An X-bar chart is a type of control chart that is used to determine the average value of a group of units. It is also known as a mean chart. It plots the sample means of subgroups of units over time and compares them with the center line and the control limits. An X-bar chart is useful for monitoring the central tendency of a process and detecting any shifts or trends in the process mean. It is often used in conjunction with an R-chart, which measures the subgroup variation. References:
Managing Supply Chain Operations, Chapter 9: Quality Management, Section 9.2: Statistical Process Control, Subsection 9.2.1: Control Charts CPIM Exam Content Manual, Module 8: Quality, Technology and Continuous Improvement, Section
8.1: Quality Management, Subsection 8.1.2: Statistical Process Control, Subsubsection 8.1.2.1: Control Charts