GRAPHS

Graphs are valuable for showing relationships between variables. We can also use them to show trends, cycles, cumulative changes, and distributions.

Normally, we plot graphs on grid lines using a horizontal, or x-axis, and a vertical, or y-axis. The grid lines show the numerical scales along each axis. However, with the advent of computer-printed graphs, the use of grid lines has become optional.

Line/coordinate graphs and logarithmic graphs are the most common type of graphs.

Example

Tips for Making Graphs Use accurate captions to identify the content and purpose of the graph Ensure that scales accurately reflect the data being presented Place tick marks at appropriate intervals

• Use multiple lines to show the relationship between three or more variables, with different line patterns to depict different variables
  
  

• Orient all labels, numbers, and letters so they are parallel with the horizontal axis

Scales should increase from bottom to top along the y-axis and from left to right along the x-axis. We should establish scale minimums and maximums at the end of each axis, placing scale labels at appropriate intervals to aid in data interpretation.

We must keep graphs simple by eliminating anything that does not contribute to the central visual message. We should not use more labels, numbers, tick marks, or grid lines than necessary to clearly communicate the data relationships.

The inclusion of an informative caption helps our readers quickly interpret the information presented in the graph.