7. The quality manager of a company wishes to analyze the data that is coming to him in the form of a list of defects that have occurred in the shipping department. The report comes with defects listed chronologically as they occurred, the cost of the repair necessary to correct each defect, the person involved, and a description of the defect. The manager would like to determine which of the defects should be corrected first according to the frequency of the defect occurring. He should use which of the following quality tools?