An integrated circuit is connected to its frame by five wires. Twenty-five samples of eight units were taken and the pull strength of one wire was measured. The data are in the accompanying file.
| Sample |
Xbar |
R |
s |
| 1 |
9.99 |
0.28 |
0.09 |
| 2 |
10.02 |
0.43 |
0.13 |
| 3 |
10.1 |
0.16 |
0.05 |
| 4 |
9.9 |
0.26 |
0.09 |
| 5 |
9.92 |
0.22 |
0.07 |
| 6 |
10.05 |
0.4 |
0.15 |
| 7 |
9.97 |
0.08 |
0.03 |
| 8 |
9.93 |
0.48 |
0.15 |
| 9 |
10.01 |
0.25 |
0.09 |
| 10 |
9.87 |
0.29 |
0.1 |
| 11 |
9.9 |
0.39 |
0.14 |
| 12 |
9.97 |
0.27 |
0.08 |
| 13 |
10.02 |
0.2 |
0.07 |
| 14 |
9.99 |
0.37 |
0.13 |
| 15 |
9.99 |
0.2 |
0.06 |
| 16 |
10.04 |
0.26 |
0.09 |
| 17 |
10.07 |
0.23 |
0.07 |
| 18 |
10.04 |
0.35 |
0.12 |
| 19 |
9.95 |
0.25 |
0.09 |
| 20 |
9.98 |
0.15 |
0.06 |
| 21 |
9.98 |
0.3 |
0.1 |
| 22 |
10.02 |
0.14 |
0.06 |
| 23 |
9.94 |
0.24 |
0.07 |
| 24 |
10.04 |
0.13 |
0.04 |
| 25 |
10.04 |
0.24 |
0.07 |
(a) Compute the 3? limits for the R chart. Is the variance out of control
(b) On the basis of the Western Electric rules, is the process mean in control? If not, when is it first detected to be out of control?