Tableau is the most popular interactive data visualization tool, nowadays. It provides a wide variety of charts to explore your data easily and effectively. This series of guides - Tableau Playbook - will introduce all kinds of common charts in Tableau. And the next three guides will introduce the various Diverging Bar Charts.
In this guide, we will discuss the first of three types of diverging bar charts:
For each chart, we will learn in the following steps:
This guide (Part 1) will focus on the basic concepts and butterfly chart.
Diverging stacked bar charts are great for showing the spread of negative and positive values, such as Strongly Disagree to Strongly Agree (without a Neutral category) and because they align to each other around the midpoint, they handle some of the criticism of regular stacked bar charts, which is that it is difficult to compare the values of the categories in the middle of the stack.
The key point of a diverging stacked bar chart is comparing data with a midpoint or a baseline. Some bars expand toward the left, while others toward the right. Or, they grow up and down.
According to the scope of application, we can roughly classify mainstream diverging bar charts into three categories:
The left chart compares the health condition of males and females. The right chart compares the characteristics of ideal women and real women.
The butterfly chart is also called a tornado chart. The names come from the shape of the chart. It compares two associated measures side by side. The butterfly chart gives a quick glance view of the difference between two groups with the same parameters.
In the above dataset, we will use a butterfly chart to compare the time trend of birth rates between 20-25 and 30-35 year old mothers. Let's draw a standard butterfly chart first:
IF [Age Start] == 20 THEN [Birth Rate] END-> name it as "Birth Rate of Age 20-25". The same for the second field. Only change to
0in the formula.
A raw butterfly chart is completed. We can see the middle margin is too broad, but we are not able to change just the middle width. In the next section, we will learn two ways to solve this problem.
To shrink the middle margin, we can use a dashboard to concatenate instead of a single worksheet.
Alternatively, we can leave no space in the center at all and display the label on the bar, inspired by XY Data - Darren:
Here is the final chart with no margin version:
From the horizontal comparison, birth rates of 20-25 age are much higher than 30-35 age. As an exception, they are very close since 2000, even opposite after 2010. The reason is probably that today's society is more inclined to late marriage and late childbearing.
From the vertical comparison, years between 1945-1965 get the highest birth rates for both age groups. After World War II, the United States advocated more births for recovery and development. Birth rates of age 20-25 are continuously declining since 1955. By contrast, birth rates of 30-35 age have kept growing since 1975. Maybe it's because more and more young people tend to marry later.
In this guide, we have learned about a variation of a bar chart in Tableau - the diverging bar chart.
We introduced the characteristics and usage scopes of various diverging bar charts. We mainly focused on Butterfly Chart in this part. First, we learned the standard process, then we optimized it with dashboard and dual axis.
In the second part, we will cover another common type: Standalone Diverging Bar Chart.
In the third part, we will cover the last type: Diverging Stacked Bar Chart.
You can download this example workbook Bar Chart and Variations from Tableau Public.
In conclusion, I have drawn a mind map to help you organize and review the knowledge in this guide.
I hope you enjoyed it. If you have any questions, you’re welcome to contact me [email protected].