Moving Range Chart UCL calculation in JMP8
The Moving Range UCL calculation is given in text books as UCL=D4(MRavg) with D4=3.267. When I set the JMP control chart IR at 3 Ksigma the UCL for the MR agrees with the calculation above. When I set the JMP control chart IR at 3.5 Ksigma I get a different UCL for the Moving Range chart. I understand the manual calculation for the accompanying Individuals Chart for 3.5 Ksigma (UCL=Xavg +/-3.5xMR...