Affinity mapping: turn forty ideas into five themes before you vote
Run this method in IdeaHone
Creates a space with the entities and scoring criteria of this method, ready for your next session.
A good brainstorm ends with forty notes on the wall, and at least a third of them say nearly the same thing. "Refill van", "mobile refill", "refill truck at the market". Vote on that list and the votes split across the duplicates: the idea the room likes most loses to one that happened to be written only once. Affinity mapping fixes this before the vote. The group sorts the ideas into clusters of things that belong together, names each cluster, and then decides on the themes. Jiro Kawakita developed the method in Japan in the 1960s to make sense of field notes, which is why it is also called the KJ method.
Why sort alone first
The classic way is to stand at the wall together and move notes around. It works, but the first person to start sorting sets the categories, and the rest follow. Sorting alone first, then comparing, shows where the group actually agrees. Two ideas that most people put together belong together. Two ideas that only one person grouped are a matter of opinion, and stay apart until someone makes the case.
Running an affinity mapping in 30 minutes
- Gather the ideas in one place. All ideas from the session, one per note, written so that someone who was not there understands them. Fix unclear notes now, not later.
- Sort alone for ten minutes. Each person puts every idea into a group of their own, or leaves it on its own. No talking, no names for the groups yet.
- Compare the groups. Ideas that more than half of the people put together form a proposed theme. Ideas nobody agrees on stay loose.
- Name each theme in one line. Not a label like "Logistics" but a sentence that says what the ideas have in common: "Bring the refill to where people already are". If the line will not come, the group probably holds two themes.
- Merge duplicates as you go. When two notes say the same thing, keep the clearer one. Its supporters are not lost: they count for the kept note.
- Place the loose ideas. Some fit a theme after all, some form a small theme of their own, some stay alone. A strong idea on its own is fine; do not force it into a theme to tidy up the wall.
- Vote on the themes. With five themes instead of forty notes, a dot vote or an impact and effort matrix gives a clear answer.
Five to nine themes is a good result for forty ideas. Two themes means the groups are too broad to decide anything; fifteen means the sorting stopped too early.
Where affinity mapping goes wrong
- Categories before ideas. Starting with boxes like "Marketing, Product, Operations" sorts by department, not by meaning. Let the groups come out of the ideas.
- Theme names that say nothing. "Customer topics" could hold anything. A theme name is a short statement, and it should be possible to disagree with it.
- The facilitator sorts. If one person does the sorting, the result is that person's view of the room. Everyone sorts, the overlap decides.
- Losing the ideas inside the themes. A theme is a group, not a replacement. Keep the ideas under it, so the best wording and the details are still there when the theme is picked.
Score and prioritise ideas with your team
IdeaHone scores ideas against your criteria, shows them on a matrix and keeps the reasons, so the decision is clear and traceable.
What is affinity mapping?
A way to group many ideas or observations by what they have in common. People sort the items into clusters, the clusters get a name that states the shared meaning, and the group then works with the themes instead of the single items. It is also called an affinity diagram or the KJ method.
What is the KJ method?
The original form of affinity mapping, developed by the Japanese anthropologist Jiro Kawakita in the 1960s to organise field notes. KJ stands for his initials.
How many people should sort?
Everyone who will vote on the result. With fewer than three people, the overlap tells you little; with more than twelve, split into groups that each sort the same ideas and compare.
What comes after affinity mapping?
A decision on the themes: a dot vote, an impact and effort matrix or weighted scoring. The themes are short enough to compare, and the ideas inside them keep the details.
