topic Control chart spec limits bug in Discussions

Control chart spec limits bug

dm — Mon, 03 Apr 2017 19:46:20 GMT

When you use the "control chart builder" on a column which has spec limits, those limits are plotted on both the Individual and Moving Range charts. It's useful to have the limits shown on the Individual chart, but they make no sense on the Moving Range chart and make the axis range useless.

Here's an example using data from the "Abrasion" sample data set (adding spec limits to the column before running control chart builder):

It's sometimes possible to remove the limits after the chart is created, but sometimes they reappear.

Also, I need to do this from a script--it's been difficult to determine how to access them.

Here's a script which starts with the sample data "Abrasion" already open (and spec limits added to the column "Abrasion"):

dt = Data Table("Abrasion");

dt << Control Chart Builder(
	Show Control Panel(0),
	Variables(X(Column("Date/Time")), Y(:Abrasion)
	)
);

Does anyone know what to add to this script to remove the undesired LSL/Target/USL lines from the Moving Range chart?

Re: Control chart spec limits bug

tonya_mauldin — Mon, 03 Apr 2017 20:18:10 GMT

This is a known issue detailed in the following note. http://www.jmp.com/support/notes/59/378.html

This happens when you have Show as Graph Reference Lines checked in the column property. You can uncheck that in the column property either through the GUI or through JSL. To see the JSL syntax, use the Scripting Index.

If you wish to still have this checked, you can use the Remove Ref Line command to remove the reference lines from the graph. You can do this through the GUI or through JSL. To see the syntax, use the Scripting Index.

Re: Control chart spec limits bug

dm — Mon, 03 Apr 2017 20:48:35 GMT

Thanks!

Here's what the script looks like (note that you can use text names of ref lines instead of their values--not sure if this is documented anywhere):

dt = Data Table("Abrasion");

mycc = dt << Control Chart Builder(
	Show Control Panel(0),
	Variables(X(Column("Date/Time")), Y(:Abrasion)
	)
);

rmycc = mycc << report;
axisbox = rmycc[axis box(3)];
axisbox<<Remove Ref Line("LSL");
axisbox<<Remove Ref Line("Target");
axisbox<<Remove Ref Line("USL");