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The Affinity Diagram (KJ Analysis)

Quality Tools > Tools of the Trade > 4: The Affinity Diagram (KJ Analysis)


What's it for?

Some problems are really messy. You have lots of pieces of information that do not seem to fit together. To make matters worse, much of the information is scattered around the place and is probably not written down. People disagree about what the real problem is (if the get that far) and meetings achieve nothing, breaking up in disarray.

This kind of problem is something of a quality professional's nightmare. There is seldom any solid quantitative data available to nail things down – it is all snippets and pieces of qualitative gossip and opinion.

The Affinity Diagram is just the tool for solving this kind of mess, and KJ is the most common way of building the diagram.

It is also useful as a way of organising the results of a Brainstorm, where you start with a creative idea in mind and generate number of possible ideas around it.


How does it work?

Problems often come in little pieces and can seem like a jigsaw puzzle, waiting to be solved. The pieces of the puzzle are often held in the heads of various experts and people with pertinent experience. The first task must thus be to collect those pieces. These are often small 'chunks' which can be written down in a relatively small space.

The next task is to make sense of the jigsaw pieces–in effect to start to build the puzzle. Think about how you do a puzzle: most people will do multiple levels of sort. First, they sort out the side, corner and middle pieces. They then sort out similar middle pieces (all the blue sky pieces, all the brown boat, etc.). They piece together the identified elements of the jigsaw, then build the final picture out of the completed elements.

We can use this same technique for solving more general problems. To be able to organise the individual elements of the problem, we simply write these individual chunks on 3" x 5" cards or Post-it (cards are more durable, but Post-its stay where they are put–even on vertical surfaces). The cards may then be moved into similar groups. Each group is named with a header card and the groups are again grouped into larger groups. In this way a hierarchy or tree is built, bottom-up. The result is known as an Affinity Diagram, and is shown in Fig. 1.

Fig. 1  Affinity Diagram components

KJ, by the way, stands for Kawakita Jiro, the inventor of a simple technique for building Affinity Diagrams. The key principle is that everyone works together in silence. The idea is that this allows the more creative right brain to come into play. In practice, it also has the not insignificant benefit that it keeps people focused on sorting out the problem, rather than getting sidetracked in discussion.


How to do it

1.     Identify what you are trying to achieve, for example, 'Understand why people keep leaving' or 'Organise ideas for garden design'.


2.     Write all the ideas down on 3" x 5" cards or Post-its. Use marker pens to make them legible from a distance, so you can stand back and see the big picture. This can be done as a group or with ideas collected beforehand. Write the ideas in short phrases or sentences so they are understood 'stand-alone'. Thus, 'Petunias in front bed' is more descriptive of a thought than just 'Petunias'. Put the resulting ideas in a 'parking area' to one side of the main work area.


3.     Silently, the whole group works simultaneously, moving cards from the parking area into the main work area, as in Fig. 2. Cards that seem to be related in some way are put together (typically in columns). It is often useful to be creative in this grouping rather than using simple logical organisation, as this can give new insights into the problem.

        If you disagree with someone, you can move their cards or make a duplicate (as can they). You can also add new cards as ideas occur to you.

        If card groups get too big (eg. ten or more cards), consider breaking them down into several smaller groups.

Fig. 2  Moving the cards    

4.     When you have stopped moving cards, discuss each group and add a header card to describe the group. The discussion at this time may result in moving cards around as you begin to better understand the problem.

        This understanding may be enough to give you a good picture of the problem. You can also proceed to step 5 to get a more detailed understanding.


5.     Repeat steps 3 and 4 with the header cards. This will result in a more complete picture being built up. When you are done, you can draw the result as Fig. 3, showing the hierarchy as a series of nested groups.


Fig. 3  Exit interview comments from checkout operators


Next time: Failure Mode Effects Analysis


This article first appeared in Quality World, the journal of the Institute for Quality Assurance

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