What is it: A Fishbone Diagram or otherwise known as a "Cause and Effect" or "Ishikawa" Diagram will help to visually display the many potential causes for a specific problem or effect.The Fishbone Diagram is used to help workers focus on the causes of a problem rather than the symptoms. The results of a Fishbone Diagram may lead to other activities such as Brainstorming, FMEA's, Multi-vari charts, ANOVA, regression analysis or DOE activities.
Fishbones Diagrams have a box at the right hand side where the effect is written and is examined. The main body of the diagram is a horizontal line from which stems the general causes, represented as "bones". These "bones" are drawn towards the left-hand side of the paper and are each labeled with the causes to be investigated, often brainstormed beforehand and based on the major causes listed above the line. Off each of the large bones there may be smaller "bones" highlighting more specific aspects of a certain cause, and sometimes there may be a third level of bones or more depending on the complexity of the problem.
The "bones" can be found using the '5 Whys' technique. When the most probable causes have been identified, they are written in the box along with the original effect. The more populated bones generally outline more influential factors, with the opposite applying to bones with fewer "branches". Further analysis of the diagram can be achieved with a Pareto chart.
Why use it: It is particularly useful in a group settings and for situations in which little quantitative data is available for analysis.
What is it used for: Similar to Affinity Grouping, The Fishbone Diagram is used to group items. However, the grouping is done in a more structured manner; inputs (causes) are categorized to show how they lead to the output (or the effect.)
When to use it:
How to use it: The general procedure is:
Once you have the branches labeled, begin brainstorming possible causes and attach them to the appropriate branches. For each cause identified, continue to ask 'why does that happen?' and attach that information as another bone of the category branch. This will help get you to the true drivers of a problem. Causes in a typical diagram are normally arranged into categories, the main ones of which are: Causes in the diagram are often based around a certain category or set of causes, such as the 6 M's, 8 P's or 4 S's