What does a control chart specifically help in monitoring?

A control chart is a fundamental tool used in statistical quality control to monitor the performance of a process over time. It specifically assists in observing process stability and variations in test results by displaying data points and control limits on a graph.

The control chart enables practitioners to differentiate between common variations, which are expected and inherent to the process, and special variations, which may indicate potential issues that need to be addressed. By regularly analyzing the data plotted on the chart, one can assess whether the test results are consistently within the predetermined limits, helping to maintain quality and consistency in non-destructive testing (NDT) practices. This monitoring is crucial for ensuring that processes remain under control and produce reliable outcomes.

Other options, while they pertain to aspects of quality assurance and testing, do not capture the specific focus of a control chart in monitoring the trends and variations in process characteristics directly related to the testing outcomes.