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.