The captioned X bar and R Charts table which specify the A2, d2, D1, D2, D3 and D4 constants for sample size n. These coefficients are used for process capability estimation and analysis. The control chart coefficient table are mostly used in production and manufacturing environment for controlling and monitoring the performance of machines.
| X bar and R Charts | ||||||
|---|---|---|---|---|---|---|
| Charts for Ranges (R) | Charts for Averages | |||||
| Divisor to Estimate σx | Factors for Control Limits | Control Limit Factor | ||||
| Subgroup Size n | d2 | D1 | D2 | D3 | D4 | A2 |
| 2 | 1.128 | 0 | 3.686 | 0 | 3.267 | 1.880 |
| 3 | 1.693 | 0 | 4.358 | 0 | 2.575 | 1.023 |
| 4 | 2.059 | 0 | 4.698 | 0 | 2.282 | 0.729 |
| 5 | 2.326 | 0 | 4.918 | 0 | 2.115 | 0.577 |
| 6 | 2.534 | 0 | 5.078 | 0 | 2.004 | 0.483 |
| 7 | 2.704 | 0.205 | 5.203 | 0.076 | 1.924 | 0.419 |
| 8 | 2.847 | 0.387 | 5.307 | 0.136 | 1.864 | 0.373 |
| 9 | 2.970 | 0.546 | 5.394 | 0.184 | 1.816 | 0.337 |
| 10 | 3.078 | 0.687 | 5.469 | 0.223 | 1.777 | 0.308 |
| 11 | 3.173 | 0.812 | 5.534 | 0.256 | 1.744 | 0.285 |
| 12 | 3.258 | 0.924 | 5.592 | 0.284 | 1.716 | 0.266 |
| 13 | 3.336 | 1.026 | 5.646 | 0.308 | 1.692 | 0.249 |
| 14 | 3.407 | 1.121 | 5.693 | 0.329 | 1.671 | 0.235 |
| 15 | 3.472 | 1.207 | 5.737 | 0.348 | 1.652 | 0.223 |
| 20 | 3.735 | 1.548 | 5.922 | 0.414 | 1.586 | 0.180 |
| 25 | 3.931 | 1.804 | 6.058 | 0.459 | 1.541 | 0.153 |
