How do I read a graph and why is this important?

A graph allows us to identify how and if the variables of an experiment are correlated. If correlation is seen, this implies a causal relation between the two variables. This correlation may be positive (if x increases, y increases), negative (if x increases, y decreases) or there may be no correlation. It is therefore important to quickly identify the dependent versus independent variables on a graph. Typically, the independent variable name will be on the horizontal (x) axis, with the dependent variable name labelling the vertical (y) axis. Thus, the dependent variable is plotted versus the independent variable name. This information should be easily identifiable on a well-formatted graph.

Sometimes, we may see results that are time dependent. Over a short timescale, no relation between the dependent and independent variable is clear. However, when the measurement is taken repeatedly, a cyclical or other trend may become apparent. For example, we can see how the number of sunspots varies over an 11-year cycle.

Interpreting a graph

Click on the regions of the graph to learn more about them.