Matrix Chart

Synonyms:

Heat map, Marimekko chart, Mosaic chart

A matrix chart shows relationships between two or more variables in a data set in grid format. Essentially, the matrix chart is a table made up of rows and columns that present data visually and can be seen as the visual equivalent of a crosstabulation that divides data between the variables. The matrix chart is formed through at least two variables, for the X- and Y-categories. If there is a third or fourth variable, colour or other another dimension can be added to the matrix to represent it.

Examples

In this example, we compare players (Y-axis) against six variables on the X-axis. The font is intentionally small because in this example colour was applied to see where individual players stood out. Looking at the rows, the variables in which that player stands out are darker compared to other, weaker stats.

Looking at the columns, players that stand out for a particular variable are easily spotted by the darker color. This matrix chart is accomplished through Conditional Formatting in MS Excel.

Source: Dave Shellard and Mark Vogelgesan

In this example, the matrix chart is essentially an enhanced column or bar chart where data is presented in proportion to the other values. This example requires some MS Excel work to format the data set correctly (see reference or guide below).

American Society for Quality

In this Matrix chart, simple dots represent the high and low values. The major producers and buyers of a model are identified in the columns. Reading the rows, the trends in model development and purchasing are identified.

Source: http://asq.org/learn-about-quality/new-management-planning-tools/overvie...

Many Eyes: Matrix Chart Guide

More advanced software tools may allow for another dimension, such as this example from Many Eyes. This tool allows for two additional data elements to be shown in pie chart format with in the matrix chart.

Source: www-958.ibm.com/software/analytics/manyeyes/page/Matrix_Chart.html

Advice

Advice for CHOOSING this option (tips and traps)

Matrices are useful for visually displaying your crosstabs that can be otherwise overwhelming to read. If you want to publish your crosstab result, consider adding an element of colour or symbol to drive the reader’s attention. With additional software you can make the matrix chart more advanced and show additional variables in a comparative manner.

Advice for USING this option (tips and traps)

Because so much data is presented in a matrix chart, keep the visual display of the graphs themselves very simple and uncluttered.

If actual data elements are printed, reduce the font size so the colour carries the message.

Resources

Guides

Matrix Chart. Mouse Trax Computing Solutions: different visual examples and step-by-step instructions for creating different kinds of matrix charts from John Peltier (2012)

Excel Panel Charts: instructions on creating various types of matrix charts using Excel

Example

Matrix Chart Guide: Example of the circular matrix chart from Many Eyes (2011)

Other ways to see relationships among data points

Scatterplot
Displaying the relationship between two quantitative variables plotted along two axes. A series of dots represent the position of observations from the data set.

Network Diagram
Displays how people (or other elements) in a network are connected.