A stacked bar chart is a variant of the bar chart. While a classic bar chart allows you to compare data points to each other, a stacked bar chart is a little different.
Parts of the data may be adjacent if the bands are horizontal or stacked if the bands are vertical. Each bar represents a total value, divided into several sub-values.
On each bar, the equivalent sub-sections are presented in the same color. This format is very useful to easily compare both the bars with each other and the components of each bar. This type of graph allows you to identify changes in a data series and when these changes occurred.
To read a stacked bar graph correctly, it is important to understand how the information is presented. Segments of the same color can be compared to each other. If the diagram is horizontal, the vertical axis represents the variable and the horizontal axis shows the different segments.
Stacked bar charts are suitable for several types of data visualization. They are ideal for nominal comparisons, to understand a change between two time periods, or to compare a part with a set.
This type of graph is also suitable for understanding the distribution of different items, or for comparing them over time. Similarly, they are suitable for breaking down the results of a study by demographic groups.
A stacked bar chart also allows you to visualize changes over time on a recurring set such as objects produced by a factory. Finally, it also allows you to establish rankings to verify how a group of results accumulates over time.
However, there are also cases where stacked bar charts are not suitable.
There are several tips for improving a stacked bar chart to make it easier to read. These include grouping the data together for greater visibility or changing the axes by changing the scale. Titles and legends for each axis can also clarify the message.