Affinity diagram and related tools

The affinity diagram is the best known of the set of Seven Management and Planning Tools that were developed in Japan in the 1960s.

The 7 MP tools were designed to complement the traditional 7 quality control tools (which remain the foundation of the modern lean six sigma toolkit). Whereas the 7 QC tools are designed to represent and quantify the operation of a process, the 7 MP tools are designed to work with unstructured data, building a shared picture from the input of several participants with differing perspectives on the situation.

The 7 MP tools are valuable in the Define phase for organising views on customer and stakeholder requirements, and are also very useful in the Improve phase as a preliminary planning tool.

We will look here at three of the seven tools and how they fit together to provide a basis for planning.

Affinity diagram


The initial gathering of information is done by a group, ideally of about 6 people, who silently brainstorm ideas relating to a focus statement that has been discussed and agreed between the facilitator and the team. A typical focus statement might be "what do we need to do to ensure successful implementation of project X". Each member of the group writes as many relevant ideas as come to mind, each idea on a separate card or PostIt note. The ideas should be short, stand alone, statements. For the example here one would want each idea to be phrased as an action statement. It is important that this writing is done in silence. It usually takes around 15 minutes for people to come up with their thoughts. It's worth persevering for a few minutes after the initial rush of ideas are set down. With six people one would be looking for at least 100 ideas - it doesn't matter if there is duplication.

The idea cards are then set out, again in silence, on a large work area (a wall for stickies or a table for cards). At this point the ideas will be in random order. The team should each read through the whole set of ideas, in silence, at the end of which period it is permitted for people to ask questions if needed solely for the purpose of clarifying any idea cards.


The facilitator then calls for silence and asks the team to physically move the cards around on the workspace so that like ideas are grouped - clustered - together.

The value of the Affinity technique is that we allow the essence of each cluster to emerge, rather than to be imposed from an arbitrary set of categories. (This is the key difference between an affinity diagram and a cause and effect diagram in which the categories are predetermined).

We are looking for around 8 to 12 clusters from the 100 + individual ideas.


Once the ideas are clustered - shown here by being laid out in columns - the team is asked to come up with a header for the cluster, again as a short stand alone statement.

The statement should capture the intent of the cluster. After creating the header, double check the individual ideas to see if they still fit.

Inter-relationship diagraph


Now we have 8 to 12 named clusters we want to see how they are related to each other. Copies of the cluster headers should be set out like a clock face. Each pair of cluster headers is then compared, asking two questions.

  • Are these two items related?
  • If so, which is the inflencer and which is the dependent?

There may be some trial and error here to judge which relationships to capture. Obviously, everything is related by virtue of being in response to the same focus statement. However, if the clusters have been thoughtfully grouped and named we can usually come up with a balanced level of connection that identifies the salient relationships. We draw an arrow from the influencing cluster header to the dependent cluster header. (The illustration here shows the first few items only).

Once all the pairs have been compared, we need to tally and record the number of arrows in and the number of arrows out for each of the clusters.

 Sequence Diagram


Using the count of in and out arrows, we "plot" a copy of each cluster on to a scatter chart with the in arrow count on the x axis and the out arrow count on the y axis.

What this gives us is a graphic representation of the logical flow of dependencies. At the top left are cluster headers with few in arrows and many out arrows - these are the items that are candidates for being done early in the project, because they depend on few other items but influence many.

Conversely at the bottom right we find items that appear to depend on several other items, and hence are candidates for commencement later in the project after the influencing items have been addressed.


The affinity / inter-relationship / sequence process can be carried out with a small group in a couple of hours. It's worth taking the time to clarify and agree the focus statement at the beginning of the process. Large groups can be unwieldy and may leave some of the participants feeling left out. Groups that are too homogenous may not generate any fresh insights.

However, with a diverse group of say 6 - 8 this process can identify significant points that may not have been on the radar for all participants. If the silent generation and clustering method is followed, the process will generate an outline plan that will make sense to all participants and can be used as a basis for more detailed planning - which is the domain of the remaining 4 of the 7 MP tools.