In: Statistics and Probability
Results from the last four samples from a process are shown in the table. Calculate control limits for an R and X chart. Determine whether the process is in statistical control.
Sample number |
Observation 1 |
Observation 2 |
Observation 3 |
Observation 4 |
1 |
5 |
5.01 |
4.9 |
5 |
2 |
5.01 |
5.02 |
4.98 |
5 |
3 |
5.02 |
5.07 |
4.99 |
4.98 |
4 |
4.9 |
4.92 |
5.01 |
5.23 |
To control the lead time of a process, samples of size ten are taken from the process. If the average time to complete the process is three days, with a standard deviation of 0.5 days. Calculate the control limits for an X chart at 3 sigma level.