3. Reading & Interpreting Graphs and Charts

3.3. Line Graphs

As with bar graphs, line graphs offer an effective way of visually depicting a relationship between a set of two or more variables (for example, amount and type) and this relationship is reflected in the comparative steepness (or gentleness) of the lines gradient:

line graph

The range of variables that can be accommodated for in a line graph is clearly an advantage that this type of chart has over others, but when the data you are dealing with does not display any trend or pattern (for example, if it deals with proportionate amounts, rather than an increase or decrease over time) then here you would be better off using a pie chart.