Subgroup samples of four cans are selected and weighed every hour for twelve hours. Each observation in the Oil1 Cusum.jmp data table contains one value of weight and its associated value of hour. The observations are sorted so that the values of hour are in increasing order. You want to be able to detect a 2σ shift in the process.
1.
Select Help > Sample Data Library and open Quality Control/Oil1 Cusum.jmp.
2.
Select Analyze > Quality and Process > CUSUM Control Chart.
3.
Select weight and click Y.
4.
Select hour and click X.
5.
Figure 4.6 CUSUM Control Chart with Subgroups
Note: Montgomery (2013) states that “only if there is some significant economy of scale or some other valid reason for taking samples of size greater than one should subgroups of size greater than one be used with the CUSUM.” The use of rational subgroups in the tabular CUSUM chart does not always improve the performance of the chart.

Help created on 10/11/2018