Question: Suppose the specification limits of particular dimension are 10mm and 12mm. lf the distribution of the current process is assumed to be normal with a mean of 11.3 mm and a standard deviation of 0.5 mm, how many parts per million defective (ppm) would be expected?
If the process described above could be centered, how many ppm defective could then be expected?
Suppose that, instead of centering the process, the standard deviation could be reduced to 0.3mm. How many ppm defective would be expected?
Based on the above results, which parameter is more important to control?
A. Process center
B. Process variation