Index value plot

Index value plots are graphical representation that are used to display the frequency with which a certain event either increases or decreases. These plots are used a lot by those who are following a certain stock or weather patterns. These can also be used by biologist who are monitoring breeding populations of a specific set of animals. The index value plot below shows the average stream flow index since 1999.

Link: http://mapanalysisnoles949.blogspot.com/2008/06/index-value-plot.html