Cause and effect analysis


Last Published  01 August 2012

  • Sufficient sheets of flipchart paper or a whiteboard
  • One marker pen per delegate
  • You might consider drawing up a briefing document explaining the diagrammatic elements of the exercise
  • Support material:
Time needed
Allow 1 hour overall to run this tool.
  • 20 minutes to identify families of causes
  • 20 minutes to brainstorm possible causes
  • 20 minutes to analyse the results.
Suggested steps
There are five key steps to cause and effect analysis:
  • define the problem (head)
  • name the causes (ribs)
  • brainstorm possible causes
  • incubate
  • evaluate the ideas.
Step 1: Define the problem
Start by defining the problem you are tackling: ideally, work with a real issue or problem facing the team or an individual. Not only does the training come alive because they are working with an issue they can touch or feel, but the results can be used directly back at work to help solve the problem.

Recording the ideas
There are several different ways you can record the ideas. Draw the outline diagram on a large whiteboard and give everyone a whiteboard marker pen to write their own ideas directly on the diagram. This approach is quick to set up and allows errors to be rubbed out easily.

Alternatively, draw the outline cause and effect diagram on several sheets of flipchart paper you have taped together. With a group of six to eight people you will need three sheets stuck together; more than nine, and you will need six sheets of flipchart paper. The big advantage is that you can take the diagram with you when the session is over.

A modification is to ask people to record their ideas on Post-it® notes, which can then be moved or grouped together as the diagram develops. This also has the advantage of minimising any fear of feeling foolish through having to write ideas publicly on the diagram.
Step 2: Name the ribs
Draw the horizontal 'spine' of the diagram and write the problem or 'effect' in the box on the right (at the 'head'). To make the diagram more fun, copy and laminate a fish head and tail, which you can stick on your diagram using Blu-Tack.

Now decide how many ribs (representing 'causes') to use, and what they will be called. There are several options you can take.

You might use the 'four Ms', which groups the causes of your problem into four major categories: manpower, methods, machines and materials. Or you might use PEM-PEM, which groups the causes of your problem into six major categories: plant, equipment, materials, people, environment and methods. Or you could just brainstorm your own list of likely families of causes. If you use the 'four Ms' approach, the diagram will look like The four Ms example.

Using three or six sheets of flipchart paper taped together also presents you with another problem - do you have a wall large enough to hang it on? If not, consider trying this rather bold approach. Lay the diagram flat on the floor and ask everyone to take their shoes off. There is something bizarre about taking one's shoes off in a conventional setting, which releases all sorts of inhibitions. Why take your shoes off? If you don't, you run the risk of tearing the diagram as people clamber over each other to write their ideas. Anyway, it is more fun!
Step 3: Brainstorm possible causes
You are now ready for the creative bit. First of all, confirm that everyone understands the rules of brainstorming, which are:
  • Get lots of ideas, however wild or crazy.
  • Never criticise ideas or people.
  • Piggy-back one idea on another.
  • Record all ideas – nothing should be discarded.
Explain that they will have about 15-20 minutes for the 'creative' part, and outline how energy levels are likely to vary.

For the first five minutes there will be plenty of energy as people write the obvious ideas.
Then there will be a plateau when things will seem to go quiet. After a short lull the energy and flow of ideas will start to pick up again, and plenty of different ideas will be generated.

Give everyone a pen and ask them to suggest possible causes of the problem or effect, writing them against a rib on the diagram. If they are not sure where an idea belongs, they can link it to another rib. If possible play music during this phase - something lively but not too loud, so that it motivates but does not take over.
Step 4: Incubate
Once the creative session is over allow incubation time for people to consider the list and see if anything else is missing. If possible, take a break, or wait until the following day before going any further. This time will often prompt valuable additions to the original list.
Step 5: Evaluate
Now you can move into the final, analytical stage when you evaluate how each idea contributes to the overall problem or 'effect'.

Ideally, you will need sufficient time to evaluate all the possible causes which have been listed. This may involve collecting additional data to confirm the status of what appear to be the root causes of the problem, because you simply cannot rely on 'gut feel' to move forward through the rest of the problem-solving process.

Draw a Pareto diagram
If time is short, you can use a quick and fairly rough approach to show how the team can focus on potentially promising ground. Give everyone 10 votes which they may 'spend' on the issues or causes they personally feel contribute most towards the problem. They can allocate one vote per item, all ten on one item, or a mixture. Once everyone has 'voted', identify the highest-scoring items on the diagram, and list them in numerical order. The pattern will probably reveal a Pareto outline, highlighting the few causes which might merit particular attention.

The Pareto principle, the 80:20 rule, suggests that a small number of possible causes (the 'vital few') will have a really significant impact on the whole problem. Your success in implementing effective solutions will be largely dependent upon your ability to identify the 'vital few' causes from the 'trivial many'. When interpreting Pareto diagrams consider the impact that individual items have - for example, if analysing accidents on a site, one fatal injury would be more important than hundreds of lesser injuries.