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Ishikawa diagrams (also called fishbone diagrams, herringbone diagrams, cause-and-effect diagrams) are
The ''defect'' is shown as the fish's head, facing to the right, with the ''causes'' extending to the left as fishbones; the ribs branch off the backbone for major causes, with sub-branches for root-causes, to as many levels as required.
Ishikawa diagrams were popularized in the 1960s by
Root-cause analysis is intended to reveal key relationships among various variables, and the possible causes provide additional insight into process behavior.
The causes emerge by analysis, often through brainstorming sessions, and are grouped into categories on the main branches off the fishbone. To help structure the approach, the categories are often selected from one of the common models shown below, but may emerge as something unique to the application in a specific case.
Each potential cause is traced back to find the root cause, often using the
causal diagram
In the philosophy of science, a causal model (or structural causal model) is a conceptual model that describes the causal mechanisms of a system. Causal models can improve study designs by providing clear rules for deciding which independent ...
s created by Kaoru Ishikawa
was a Japanese organizational theorist and a professor in the engineering faculty at the University of Tokyo noted for his quality management innovations. He is considered a key figure in the development of quality initiatives in Japan, particul ...
that show the potential causes of a specific event.
Common uses of the Ishikawa diagram are product design and quality defect prevention to identify potential factors causing an overall effect. Each cause or reason for imperfection is a source of variation. Causes are usually grouped into major categories to identify and classify these sources of variation.
Overview
The ''defect'' is shown as the fish's head, facing to the right, with the ''causes'' extending to the left as fishbones; the ribs branch off the backbone for major causes, with sub-branches for root-causes, to as many levels as required.
Ishikawa diagrams were popularized in the 1960s by Kaoru Ishikawa
was a Japanese organizational theorist and a professor in the engineering faculty at the University of Tokyo noted for his quality management innovations. He is considered a key figure in the development of quality initiatives in Japan, particul ...
, who pioneered quality management processes in the Kawasaki shipyards, and in the process became one of the founding fathers of modern management.
The basic concept was first used in the 1920s, and is considered one of the seven basic tools of quality control. It is known as a fishbone diagram because of its shape, similar to the side view of a fish skeleton.
Mazda Motors famously used an Ishikawa diagram in the development of the Miata
The Mazda MX-5 is a lightweight two-passenger roadster sports car manufactured and marketed by Mazda with a front mid-engine, rear-wheel-drive layout. The convertible is marketed as the or in Japan, and as the Mazda Miata () in the United Sta ...
( MX5) sports car.
Root causes
Root-cause analysis is intended to reveal key relationships among various variables, and the possible causes provide additional insight into process behavior.
The causes emerge by analysis, often through brainstorming sessions, and are grouped into categories on the main branches off the fishbone. To help structure the approach, the categories are often selected from one of the common models shown below, but may emerge as something unique to the application in a specific case.
Each potential cause is traced back to find the root cause, often using the 5 Whys
Five whys (or 5 whys) is an iterative interrogative technique used to explore the cause-and-effect relationships underlying a particular problem. The primary goal of the technique is to determine the root cause of a defect or problem by repeating ...
technique.
Typical categories include:
The 5 Ms (used in manufacturing)
Originating with lean manufacturing and theToyota Production System
The Toyota Production System (TPS) is an integrated socio-technical system, developed by Toyota, that comprises its management philosophy and practices. The TPS is a management system that organizes manufacturing and logistics for the automobile m ...
, the 5 Ms is one of the most common frameworks for root-cause analysis:
*Manpower / mind power (physical or knowledge work, includes: kaizens, suggestions)
*Machine (equipment, technology)
*Material (includes raw material, consumables, and information)
*Method (process)
*Measurement / medium (inspection, environment)
These have been expanded by some to include an additional three, and are referred to as the 8 Ms:
*Mission / mother nature (purpose, environment)
*Management / money power (leadership)
*Maintenance
The 8 Ps (used in product marketing)
This common model for identifying crucial attributes for planning in product marketing is often also used in root-cause analysis as categories for the Ishikawa diagram: *Product (or service) *Price *Place *Promotion *People (personnel) *Process *Physical evidence (proof) *PerformanceThe 4 or 5 Ss (used in service industries)
An alternative used for service industries, uses four categories of possible cause: *Surroundings *Suppliers *Systems *Skill *Often an important 5th S is added - SafetySee also
* Seven Basic Tools of Quality *Five whys
Five whys (or 5 whys) is an iterative interrogative technique used to explore the cause-and-effect relationships underlying a particular problem. The primary goal of the technique is to determine the root cause of a defect or problem by repeating ...
*Issue map
The issue-based information system (IBIS) is an argumentation-based approach to clarifying wicked problems—complex, ill-defined problems that involve multiple stakeholders. Diagrammatic visualization using IBIS notation is often called issue ...
*Issue tree
An issue tree, also called logic tree, is a graphical breakdown of a question that dissects it into its different components vertically and that progresses into details as it reads to the right.
Issue trees are useful in problem solving to ide ...
*Resource management
In organizational studies, resource management is the efficient and effective development of an organization's resources when they are needed. Such resources may include the financial resources, inventory, human skills, production resources, or i ...
References
Further reading
* Ishikawa, Kaoru (1990); (Translator: J. H. Loftus); ''Introduction to Quality Control''; 448 p; * Dale, Barrie G. et al. (2007); ''Managing Quality 5th ed''; {{DEFAULTSORT:Ishikawa diagram Causal diagrams Causality Knowledge representation Quality control tools Japanese inventions