Figure 3.8 Example of a Control Chart
Subgroups should be chosen rationally, that is, they should be chosen to maximize the probability of seeing a true process change between subgroups.
When you double-click the x or y axis, the appropriate Axis Specification window appears for you to specify the format, axis values, number of ticks, gridline, reference lines, and other options to display on the axis.
For example, the Pickles.jmp data lists measurements taken each day for three days. In Figure 3.9, by default, the x axis is labeled at every other tick. Sometimes this gives redundant labels, as shown to the left in Figure 3.9. If you specify a label at an increment of eight, the x axis is labeled once for each day, as shown in the chart on the right.
Figure 3.9 Example of Labeled x Axis Tick Marks

Help created on 10/11/2018