improving Agile Retrospectives*. Addison-Wesley.