The following table describes the factors for standard deviation control limits in the Statistical Data block.
|
Subgroup Size |
B3 |
B4 |
|
2 |
0 |
3.267 |
|
3 |
0 |
2.568 |
|
4 |
0 |
2.266 |
|
5 |
0 |
2.089 |
|
6 |
0.030 |
1.970 |
|
7 |
0.118 |
1.882 |
|
8 |
0.185 |
1.815 |
|
9 |
0.239 |
1.761 |
|
10 |
0.284 |
1.716 |
|
11 |
0.321 |
1.679 |
|
12 |
0.354 |
1.646 |
|
13 |
0.382 |
1.618 |
|
14 |
0.406 |
1.594 |
|
15 |
0.428 |
1.572 |
|
16 |
0.448 |
1.552 |
|
17 |
0.466 |
1.534 |
|
18 |
0.482 |
1.518 |
|
19 |
0.497 |
1.503 |
|
20 |
0.510 |
1.490 |
|
21 |
0.523 |
1.477 |
|
22 |
0.534 |
1.466 |
|
23 |
0.545 |
1.455 |
|
24 |
0.555 |
1.445 |
|
25 |
0.565 |
1.435 |
Reprinted, with permission, from the Manual on the Presentation of Data and Control Chart Analysis, copyright © American Society for Testing and Materials, 1990.
