How to Build a Barbell Chart with Tableau
Step 1:
Drag [Quantity] to columns, [Category] to rows, and [Sub-category] to rows. This will create a bar chart.

Step 2:
Add Year([Date]) to the detail shelf, and filter out 2017 and 2018.

Step 3:
Change the mark type to circle, and copy year to color. You’ll see the barbells displayed without a line in between.

Step 4:
Copy the [Quantity] pill to create a second axis.

Step 5:
Change the mark type to line, and move year to the path shelf.

Step 6:
Create a dual axis, and you have a barbell chart.
