Understanding and using Line Charts
How do I read a Line Chart?
For most line charts, the horizontal axis represents a dimension of time, while the vertical axis represents a quantitative value (Ex. money, number of people, percent change, etc.). The graph should have each axis, or horizontal and vertical lines framing the chart, labeled. Line charts can display both single or many lines on a chart. The use of a single line or many lines depends on the type of analysis the chart should support. A line chart with many lines allows for comparisons between categories within the chosen field.
With a single line, the shape and direction of the line provides the means to identify changes and trends within the data. A line rising in height as it moves from the left to the right side of the chart indicates an increasing trend. The opposite, a line decreasing in height, indicates that the line has a downward trend.
Many lines allow for comparison across different members within the same field as well as where lines intersect. When a field has several members, different colors are often used to make it possible to distinguish between members on the chart. It is also important to remember that charts with fewer lines are easier to read. So, be thoughtful when choosing the type of chart to best represent your data. Too many categories will clutter the line chart and make it harder to understand.
This line chart, known as a category line chart, splits the number of borrowers into gender, so two lines are displayed across the course of several years.
- It uses a strong color to highlight the line for the category being focused on
- It uses a neutral color for the second line
- Label colors match the lines for ease of identification
- The chart is not cluttered with labels