The following data are for the throughput, as measured by the number of wafer lots produced per day by different operators (A, B, C, and D) on different machines (each operator used each machine on two different days): Eighty-four working days were needed to collect the data. The numbers in parentheses refer to the days on which the results were obtained. For example, on the first day, operator A produced 17 lots using machine 2, and on the 84th day, operator A produced 18 lots using machine 5. On some days (such as the third day), more than one item of data was collected, and on other days (such as day 40), no data was collected. Analyze the data, stating all assumptions and conclusions.

The following data are for the throughput, as measured by the number of wafer lots produced per day by different operators (A, B, C, and D) on different machines (each operator used each machine on two different days):

Eighty-four working days were needed to collect the data. The numbers in parentheses refer to the days on which the results were obtained. For example, on the first day, operator A produced 17 lots using machine 2, and on the 84th day, operator A produced 18 lots using machine 5. On some days (such as the third day), more than one item of data was collected, and on other days (such as day 40), no data was collected. Analyze the data, stating all assumptions and conclusions.