What type of chart is used to track process performance over time?

A control chart is specifically designed to monitor and analyze process performance over time. It provides a visual representation of how a process behaves, showcasing variations that occur during the process. Control charts help in identifying trends, shifts, and any signals that suggest the process is going out of control. By plotting data points over time, control charts allow teams to detect variations that could indicate potential issues in the process that need attention.

This type of chart is essential in Six Sigma and quality improvement efforts because it emphasizes stability and capability of the process. By observing how the data points fall within control limits, teams can make informed decisions on process adjustments or improvements.

In contrast, other types of charts such as bar charts and pie charts serve different purposes. Bar charts are typically used for comparing quantities across different categories, while pie charts show proportions of a whole. Line graphs can track changes over time similarly to control charts, but they do not inherently include the control limits that are crucial for assessing process stability and performance. Thus, the control chart is the most appropriate choice for tracking process performance over time.