Dataskera

Tornado Chart

Two opposed bars per category around a shared centre. Sorted by how far the pair reaches it takes the funnel shape that gives the chart its name and answers a sensitivity question: which drivers move the number most. Left in data order with age bands on the category shelf, the same drawing is a population pyramid.

Data Requirements

Your Tableau worksheet should include:

  • 1 Dimension for the Category encoding. One opposed pair per value.
  • 1 Dimension for the Side encoding. The two values being compared: low and high, men and women, before and after.
  • 1 Measure for the Value encoding. How far each bar reaches.

Add Tornado Chart to your worksheet

First, download the manifest file. It tells Tableau where to load the extension from.

Download tornadochart.trex

Direct link: https://dataskera.com/downloads/tornadochart.trex

Then, in Tableau:

  1. On the Marks card, open the Mark type dropdown, and under Viz Extensions choose Add Extension.
  2. In the Add an Extension dialog, choose Access Local Viz Extensions, then open the tornadochart.trex file you just downloaded.
  3. When Tableau asks, allow the extension to access the data in the workbook.
  4. The welcome screen appears. Sign in with your Dataskera account, or on Tableau Desktop choose Use on Desktop without an account. See Signing in & access below.
  5. Build the chart: drag a dimension onto Category, the two-value field onto Side, and the measure onto Value.
Tableau Server or Cloud:
A site admin must allow the extension by adding its URL to the site's safe list, and the view needs the Download Summary Data permission. Extension URL: https://vizextension.dataskera.com/tornadochart/tornadochart.html

Signing in & access

Tornado Chart is free. Whether you need to sign in depends only on what you are doing. Viewing a dashboard never asks for an account, and authoring is free too.

Viewing a dashboard
No account

People who only view a dashboard are never asked to sign in and are never blocked.

Editing on Tableau Desktop
Optional

Sign in, or continue without an account in a single click.

Editing on Server or Cloud
Free account

Sign in with your Dataskera account to author on the web.

No account yet? Create one free in under a minute. No credit card required.

Format panel

Open the Format panel from the extension menu to customize the chart. It is for the dashboard author and is not shown to viewers. It has four tabs:

  • The Two Sides: which value goes left, one shared axis or an axis per side, and the sort.
  • Bars: bar thickness, row gap, the gap at the centre, and the value axis.
  • Labels: category names down the centre or on the left, the value at the end of each bar as a number or a share, and the gap between the two sides.
  • Color: a palette, a precise colour per category, and the overall opacity.
  • Legend: show or hide it, its position around the chart, an optional show/hide toggle for viewers, the colour swatch, and the content of each entry.
  • Tooltip: show or hide it, its colours, decimals, and a template you write yourself from the placeholders the chart provides.
One axis is the honest default:
The widest bar on either side sets the scale for both, so a small quantity cannot be drawn as large as a big one. Independent axes fill the page better; choose them and the chart says the two halves can no longer be compared by length, and prints where each side tops out.
Two sides, and only two:
A side field holding one value cannot oppose anything and the chart says so. Holding more than two, the first two are drawn and the ones left out are named.
A bar reaching from a centre has no sign:
Negative rows are excluded and counted, because a bar growing away from a centre cannot show one.
One click, the whole pair:
Clicking either bar selects the category on the worksheet, both sides together, because the pair is one row of the question being asked and filtering to half of it would answer a different one.