1.2 Time series line graphs
In time series line graphs, data are plotted or organised along a time dimension. Time series graphs are used for displaying data that show cyclical fluctuations or changes, such as growth, over time. Suppose that you wanted to present the data shown in Table 2 as a graph.
Table 2: Number of staff in an organisation
You would plot the data in a line graph like the one shown in Figure 2.
As a rule, the variable plotted on the horizontal (x) axis is the interval of time, for example years, months or minutes. This rule leads to the use of ‘time series’ to describe this kind of chart. The other variable, in this instance ‘Number of staff’, is plotted on the vertical (y) axis. The points are then joined up to form a continuous line, which shows how staff numbers have changed in the organisation over the years.