The purpose of control charts is to:

a. determine if the measurement is variable or attribute.
b. weed out defective items.
c. distinguish between random variation and assignable variation in the process.
d. determine the root cause of the problem. provide meaningful work for quality inspectors.

D. determine the root cause of the problem. provide meaningful work for quality inspectors.

Explanation:

The control chart is a graph used to study how a process changes over time. Data are plotted in time order. A control chart always has a central line for the average, an upper line for the upper control limit, and a lower line for the lower control limit. These lines are determined from historical data.

Allow operators to control the process. Improve process control to give less variation in the output, lower the unit cost, and increase the processing capacity. Provide a common language for all staff to discuss and improve processes. Control charts are not a substitute for action.

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