The manager of the injection molding department has asked you to make a EWMA chart for a maintenance operation-weekly mold changes. The table of data below shows the number of mold changes for the last 45 weeks. Construct EWMA charts using r = 0.33.
Identify any statistical signals on the charts or other trend like patterns.
What can you report to the manager about the mold-changing process?
Make sure your report includes the following:
- estimates of the process mean and standard deviation,
- exponentially weighted moving averages,
- control limits and centerlines,
- EWMA Control Charts,
- and comments to the manager.