See attached data file.
A branch manager of a brokerage company is concerned with the number of undesirable trades made by her sales staff. A trade is considered undesirable if there is an error on the trade ticket. Trades with errors are concealed and resubmitted. The cost of correcting errors is billed to the brokerage company. The branch manager wants to know whether the proportion of undesirable trades is in a state of statistical control so she can plan the next step in a quality improvement process. Data was collected for a 30-day period with the results attached.
A) Construct a control chart for these data.
B) Is the process in control?
C) Based on a and b what should the manager do to improve the process?