Presentation of Data in Figures

Presentation of results in figures can be a very powerful way to communicate information. Figures must be done correctly to be effective. Two general categories of graphic presentation of data are: x-y graphs and bar graphs.

• show trends and patterns over an interval, data points have some clear relationship to each other
• horizontal axis (x-axis or abscissa) is used for the independent variable
• vertical axis (y-axis or ordinate) is used for the dependent variable (depends on values of x)
• used to present the results of regression analysis
• connect data points to show trends, do not extend lines beyond the data
• can be used to show frequency distributions

• data represented by a bar, only one axis (y-axis usually)
• no relation between categories other than an interest in comparing effects in an experiment
• can be used for a frequency distribution where the area of the bar is proportional to the size of the value represented

Effective graphs have the following characteristics:

• axes are labeled with name and units of variables
• the graph is framed on four sides
• tick marks should be shown on at least the bottom and left side
• all the data points should be within the frame and no points should fall on the frame
• all lettering should be legible