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Pareto Charts

For a consumer product for which the causes of poor quality have been identified as follows:

b

For having a graphical overview of the frequency and the overall impact of the different problems, Pareto diagrams are used. It is easy to associate the most serious fault with the most frequent offender. The principle or rule where Pareto charts are based is that 80% of the problems incurred are caused by 20% of the sources (Juran’s (1988) “vital few, trivial many”). Therefore, focusing in this few problem sources, the vast majority of the problems can be solved, and, usually, some other small problems are usually associated with these (big affairs) groups. Dale, B.G. (1999)

Pareto chart where it can be seen the impact of the two first causes. Poor design and wrong part dimension are 2 of the 8 causes (20%) of obtaining poor quality.  These 2 causes together are generating 68.73% of the total number of defects.

Pareto chart where it can be seen the impact of the two first causes. Poor design and wrong part dimension are 2 of the 8 causes (20%) of obtaining poor quality. These 2 causes together are generating 68.73% of the total number of defects.

Thanks to the Pareto Chart, the main defect sources can be identified, and, efforts should be focus on improving this poor design and giving correct dimension to the parts. Very probably these causes are extremely connected with other defect causes as defective part assembly or surface abrasions. So, an improvement process reducing the impact of the 2 main causes will lead to an improvement and consequent defect reduction in some other secondary causes. In a meeting with the people in charge, the relation between these causes could be found out and discussed.

References:

  • Dale, B.G. (1999) Managing Quality. Third Edition. Blackwell Publishers Ltd, Oxford, UK
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