A chart used to monitor the stability of a process over time is called a:

• A. Control Chart
• B. Histogram
• C. Scatter Diagram
• D. Flow Chart

Answer: (A)

A control chart helps you watch a process as it runs to see if it stays stable over time. It plots measurements in the order they’re taken and includes a central line for the average and upper and lower control limits that reflect expected random variation. If the process is in control, data points scatter around the center and mostly stay within the limits without nonrandom patterns. Signals like points outside the limits or recognizable patterns (runs, trends, cycles) indicate assignable causes that may require investigation and adjustment. This time-ordered view is what makes it the right tool for assessing stability. Histograms show how data are distributed, not how they change over time; scatter diagrams show relationships between two variables; flow charts map the steps in a process.