What is the purpose of an area graph?

An area chart is a specialized form of a line chart where, instead of simply connecting the data points with a solid line, we also fill the area underneath that line with a solid color. This may seem like a small change, but it has a major impact on how we perceive the data in the chart.

Area plots can be effective for:

• The rise and fall rates of various data series over time;
• Transfers of total amounts over time, as well as some breakdowns (but only up to a certain point);
• Emphasizing the relationship of a part to a whole over time, when one part is very large or changes from very large to very small;
• Displaying changes over time on separate panels of a small multiple graph.

Area charts are not  an ideal choice for:

• Data sets at scales that have no significant relationship to zero;
• Displaying multiple changing data sets over time;
• Indicators of differences in values.

In this article, we’ll talk about how an area graph works  specific database by industry and some issues to consider when considering creating one.

How does an area graph work?

Area graphs look the same as regular line graphs, with two exceptions:

1. The space between the X-axis and each line on the graph is filled with some color (possibly a different shade or opaque, depending on the designer’s preference).
2. The X-axis MUST BE ZERO.

Take a look at a chart of US music sales 10 micro habits that will help change your life over time, broken down by format:

 

When we look at line graphs, we focus on how the values ​​on the vertical axis are changing: up or down, etc. By their nature, line graphs are better at showing how values ​​are changing over time than the exact amount at each measured point.

However, our perception changes when the chart creator adds a color fill between the line and the baseline, turning our line graph into an area graph.

 

Instead of seeing lines, we see each data series as a polygon shape; and we evaluate each data series less by how it changes over time and more by how we perceive the overall color area.

For this reason, we cannot use scales on area graphs that do not have a meaningful relationship to zero. As with histograms, we must use a zero baseline.