Cause and effect diagram (or fish bone diagram or Ishikawa diagram) - Case study




Ishikawa diagrams (also called fishbone diagrams, or herringbone diagrams , cause-and-effect diagrams, or Fishikawa) are causal diagrams that show the causes of a certain event -- created by Kaoru Ishikawa (1990).

 A common use of the Ishikawa diagram is in product design, to identify potential factors causing an overall effect and to help identify the root cause of non-conformances.

Ishikawa diagrams were proposed by Kaoru ishikawa in the 1960s, who pioneered quality management processes in the Kawasaki shipyards, and in the process became one of the founding fathers of modern management.

It was first used in the 1960s, and is considered one of the seven basic tools of quality management, along with the histogram, Pareto chart, check sheet, control chart, flowchart, and scatter diagram. See Quality Management Glossary. It is known as a fishbone diagram because of its shape, similar to the side view of a fish skeleton.

Causes

Causes in the diagram are often based on a certain set of causes, such as the 6 M's, described below. Cause-and-effect diagrams can reveal key relationships among various variables, and the possible causes provide additional insight into process behavior.


Causes in a typical diagram are normally grouped into categories, the main ones of which are:
  • The 6 Ms: Men/people, machines, methods, materials, measures, mother nature
  • 4 Ps - Places, Procedures, People, Politics
  • 4 Ss - Surroundings, Suppliers, Systems, Skills

Causes should be derived from brainstorming sessions. Then causes should be sorted through affinity-grouping to collect similar ideas together. These groups should then be labeled as categories of the fishbone. They will typically be one of the traditional categories mentioned above but may be something unique to our application of this tool. Causes should be specific, measurable, and controllable.)





Example : 2

Data analysis
Case study of  College of Engineering and Management Library

The management of Indira group of institutes has decided to promote the library as a central library of all the institutions run by Indira. Facing such an immense responsibility in a very short span of time made it obligatory to the library staff to organize the library system in a more better and competent way. Still being at its initial stage, the library activities were encountering many small problems frequently. To name few were:

1. Missing Books.
2. Misplacements.
3. Library usage.
4. Delivery of journals.
5. Number of copies per title.
6. Allocation of work among the staff.
7. Purchase related problems etc.


A committee was initiated to study the above problems and come out with efficient solutions to meet the requirements of the management. Lot of brainstorming was conducted and it was decided to solve these problems by implementing 'Quality Circle Program'.

A group was created and the problem of missing books was selected for observation on preferential basis. It was decided to solve the above problem by cause and effect analysis and the same was presented in the following diagram before the management committee:

The management acknowledged the solutions and accepted to implement the same on urgent basis. It helped the library to come out with great solutions. It was also noticed during the above operation that Quality Circles, if productively put into practice it can crack countless variety of problems in any context of expertise.