Pareto plot of QC seven tools is also called Pareto plot, 8020 plot, etc. It is a chart used to arrange the quality improvement projects from the most important to the least important. In form, it is composed of two charts, one is a histogram marking the frequency of each project, and the other is a line chart marking the cumulative percentage of the project. The main purposes of the arrangement chart are: to show the impact of each quality improvement project on the whole quality problem in order of importance; Identify opportunities for quality improvement
Figure 1 conventional arrangement chart
Figure 1 shows a company that produces electronic products. In terms of Futures: the coke 1609 contract fluctuated downward, it counted the defect records in recent production and sorted them into an arrangement chart form. Obviously, the frequency of "missing screens" is significantly higher than that of "missing clips", "leaky gasskets" and other defects. We should seize this opportunity and take it as the main direction of quality improvement, which is worthy of in-depth investigation, research and analysis
when applying the Pareto Diagram, it should be noted that the main purpose of drawing the Pareto Diagram is to eliminate the secondary "majority" and find the key "minority". Therefore, when you find that the downward trend of the histogram is slow and the gap between the head item and the tail item is not large, you can try to adjust it with the following methods:
1 The vertical coordinate of the histogram is not represented by "pieces", but by other quantifiable indicators (such as "amount", etc.)
2. The abscissa is not represented by "defect", but by other classification indicators (such as "product type")
3. add hierarchical variables (such as "time", etc.) and draw a "hierarchical Pareto plot"
the purpose of all these methods is to find the main contradiction in the disordered data more quickly and accurately
jmp software knows the importance of these details in practical work, so it provides corresponding options on its "Pareto Diagram" platform. For example, if we record the date (Oct1, OCT2 or OCT3) and the catalogue of foreign investment advantageous industries in the central and western regions when recording defects, and pay attention to giving full play to the advantageous equipment cleaning status (before or after) such as local characteristic resources, we can refine a layout chart that reflects the whole into 6 (=3*2) or more hierarchical layouts that reflect the category information of the two dimensions (as shown in Figure 2). In this way, we can more clearly observe the defect distribution on different dates and under different equipment cleaning conditions, so that we can find out the key problems. At the same time, it can also be used to compare the product quality under different conditions of normal operation and low-speed operation
Figure 2 hierarchical arrangement chart
in addition, there is another trick: considering that some domestic enterprises are used to analyzing such quality problems with simple graphics such as pie charts, JMP soft slat wrote in his blog: "based on the experience and lessons we have learned from the test this month, the" Pareto chart "platform provides a fast conversion between" arrangement chart "and" pie chart ". Figure 3 is a pie chart displayed after sorting the defect categories, which can also be used for a simple analysis of the "Pareto phenomenon"
the arrangement chart converted from Figure 3 to pie chart