Interpreting a Box Whisker Chart

Each Box-Whisker represents the mean (average) and variation of the specified Characteristics. The edges of the Box are customarily defined at ±1 sample standard deviations , with the Whiskers extending to ±3 sample standard deviations.

As an enumerative statistical tool, care should be taken in its interpretation. Unless statistical control of the underlying process is established, the statistics presented on the Box-Whisker may not be reflective of the expected process outcome.

See also:

When to Use a Box Whisker Chart

Box Whisker Chart Calculations

Learn more about the Quality Improvement principles and tools for process excellence in Six Sigma Demystified (2011, McGraw-Hill) by Paul Keller, or his online Green Belt certification course ($499).