Dataskera

Correlation Matrix

Which of these measures move together, worked out here from the rows on the sheet rather than read from a column somebody computed earlier. That is the whole difference between this and a heatmap: a heatmap shows a number that already existed, and this one computes the coefficient in your browser, names the method it used, and reports how many rows stood behind every cell.

Data Requirements

Your Tableau worksheet should include:

  • 2 to 10 Measures for the Measures encoding. Every pair of them is measured against every other.
  • 1 Dimension for the Level of Detail encoding. The dimension that defines one observation, so each row of the sheet is one data point.

Add Correlation Matrix to your worksheet

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

Download correlationmatrix.trex

Direct link: https://dataskera.com/downloads/correlationmatrix.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 correlationmatrix.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 two or more measures onto Measures, then drag the dimension that defines an observation onto Level of Detail.
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/correlationmatrix/correlationmatrix.html

Signing in & access

Correlation Matrix 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:

  • How It Is Measured: Pearson or Spearman, one half of the grid or the full square, and the order of the measures.
  • The Scale: the colours for move together, move apart and unrelated.
  • Cells: the coefficient in each cell, the diagonal, hiding the weak relationships, and the gap between cells.
  • 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.
The grain is yours to set:
Without a dimension on Level of Detail, Tableau delivers a single aggregated row per measure, and a coefficient over one row means nothing. The chart says exactly that rather than drawing a grid of n/a.
Pearson or Spearman is a real choice:
Pearson compares the values themselves, finds straight-line relationships and can be carried by a single extreme row. Spearman compares ranks, so no one outlier decides the answer and a relationship that is steady but not straight still shows.
Pairs are measured pairwise:
A row missing one of the two measures is not evidence about that pair, so it is left out of that pair alone rather than knocking out the whole row or being filled with a zero. Every cell reports its own sample size in the tooltip.
A measure that never moves has no correlation:
The denominator is zero and the honest answer is that there is none, not that it is perfect. Those cells read n/a and the chart names the measure that stood still.
This chart has no Color tab:
A coefficient runs on one scale from minus one to one, so its colours are a ramp rather than a palette of members. The three ends of the ramp sit on the General tab instead.