Median & Range Chart
Median and Range Control Chart

The Median and Range chart provides a graph of the median of a process characteristic and the range extent. The Median chart provides a picture of how well a process is centered using the median or middle value. The median of a subgroup is the center value where, half of the observed values are above it and half are below it. An important distinction between the median of a set of values and the average is that the median is influenced less by outliers than is the average. This can be an advantage or a disadvantage depending on your objective.