Known As A Cause And Effect Diagram example essay topic

What is a fishbone diagram? A fishbone diagram, also known as a cause-and-effect diagram, is a visual tool used to systematically list the different causes that can be attributed to a problem (or an effect). This tool is most useful in identifying the reasons why a process goes out of control. Its' creator, Dr. Kaoru Ishikawa of Tokyo University, developed this technique in 1943 to address process inefficiencies found within the Kawasaki shipyards of Japan. Causes within a cause and effect diagram are typically made up major categories. The categories themselves may be anything that is appropriate to the problem that is being analyzed, however, you will often see: o Manpower, methods, materials, and machinery (in a manufacturing environment) o These are known as the 4 M's o Place, policies, procedures, and people (in an administration or services environment) o These are known as the 4 P's o Surroundings, Suppliers, Systems, Skills (all environments) o These are known as the 4 S's While these guidelines can and are helpful, they should not be used, however, if they limit the information that could be contained within the diagram or are inappropriate for the given problem.

According to Dr. Ishikawa (1982) there are three main applications of cause-and-effect, or fishbone, diagrams (p. 18): 1. Cause enumeration is one of the most widely used graphical techniques for quality control and improvement. It usually develops through a brainstorming session in which all possible types of causes (however remote they may be) are listed to show their influence on the problem (or effect) in question. Cause enumeration facilitates the identification of root causes because all conceivable causes are listed.

2. In Dispersion analysis, each major cause is thoroughly analyzed by investigating the sub-causes and their impact on the quality characteristics (or effect) in question. The key to this diagram's effectiveness lies in the reiteration of the question, "Why does this dispersion occur?" This diagram helps us analyze the reasons for any variability, or dispersion. Unlike cause enumeration where smaller causes that are considered insignificant are still listed, in dispersion analysis, causes that don't fit the selected categories are not listed. In other words, the weak point is that the form the diagram takes often depends on the individuals making it, and that sometimes-small causes are not isolated or observed. Consequently, it is possible that some root causes will not be identified in dispersion analysis.

3. When cause-and-effect diagrams are constructed for process analysis, the emphasis is on listing the causes in the sequence in which the operations are actually conducted. The advantage of this diagram is that, since it follows the sequence of the production process, it is easy to assemble and understand. The disadvantage is that similar causes appear again and again, and causes due to a combination of more than one factor are difficult to illustrate. Having an understanding of what a fishbone diagram is does one no good if one does not know how or when to utilize such a tool.

The North Carolina Department of Environment and Natural Resources suggests the team that has been formed to address a specific problem ask themselves the following questions: Does the team... o Need to study a problem / issue to determine the root cause? o Want to study all the possible reasons why a process is beginning to have difficulties, problems, or breakdowns? o Need to identify areas for data collection? o Want to study why a process is not performing properly or producing the desired results? Now that one realizes what a fishbone diagram is, and how to properly utilize this analysis tool, the question becomes one of action. How is the tool to be used? How is the fishbone diagram constructed? This tool was named fishbone due to the resemblance of the skeletal structure of a fish. In order to use this technique, one would physically draw this skeletal representation, using each part drawn to list possible causes and effects of the problem that is listed at the "head" area of the fish.

From the "bones" drawn that list the categories, smaller bones are drawn that lead off each category to list effects of the problem within that category. Again, this procedure is followed with "bones" being drawn off of each of the causes that list possible causes for the effect. All this can be summed into an eight-step process: 1. Draw the fishbone diagram... 2. List the problem / issue to be studied in the "head of the fish".

3. Label each " "bone" of the "fish" with the categories mentioned earlier Note: You may use one of the four categories suggested, combine them in any fashion or make up your own. The categories are to help you organize your ideas. 4.

Use an idea-generating technique (e. g., brainstorming) to identify the factors within each category that may be affecting the problem / issue and / or effect being studied. The team should ask... "What are the machine issues affecting / causing ?" 5. Repeat this procedure with each factor under the category to produce sub-factors. Continue asking, "Why is this happening?" and put additional segments each factor and subsequently under each sub-factor. 6.

Continue until you no longer get useful information as you ask, "Why is that happening?" 7. Analyze the results of the fishbone after team members agree that an adequate amount of detail has been provided under each major category. Do this by looking for those items that appear in more than one category. These become the 'most likely causes". 8. For any items identified as the "most likely causes", the team should reach consensus on listing those items in priority order with the first item being the most probable" cause.

It is important to understand that this technique is not for problem identification. To fully utilize this analysis tool, the problem to be addressed must be clearly defined and agreed upon by all parties.