Quality and Process Methods > CUSUM Control Charts > CUSUM Control Chart Platform Options
Publication date: 04/12/2021

CUSUM Control Chart Platform Options

The CUSUM Control Chart red triangle menu contains the following options:

Show Limits

Shows or hides the upper and lower decision limits in the CUSUM Chart.

Show Center Line

Shows or hides the center line in the CUSUM Chart.

Show Shift Lines

(Available only when there is a shift detected in the data.) Shows or hides the vertical lines in the CUSUM Chart that designate shifts. Shift lines are drawn at the start of a shift.

A positive shift occurs when the value of C+ exceeds the upper limit on the chart. The start of the shift is defined as the first point after the most recent zero value for C+.

A negative shift occurs when the value of C- falls below the lower limit on the chart. The start of the shift is defined as the first point after the most recent zero value for C-.

Show ARL

Shows or hides the Average Run Length (ARL) report. See Average Run Length (ARL) Report.

ARL Profiler

Shows or hides a profiler of average run length versus the parameters h and k. If you have specified the Data Units option in the launch window, the profiler plots average run length versus the parameters H and K.

The average run length (ARL) for a specified shift is the average number of runs expected before an out-of-control signal occurs. For example, the ARL at 0 represents the average number of runs expected before a false-alarm signal occurs when the process is in control. When the process is in control, the shift size is 0.

The ARL Profiler enables you to explore how various settings of the parameters affect the performance of the corresponding CUSUM chart. As the parameters in the Control Panel report are updated, the ARL Profiler is updated as well. An ideal CUSUM chart has a high ARL(0) value and a low ARL(Δ) value, where Δ is the size shift that is of interest.

The ARL Profiler depends on the settings of the Upper Side and Lower Side options in the Control Panel report:

If both the Upper Side and Lower Side options are selected, the profiler represents the average run length for crossing either the upper or lower decision limits on the CUSUM chart.

If only the Upper Side option is selected, the profiler represents the average run length for the upper decision limit on the CUSUM chart.

If only the Lower Side option is selected, the profiler represents the average run length for the lower decision limit on the CUSUM chart.

For more information about the options in the red triangle menu next to ARL Profiler, see Profiler in Profilers.

Control Panel

Shows or hides a report of the current values of the parameters. This report enables you to change the parameter values as well as the sidedness of the CUSUM chart.

Parameters Report

Shows or hides a report of the current values of the parameters.

Test Beyond Limits

Shows or hides a red circle around any point that is above the upper limit or below the lower limit in the CUSUM chart.

Save Summaries

Creates a new data table that contains statistics for each subgroup in the CUSUM chart. The following statistics are saved to the new data table: the subgroup number and size, the subgroup sample mean, an indicator of shift starts, a value that indicates each interval between shift starts, the upper and lower cumulative sums and corresponding consecutive run counts, and the LCL and UCL values.

Tune Chart

Shows or hides a control that enables you to set an acceptable range for the Y variable. Adjust the minimum and maximum values of the acceptable range and click Done. At this point, the CUSUM chart updates based on a new value of the k parameter.

If you specified the Data Units option in the launch window, the imputed k parameter is the average of the minimum and maximum values divided by the Sigma parameter.

If the Data Units option is not specified, the imputed K parameter is the average of the minimum and maximum values.

Setting the acceptable range for the Y variable enables you to set the practical significance of the CUSUM chart. This is particularly helpful when the testing interval is more frequent, which can result in a much shorter practical average run length.

Reset to Defaults

Resets all parameters back to their default values.

Alarm Script

Enables you to write and run a script that indicates when the data fail special causes tests. Results can be written to the log or spoken aloud, and there is an option to include an explanation of why the test failed. You can also send results to an email using the custom script option.

As an Alarm Script is invoked, the following variables are available, both in the issued script and in subsequent JSL scripts:

qc_col is the name of the column

qc_test is the test that failed

qc_sample is the sample number

Tip: After an alarm script is specified, the alarm script is invoked when the Test Beyond Limits option is turned on.

See Run Alarm Scripts in the Scripting Guide for more information about writing custom Alarm Scripts.

See Redo Menus in Reports and Save Script Menus in Reports in Using JMP for more information about the following options:

Redo

Contains options that enable you to repeat or relaunch the analysis. In platforms that support the feature, the Automatic Recalc option immediately reflects the changes that you make to the data table in the corresponding report window.

Save Script

Contains options that enable you to save a script that reproduces the report to several destinations.

Save By-Group Script

Contains options that enable you to save a script that reproduces the platform report for all levels of a By variable to several destinations. Available only when a By variable is specified in the launch window.

Want more information? Have questions? Get answers in the JMP User Community (community.jmp.com).