Paretos’ Diagram Concept

Paretos’ Diagram constitutes one of the tools used in quality control and was initially defined by Joseph Juran in 1950, the quality guru. On its basis is the Paretos’ Principle which refers that a small number of causes (generally 20%) are responsible for the majority of problems (80%). The high applicability of this principle to the resolution of quality problems lies precisely in the fact to help identify the reduced number of causes that are many times behind a big part of the problems that occur. Is in the detection of the 20% of causes that originate 80% of the effects that Paretos’ Diagram, reveals to be a very efficient tool. In fact, Paretos’ Diagram says that, in many cases, the most part of the losses are due to a small number of defects considered as vital (vital few). The remaining defects, that originate little losses, are considered trivial (trivial many) and don’t represent any serious danger. Once identified the vital few, should proceed to its’ analyses, study and processes implementation that lead to its’ reduction or removal.     

Paretos’ Diagram graphic presentation: In the construction of Paretos’ Diagram is used a bars and lines graphic, in which in the bars are presented the frequencies of occurrences by decreasing order and in the lines the cumulated frequencies. Through this diagram is possible to observe the contribution of the main causes to a certain event.

 

Translated from Portuguese by Susana Saraiva, Portuguese-English and English-Portuguese translation specialist. Contact: spams@sapo.pt.