INDEX VALUE PLOT

http://wattsupwiththat.com/2009/08/17/evidence-that-ocean-net-heat-flow-is-connected-with-climate-shifts-co2-not-correlated/

Index value plots take some form of an index value and plot it. This is different from a line graph that uses an absolute value. The above index plot shows the value over the given time frame of the Pacific Decadal Oscillation.