Cause & Effect Analysis (Fishbone Diagrams)
Cause & Effect diagrams (also called Fishbone or Ishakawa diagrams) were developed in the 1950ís by Ishakawa, the Japanese Statistician, for use by Quality Circles which he also developed.
They are a structured and visual brainstorming tool designed to help a team to identify all the possible causes of the problem that they are trying to solve. When completed, they provide a Map of the problem and are particularly useful in the first two meetings of a team when they are embarking on their diagnostic journey.
A local office in a government department found that papers and articles (scientific ones) took months to circulate to all the people on the circulation list. In a one hour session, an action team brainstormed possible reasons and causes and created the following fishbone. A voting exercise highlighted three items as being the main causes and they then went on to tackle and resolve them.
The general procedure is:
Step 1 - An initial Brainstorm of 20 or so possible causes of the problem.
- Form a group of 5 to 10 people and elect a Scribe.
- As a group, brainstorm Possible Causes of the Problem writing all ideas on the Flip Chart.
- Try to avoid people offering solutions at this stage.
- Adhere to the Brainstorming Rules.
Step 2 - Draw your first Fishbone
- From those ideas identify the Main Headings of the Fishbone.
- Some common ones are ( Manpower, Machines, Materials, Methods, Environment) and (People, Procedures, Process, and Product). If these do not apply then choose your own.
- Draw a Fishbone Diagram with the "Problem" at the Head, putting the "Main Headings" on each of the main spines.
- Transfer the brainstormed "Possible Causes" to the relevant spines.
Step 3 - Brainstorm further onto the Fishbone
- Take each Spine in turn and brainstorm further possible causes.
Step 4 - Vote & Prioritise
- Each person uses 5 Votes and ticks those "Possible Causes" that they feel are the most likely ones.
- Circle the top 6 or 7 items in the voting. These are the priority ones to focus on.
Step 5 - Action Plan
- Draw-Up a simple "Action Plan" as to how you would progress further over the coming month or two. e.g. what information you might collect, any quick fixes needed, what changes you might consider
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