In the process of carrying out total quality management, cause-and-effect diagrams, flowcharts, histograms, checklists, scatter diagrams, array diagrams and control The tree diagram, matrix diagram, priority matrix diagram, process decision method diagram and activity network diagram are collectively referred to as the "New Seven Tools".
A Pareto chart (Pareto chart) is a special type of vertical bar chart used to identify the few important causes of most problems. The cause categories shown on the horizontal axis, as valid probability distributions, cover 100% of possible observations. The relative frequency of each specific cause on the horizontal axis gradually decreases until "other" is used to cover all other causes not specified. In a Pareto chart, bars are usually arranged by category to measure frequency or consequence.
The famous Italian economist Pareto (Pareto) proposed "the relationship between the critical minority and the irrelevant majority", which is called the 28 principle, that is, 80% of the problems are often caused by 20% of the reasons. Juran introduced this rule into product quality management to identify the most important of the many factors that cause product quality problems. is a common statistical analysis tool used to help identify and rank problems, as shown.
The left ordinate of the Pareto chart represents the number of occurrences of a certain factor, that is, the frequency; the right ordinate represents the cumulative frequency of the occurrence of a certain factor, that is, the frequency; The sizes are arranged in order from left to right.
Pareto analysis is also known as ABC analysis chart method. In the Pareto chart, the cumulative percentage of the main factors affecting the quality (cumulative frequency curve) is divided into three levels, and the corresponding factors are divided into three categories: frequency 0 %~80% are category A factors, which are the main factors affecting project quality; 80%~90% frequency are category B factors, which are secondary factors affecting project quality; 90%~100% are category C factors, which are General factors of project quality. Using the Pareto chart is helpful to determine the primary and secondary factors that affect the quality, so that the intricate problems can be seen at a glance.
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