Small multiples

Synonyms:
trellis chart, panel chart, grid chart, lattice chart
several pie charts

Small multiples are an array of graphs on the same scale that are grouped together in a row or grid and are often used to simplify a data display.

For example, when one needs to show 3 variables, a common mistake would be to create a 3D graph, which is often difficult to interpret. A better method would be to create a separate graph for each category of Variable A, which is composed of a data display for Variables B and C. The graphs themselves can take any form, such as bar graphs, line graphs, or even pie charts.

The key is really that the tiny graphs are all on the same scale, meaning their y-axis all have the same maximum and minimum values. Doing so allows a viewer to compare the mini graphs to one another.

Examples

Gender comparison by location of program

several pie charts

In this example, gender is graphed by location of program.

Source: Stephanie Evergreen

Advice for choosing this method

Choose small multiples when a single graph is too cluttered or complicated because too many variables need to be displayed. Don’t use this method if the scales would have to be altered.

Advice for using this method

Because the graphs are tiny, they need to be very simplified. Eliminate gridlines, tick marks, and any other clutter that isn’t necessary. In terms of labelling, you can usually get away with labelling the leftmost graph in the series and then skip labelling the rest. If possible, order the array of tiny graphs from greatest to least on one category.

Resources

  • How to make a small multiples bar chart in excel

    This blog post from Ann K Emery provides step-by-step guidance for creating a small multiples bar chart using Excel.

    The 10 step process provides detailed guidance and screen shots of each stage of the method.

     

Other ways to compare sets of values

  • Bar chart

    A bar chart plots the number of times a particular value or category occurs in a data set, with the length of the bar representing the number of observations with that score or in that category.

  • Block histogram

    A histogram is a graphical way of presenting a frequency distribution of quantitative data organised into a number equally spaced intervals or bins (e.g. 1-10, 11-20…).

  • Bubble chart

    Commonly used on maps, and x/y-axis plots, or no plot at all, bubble charts communicate the raw count, frequency, or proportion of some variable where the size of the bubble reflects the quantity.

  • Bullet graph

    Bullet graphs encode a single variable as a bar.

  • Deviation bar graph

    Deviation bar graphs are simply two bar charts aligned, where one of the charts runs right to left rather than left to right.

  • Dot plot

    Dot plots encode single data points with circles, often on a line.

Tufte, E. (1983). The visual display of quantitative information. Cheshire, CN: Graphics Press.

Cleveland, W. (1993). Visualizing data. Summit, NJ: Hobart Press.

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