This guide provides instructions on performing a process capability analysis for multiple continuous process variables simultaneously. This platform produces a set of reports and graphs that are designed to compare the performance of the different process variables to each other.
The Capability Analysis Dialog
- From an open JMP® data table, select Analyze > Quality and Process > Process Capability.
- Select one or more continuous variables from Select Columns (continuous variables have blue triangles), click Y, Process, and click OK.
If specification limits have not been entered as a column property for each of the measures, or if there is an error, you will receive an error window. Click OK. The resulting window allows you to correct specification limits or select a data table with the limits stored.
Additional Options:
- To skip the spec limits dialog, click No (skip columns with no spec limits) under Show Spec Limits in the opening Dialog Box.
- To specify subgroupings use Process Subgrouping.
- To specify sigma use Historical Information.
- To perform capability studies for nonnormal data use Distribution Options.
The Process Capability Analysis Report
JMP produces three graphical summaries of the capability of each measure. For these graphs, measures have been standardized to the spec limits.
- Goal Plot: Measures with a Ppk > 1.0 are plotted inside the triangle, and measures with a Ppk < 1.0 are plotted outside the triangle. The position of each point relative to the axes provides information on spread (y-axis) and centering (x-axis) of each measure relative to the spec limits. Choose Shade Levels under Red Triangles to add color.
- Capability Box Plots: Box plots for each variable.
- Capability Index Plot: The Ppk of each point.
Notes: Use the sliders to change the cutoff for acceptable Ppk. Additional options, such as Individual Detail Reports and Summary Reports, are available from the top red triangle menu.
Visit Quality and Process Methods > Process Capability in JMP Help to learn more.