Determine the UCL for the Xbar chart of an Xbar R combined control chart given the following data
Rbar = .9
Xbar centerline = 4
s = .25
n = 5
Expert Answer
UCL = X bar central line + D4 x Rbar
Where D4 dependes on subgrup size (n) can be determined from standard table
here for n= 5 , D4= 2.114
UCL= 4 + 2.114 x 0.9 = 5.9