What is a graph?
A graph is a way of presenting data visually so that information is easy to read and compare. Three kinds of graph commonly used in Geography are the bar graph, the line graph and the pictograph.
Types of graph and their uses
- Bar graph — uses bars of equal width to compare quantities across several categories, such as the population of a few states.
- Line graph — joins points with a line to show continuous change over time, such as monthly temperature in a year.
- Pictograph — uses symbols or pictures to represent values; each symbol stands for a fixed value shown in the key.
Key idea
A bar graph compares categories, a line graph shows change over time, and a pictograph uses symbols whose value is explained in the key.
Constructing a graph correctly
Every graph must have a clear title so the reader understands what is shown. The horizontal axis is called the x-axis and the vertical axis is called the y-axis. The scale on each axis must be even so that the data is not misleading. In a bar graph, all bars are drawn with equal width and equal gaps between them. In a pictograph, the key explains the value of each symbol. A complete graph with a title, axis labels and a correct scale lets us interpret information quickly and accurately.