listed. Being evaluated. Samples of five observations each have been taken, and the results are as SAMPLE 2 79.2 80.5 79.6 3 5 6 78.9 80.5 79.7 78.8 78.7 79.6 79.4 79.6 80.6 80.0 81.0 80.4 79.7 80.4 80.5 78.4 80.4 80.3 79.4 80.8 80.0 81.0 80.1 80.8 80.6 78.8 81.1 Click here for the Excel Data File Factors for three-sigma control limits for X and R charts FACTORS FOR R CHARTS Number of Lower Observations Factor for Upper Control Control in Subgroup, Chart, Limit, A2 Limit, n 03 04 2 1.88 3.27 3 1.02 2.57 4 0.73 2.28 5 0.58 0 2.11 6 0.48 0 2.00 7 0.42 0.08 1.92 8 0.37 0.14 1.86 9 0.34 0.18 1.82 10 0.31 0.22 1.78 11 0.29 0.26 1.74 12 0.27 0.28 1.72 13 0.25 0.31 1.69 14 0.24 0.33 1.67 15 0.22 0.35 1.65 16 0.21 0.36 1.64 17 0.20 0.38 1.62 18 0.19 0.39 1.61 19 0.19 0.40 1.60 20 0.18 0.41 1.59