What tool was developed by Shewhart to monitor processes and determine changes?

Control charts were developed by Walter A. Shewhart as a statistical tool to monitor processes over time and identify any variations in the process. These charts plot data points of a process on a graph, with upper and lower control limits set to determine acceptable variation. They allow practitioners to distinguish between common cause variation, which is inherent to the process, and special cause variation, which indicates a change or an issue in the process. This ability to identify when a process is going out of control makes control charts an essential tool in quality management and process improvement methodologies like Six Sigma.

In contrast, flowcharts are used to visualize processes, histograms display the distribution of a dataset, and scatter plots analyze the relationship between two variables, but none of these serve the specific purpose of monitoring variations in processes over time as effectively as control charts do.