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X-Bar & R Charts are Control Charts designed for tracking the average of sub-grouped continuous data. They consist of two separate charts;  “X-Bar” stands for the “Average” Chart which tracks the mean of sub-groups of up to 6 data points and “R” stands for “Range” Chart which tracks the difference between the maximum and minimum values in the subgroup. These charts are not as sensitive to non-normal data as the I & MR Charts.

A classic example of an X-Bar & R Chart is to track the average cycle time to deliver packages by sampling 5 packages per day.

For a better understanding of the X-Bar & R Chart, check out our Black Belt Training & Certification Course!

Elisabeth Swan

Elisabeth is a Managing Partner at For over 25 years, she's helped leading organizations like Amazon, Charles Schwab and Starwood Hotels & Resorts build problem-solving muscles with Lean Six Sigma to achieve their goals.

Tracy O'Rourke

Tracy is a Managing Partner at She is also a Lean Six Sigma Green Belt Instructor at UC San Diego and teaches in San Diego State University’s Lean Enterprise Program. For almost 20 years, she has helped leading organizations like Washington State, Charles Schwab and GE build problem-solving muscles.