Sum Mean Value Range x1 x2 x3 x4 x5 x6 x7 x8 R 50 49 51 50 50 48 50 47 52 51 47 49 51 52 49 50 52 48 50 49 53 50 51 47 51 51 49 48 51 47 50 51 53 51 52 50 52 47 48 52 50 49 47 49 50 51 47 48 50 50 51 50 51 52 50 52 53 48 50 48 52 49 47 50 48 49 53 51 49 50 52 51 n k double bar R-bar UCL x LCL R-bar UCL R-bar LCL Number of Data Points Factors for X-Charts in Subgroup Factors for R-Charts LCL UCL (n) A2 D3 DA 2 1.88 0 3.27 3 1.02 2.57 4 0.73 2.28 5 0.58 2.11 66819 0.48 2.00 0.42 0.08 1.92 0.37 0.14 1.86 0.34 0.18 1.82 10 0.31 0.22 1.78 11 0.29 0.26 1.74 261842 0.27 0.28 1.72 13 0.25 0.31 1.69 0.24 0.33 1.67 15 0.22 0.35 1.65 0.21 0.36 1.64 17 0.20 0.38 1.62 0.19 0.39 1.61 19 0.19 0.40 1.60 20 0.18 0.41 1.59