The major reason for using a control chart is to:

The major reason for using a control chart is to:

• A. Detect non-random variation.
• B. Determine a cause-effect relationship between two or more variables
• C. Predict future demand
• D. Compare two samples for differences

Answer: (A)

Control charts are used to monitor a process over time and separate the normal, inherent variation (common cause) from unusual, identifiable changes (special or assignable causes). The main purpose is to detect non-random variation so you can investigate and address the specific source causing it. When data stay within control limits and show only random patterns, the process is considered in control. If a point falls outside the limits or shows a non-random pattern like a trend or run, it signals an assignable cause that deserves attention. The other options describe activities not served by control charts: forecasting future demand, testing differences between samples, or establishing cause-effect relationships, whereas control charts focus on identifying when the process is no longer statistically in control due to non-random variation.

Control charts are used to monitor a process over time and separate the normal, inherent variation (common cause) from unusual, identifiable changes (special or assignable causes). The main purpose is to detect non-random variation so you can investigate and address the specific source causing it. When data stay within control limits and show only random patterns, the process is considered in control. If a point falls outside the limits or shows a non-random pattern like a trend or run, it signals an assignable cause that deserves attention. The other options describe activities not served by control charts: forecasting future demand, testing differences between samples, or establishing cause-effect relationships, whereas control charts focus on identifying when the process is no longer statistically in control due to non-random variation.