A graph is a pictorial representation of information recorded in a data table where the independent variable with units are located on the X or horizontal axis and the dependent variable with units are located on the Y or vertical axis.  A graph is used to show relationships between two or more different factors. Always use a descriptive title for the graph (how the independent variable affects the dependent variable). It may be the same as the title of the data table.

A bar graph shows a quantitative comparison between ordered pairs, using a series of columns to display data.  Usually, the independent variable is all text; it is not a measurement and therefore will not have a unit. Look at the following data table and graph.

Multiple bar graphs are used when the dependent variable has more than one group or category. A key or legend should be used to show how the two groups are represented.

A line graph shows a continuous relationship (trend) between two variables. Ordered pairs are plotted as points and then connected.  Line graphs display all numerical data because both independent and dependent variables are measurements. Look at the following data table and graph.

Multiple line graphs are used when the dependent variable has more than one group or category. A key or legend should be used to show how the two groups are represented.

A pie graph shows how portions make up a whole such as percentages with the entire circle representing 100%.