Crowdsourced Idea Convergence

Affinity Diagrams

Affinity Diagrams are used to categorize and organize a large number of ideas into groups or clusters. The technique facilitates complexity reduction and enhances creativity.

Also known as KJ-Method (after its creator Jiro Kawakita), Affinity Diagrams are useful for clustering ideas and to discover patterns or relationships between them. This allows to group similar ideas together, eliminate duplicates and to find the best ones out of a large pile of ideas. After a brainstorming session, each available idea is written onto a post-it note. Then you start creating groups of ideas that belong together and attach them to a wall, blackboard or any other large surface. For ideas that don't fit into an existing group, you create a new one. After all ideas are grouped, you can then name the groups or clusters, draw connections and rank them by importance. Finally, the most promising clusters should be transitioned into practice.

What? In the 1950s, Jiro Kawakita developed the Affinity Diagram method. Known also as KJ-Method, Affinity Diagrams are a generalized brainstorming technique for gathering qualitative data [1]. The users can gather ideas, opinions or issues and discovering patterns or relationships between them [2].

Why? The technique is useful for getting people working on a creative level to solve issues and reach agreements. Selecting the best idea among many good, is a challenging process. The evaluation can vary according to the level of expertise, the degree of shared understanding, the personal biases of the evaluators or the amount of similar ideas. Affinity diagrams can facilitate the selection by allowing evaluators to organize the ideas in similar categories and reduce the level of confusion. With this technique, the evaluators can group similar ideas together, eliminate duplicates and identify the finalists. The technique is particularly useful for dealing with large volumes of data or for encouraging new patterns of thinking [2].

How? First, the goal of the session is clearly described. In the case of idea selection, the evaluators should have a clear understanding with regards to the required outcome. Second, each idea is written in a sticky note or index card. Third, the evaluators hang the ideas to the wall and silently start sorting the ideas into categories. For ideas that don't fit into an existing category, the evaluators create a new one. Fourth, as soon as all ideas are clustered, the evaluators label each group of ideas, draw connections and rank them by importance. Fifth, the most promising categories can be transitioned into practice [3].

In the figure below you can see a visualisation of the categorization process with the use of the Affinity Diagrams. Unlike the Innovation Funnel with the predetermined phases, the categorization process can be expanded into many more iterative phases, depending on the task requirements. In this example, you can see three consecutive phases starting with a large amount of ideas. By using Affinity Diagrams or one of the context-specific techniques such as the Four Categories method or the Bingo selection, the users can cluster the ideas into categories. These categories can be further refined through merging or discarding inadequate ideas.
Let’s assume that during an idea contest or a brainstorming session a number of fictional ideas emerges (phase 1). These ideas can first be clustered in various categories (phase 2). In the next step, the similar categories can be merged or inadequate categories can be discarded (phase 3). Finally, the remaining categories can be further pursued. The Affinity Diagram method is suitable for the shortlisting phase of the Innovation Funnel, as it does not cover the filtering or the winner determination phase.

The affinity diagrams concept is only one option for idea categorization. Similar concepts are the "Four Categories" method, the "Bingo Selection" method or any other alteration that suits the selection requirements.

Below, you can interact with some empty Affinity Diagrams.

You can:

Bingo Selection

The Bingo Selection is designed to help preserve innovation potential [4].

What?Similar to the four categories, the bingo selection offers predefined categories for clustering the ideas. However the technique targets the selection of the most prominent prototypes, rather than general ideas. The three predefined categories include a physical prototype, a digital prototype and an experience prototype. A “physical prototype” refers to a physical representation of an idea [5]. A “digital prototype” is a simulation of a part, product or complete installation that can be tested [6]. An “experience prototype” is a form of prototyping that enables design team members, users and clients to gain first-hand appreciation of existing or future conditions through active engagement with prototypes [7].

Why? As with the four categories, bingo selection uses predefined categories that enhance the degree of structure.

How? The categories can be chosen by the facilitator based on the specific requirements of the project or product. One example could be how the ideas gathered in the brainstorming or idea contest can be prototyped. The categories might be a physical prototype, a digital prototype or a prototype that can be experienced. Depending on the team size and amount of ideas, a short discussion is devoted for each idea.

Reflective Questions

What are the main differences between Bingo Selection and Affinity Diagrams?

What are the positive and negative aspects about the possibility of adding nested sub-categories?

If you have found many different categories, what would you do to further reduce the amount of groups?

How would you go about an idea that fits more than one category?

If you group by prototype applications, is it beneficial to focus on only one experience type (e.g. only on digital products)? What other categories could a facilitator choose for a business-oriented brainstorming session?

If you have a really large amount of ideas, would you rather try to categorize them into just a few categories using the Bingo Selection method or would you have many possible categories?

Your company only manufactures physical goods. How would you alter the format of the Bingo Selection method, since there is definitely no interest in digital or other goods?


  1. Scupin, R. (1997). The KJ method: A technique for analyzing data derived from Japanese ethnology. Human organization, 233-237.
  7. Buchenau, M., Fulton S.J. (2000): Experience prototyping. In: Proceedings Designing Interactive Systems, New York City, USA, ACM Press 424–433
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