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In this blog, we will learn about the dumbbell chart:

1. What is a dumbbell chart?
2. When to use a dumbbell chart?
3. How to build a dumbbell chart in Tableau?

#### 1. What is a Dumbbell Chart

Dumbbell charts, also known as DNA charts, gap charts, barbell charts, and connected dot plots, are often used to illustrate the change between two data points. Dumbbell charts get their name from their appearance: with two circles, one on each end and a bar in the middle, resembling a dumbbell.

A Dumbbell Chart

#### 2. When to Use a Dumbbell Chart

Dumbbell charts are ideal for illustrating the change and comparing the distance between two data points across categorical data. It is often used to compare the change or growth of a measure from one year to another. The circles highlight the starting and end values, while the bars in the middle measure the size of the change. Dumbbell charts can be used as alternatives to line charts and side-by-side bar charts; personally, I feel that dumbbell charts can often be more visually appealing and potentially more engaging than its alternatives.

#### 3. How to Build a Dumbbell Chart in Tableau

We will use the Sample Superstore data to illustrate how to create a dumbbell chart.

##### Step 1: Plot Profit Against Each Sub-Category, and Filter to Show Only 2021 and 2022 Data
1. Drag [Profit] onto the Rows Shelf, and [Sub-Category] onto the Columns shelf.
2. Drag [Order Date] onto the Filters card, and select Year, and tick 2021 and 2022 only.

##### Step 2: Create a Duplicate Chart and Give it the Year Detail
1. Hold down the CTRL key, and left click and drag the SUM(Profit) pill to create a duplication of itself on the Rows shelf.
2. Drag [Order Date] onto the Detail card of any one of the charts.

##### Step 3: Create a Duplicate Chart and Give it the Year Detail
1. Change the mark type of the first chart to Circle, and the second chart to Line.
2. Drag [Order Date] onto the Path card of the line chart.

##### Step 4: Dual Axis and Synchronize Axis to Create the Dumbbell Chart
1. Click on one of the SUM(Profit) pills and select Dual Axis.
2. Click on one of the axis, and select Synchronize Axis.

You can see below, we have successfully created a Dumbbell Chart!

With additional customization and formatting, we can make our Dumbbell chart even more appealing and informative!

Practice makes perfect! If you are interested in learning more about dumbbell charts, I would highly encourage you to accept this challenge #WOW2022 Week 32: Can you build a dumbbell chart?

You can also find my solution here on Tableau Public, and feel free to download it and see if you can reverse engineer the chart!

Have fun!!!

##### Author: Martin Ding

Martin earned his Honours degree in Economics at the University of Melbourne in 2011. He has more than 7 years of experience in product development, both as an entrepreneur and as a project manager in robotics at an AI unicorn. Martin is expecting to receive his Master’s degree in Data Science from CU Boulder at the end of 2022. Martin is excited about data and it’s power to transform organizations. He witnessed at first hand of how instrumental data driven decision making (DDDM) was in leading to more team buy-in and insightful decisions. Martin joined the Data School to systematically enhance his knowledge of the tools, methodologies and know-how of Data Analytics and DDDM. When not working, Martin enjoys readings, cooking, traveling and golf. He also thoroughly interested in the practice of mindfulness and meditation.