CECIL RICE EXPORT, ALEXANDRIA, EGYPT

1. What control charts should be used to determine whether the process is in control or out of control?

We should use x-Charts and R-Charts to determine whether the process is in control or out of control. X-Charts are usually used when we know standard deviation of the sample. We calculate the upper and lower control limits based on that data. For this data, we assumed the standard deviation as 3 and we found the upper and lower limits for each day’s shifts.

According to Monday Shift 1 (00:00 to 08:00), the lower limit is 69.23 hence the numbers that are below 69.23, are becoming out of control. And the upper limit is 71.91, so the numbers which are above 71.91, become out of control due to assignable causes and not natural causes.

In addition, Tuesday Shift 1 (00:00 to 08:00), the lower limit is 68.54, thus the numbers which are below 68.54, are out of control. The upper limit is 71.22 and the numbers that are above 71.22, become out of control.

Finally, those processes which we calculated as upper and lower limits should be under control. In R-Charts, the important part is the upper and lower control limits and the specific mean. We calculated the upper and lower control limits for each day of shifts according to n is equal to four.

For instance, for Monday Shift 2 (08:00 to 16:00), the upper control limit is 4879 pounds and the lower control limit is 4865 pounds.

2. Develop a control charts for each shift. Does there appear to be a difference between the shifts?

We developed control charts for each shift three days. For Monday shift 1 from 00:00 to 08:00 the upper control limit is 71.91 and the lower control limit is 69.23. Shift 2 from 08:00 to 16:00, the upper control limit is 71.30 and the lower control limit is 68.25 and shift 3 from 16:00 to 00:00 the upper limit is 71.45 and the lower