Creating Nolan Charts in Tableau

I have been following the 2020 US election very closely, yes, it is still in the primary season, but I saw a Nolan Chart and thought that I had to create this in Tableau. So found this quite interesting, so hopefully, you will do as well.

Data

We will start by loading the following data into Tableau Desktop / Tableau Public.

This information has been collated from the On The Issues website, where they have tracked the positions of politicians and given it a score. You can read more about this here: https://www.ontheissues.org

Calculated Fields

With our data set loaded into Tableau, we are going to create the following Calculated Fields:

Hypotenuse

SQRT(SQUARE([Social Issues Score])+SQUARE([Economic Issues Score]))

Yes, we get to use the Pythagorean theorem, I did not think I would ever have a need to use this.

Angle (Degrees)

DEGREES(ACOS(ZN([Economic Issues Score])/ZN([Hypotenuse])))

Angle (Degree+45)

ZN([Angle (Degrees)]+45)

Note: We are going to rotate the angle of the point by 45 degrees (we can make this dynamic, but for a Nolan Chart, 45 degrees is what we are looking for).

X

COS(RADIANS([Angle (Degree+45)]))*[Hypotenuse]

Y

(SIN(RADIANS([Angle (Degree+45)]))*[Hypotenuse])-70.7

Note: We subtract 70.7 to move the centre point to zero. For me, it just makes things a bit neater.

With this done, let us start creating our data visualisation.

Worksheet

We will now build our worksheet:

• Change the Mark Type to Circle
• Drag Politician to the Detail Mark
• Drag X onto the Column Shelf
• Drag Y onto the Rows Shelf
• Drag Social Issue Score onto the Color Mark
  • Click on the Color Mark and select Edit Color
  • Set Palette to Red-Blue Diverging
  • Set Stepped Color to 2
  • Click on Advanced and set Centre to 50

If all goes well, you should now see the following:

Now I want you to download the following background image:

This was created using a combination of Excel and GIMP, but we can use this forevermore. With the file downloaded, we will not apply this.

• In the menu go to Map, Background Images and then select your data source.
• Click on Add Image…
• In File or URL browse to the nolan-chart-background
• In X Field select X
  • Make sure X is selected
  • Set Left to -75
  • Set Right to 75
• In Y Field select Y
  • Make sure Y is selected
  • Set Left to -75
  • Set Right to 76
• Set the Washout to 50%
• Click Ok

You should now see the following:

With this, we now have our Data Visualisation functionally built. So now we will work on cosmetics:

• Fix the Y-Axis to be from -90 to 90
• Fix the X-Axis to be from -90 to 90
• Hide the X and Y-Axis Headers
• Remove all Grid Lines
• Remove all Zero Lines
• Edit the Tooltips

You should now want to end up with the following:

and boom, we are done! I hope you enjoyed creating this data visualization and learned some cool techniques as well. As always, you can find this data visualisation on Tableau Public at https://public.tableau.com/profile/toan.hoang#!/vizhome/NolanChart/NolanCharts

Summary

I hope you all enjoyed this article as much as I enjoyed writing it and as always do share the love. Do let me know if you experienced any issues recreating this Visualization, and as always, please leave a comment below or reach out to me on Twitter @Tableau_Magic. Do also remember to tag me in your work if you use this tutorial.

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• Creating Bespoke Data Visualizations (Udemy)
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• Advanced Calculations (Online Instructor-Led)
• Creating Bespoke Data Visualizations (Online Instructor-Led)