Example of a Constant Sample Size across Groups
This example uses Pareto plots to compare the causes of failure during the fabrication of integrated circuits for two different processes. Each process has a constant sample size of 1000. The data table in this example lists the causes of failure and the number of times each type of defect occurred.
1. Select Help > Sample Data Folder and open Quality Control/Failures.jmp.
2. Select Analyze > Quality and Process > Pareto Plot.
3. Select Causes and click Y, Cause.
4. Select Process and click X, Grouping.
5. Select Count and click Freq.
6. Select Per Unit Analysis and then select Constant.
7. Enter 1000 in Sample Size.
8. Click OK.
Figure 15.9 Pareto Plot Report Window
Process A indicates Contamination as the top failure while Process B indicates Oxide Defect as the leading failure.
9. Click the Pareto Plot red triangle and select Test Rates Across Groups.
Figure 15.10 Test Rates across Groups Results
Note that the DPU for Contamination across groups (Process A and B) is around 0.06.