The independent variable on a graph is the variable that stands alone and isnt changed by the other variables being measured. It is the variable that is being manipulated or changed by the experimenter. For example, in a graph showing the amount of rainfall that occurs at different times of year, time of year would be the independent variable because it does not depend on rainfall. On a graph, the independent variable is plotted on the x-axis (horizontal line) and the dependent variable is plotted on the y-axis (vertical line) .