Line Graphs

Prerequisites
Bar Charts

Learning Objectives

1. Create and interpret line graphs
2. Judge a line graph would be a appropriate for a given dataset

A line graph is a bar chart with the tops of the bars represented by points joined by lines (the rest of the bar is suppressed).

Line graphs are appropriate only when both the X- and Y-axes display ordered (rather than qualitative) variables. Although bar graphs can also be used in this situation, line graphs are generally better at comparing changes over time. Let us stress that it is misleading to use a line graph when the X-axis contains merely qualitative variables.