Use Capability Sixpack - Between/Within to assess the capability of an in-control process when the variation in the data has both within-subgroup and between-subgroup components. A capable process is able to produce products or services that meet specifications.

For example, a process for coating paper with a thin film may have both between-subgroup and within-subgroup variation. The within-subgroup variation is the variation is film thickness within one roll (subgroup). If the machine is reset for each roll, then there might be variation between rolls (subgroups).

The process must be in control before you assess capability. If the process is not in control, then the estimates of capability will be incorrect.

Capability Sixpack for between-subgroup and within-subgroup variation consists of capability statistics and tools for assessing whether the data are in control and normally distributed.

A manufacturing process coats large rolls of paper with a thin film. Three measurements of coating thickness are taken from 25 consecutive rolls. The machine is reset for each new roll, so in addition to the variation within a roll there is a significant source of variation between rolls. The film thickness must be 50 + 3 microns to meet engineering specifications.

Data: Film.MTW (available in the Sample Data folder).