Aim
Fishbone diagrams are usually used during brainstorming, to identify clusters of causes which can lead onto prioritising these issues and finding out the root causes.
Benefits
The fishbone diagram is an excellent brain storming tool to use with a team to capture a whole range of issues or causes that are causing an Effect and start to group them into clusters.`The technique is used when data on the cause categories is not available or difficult to obtain. The Fishbone is really an affinity diagram in the shape of a fish bone.
How does it work
The best way to start a fishbone diagram is with a large piece of paper and post it notes. Draw a fishbone shape. The Effect is a bit like the problem you are solving or the current outcome that needs fixing and this is written in the head of the fish eg ‘Customer enquiry response time takes too long’. You can add a secondary measure if needed eg ‘Product sent has too many defects’ Add a few metrics if you have them but don’t make it too wordy. So an ideal Effect would be ‘Customer response time >6mins. 15% of deliveries have defects.’
Now the team need to write as many post-its as they can of issues/causes/factors/inputs that are driving the Effect. A good post it has 3-5 words , some explanation but not too much. Avoid one word post its eg ‘Inventory’ otherwise it will lead to lack of clarity later ie do you need more inventory?, do you have too much inventory?, is there an inventory bottleneck? .
The Fishbone is a brainstorming exercise so the causes post it’s should be completed individually by the team involved with the process without too much chatter. Don’t allow one person to write all the post its – it tends to kill creativity.
When everyone has finished writing them (no rush) then post them up in no particular order all over the fishbone. Then is mini teams of 3-4 people take turns to arrange them into topics/clusters along the bones. Finally title the bone with a different coloured post-it. You now have your causes clustered into manageable topics (often 7-8 seems to be a typical number)
Here’s what a completed fishbone looks like.
You can smarten the fishbone up later but I’m happy just to extract the key issue clusters – there is a number of software packages (eg SigmaXL and SmartDraw) that will do this. I try and avoid giving the topics fixed (manufacturing) titles like this fishbone below – develop them as you go. It’s ok however to make short lists of secondary causes as shown below.
