Hi David,
The "Shade Levels" option for the Capability Index Plot automatically shades the levels based on the Ppk slider on the right: Less than the slider value = red; up to 2x the slider value = yellow; more than 2x the slider value is green. This behavior can't be changed, but there's a workaround.
If you uncheck the "Shade Levels," then right-click on the Ppk axis and select Axis Settings..., you can create custom shaded zones to your liking. Example script below:
open ("$SAMPLE_DATA\Cities.jmp");
Process Capability(
Process Variables( :OZONE, :CO, :SO2, :NO ),
Spec Limits(
:OZONE( LSL( 0 ), Target( 0.05 ), USL( 0.1 ) ),
:CO( LSL( 5 ), Target( 10 ), USL( 20 ) ),
:SO2( LSL( 0 ), Target( 0.03 ), USL( 0.08 ) ),
:NO( LSL( 0 ), Target( 0.025 ), USL( 0.6 ) )
),
Moving Range Method( Average of Moving Ranges ),
Capability Box Plots( 0 ),
Goal Plot( 0, Shade Levels( 1 ) ),
Capability Index Plot( 1 ),
Process Performance Plot( 0 ),
SendToReport(
Dispatch(
{"Capability Index Plot"},
"2",
ScaleBox,
{Add Ref Line( {-1, 1}, "Solid", "Red", "", 1, 0.25 ),
Add Ref Line( {1, 1.33}, "Solid", "Yellow", "", 1, 0.25 ),
Add Ref Line( {1.33, 3}, "Solid", "Green", "", 1, 0.25 )}
)
)
);