Comparisons of magnitude (size)

To show:

  • X is bigger than Y
  • A is almost twice the size of B

Comparisons of size are shown most effectively as horizontal or vertical bars. Always begin the y-axis at zero.

Small differences in magnitude, starting the y-axis at a non-zero value

If there are small differences between values sometimes it is necessary to start the y-axis at a non-zero value.

Always put a break in the y-axis if you do not start at zero.

Use a dot (or other symbol) plot to make comparisons between values. The size of the visual element representing the data (dot position) is representative of the data value itself.

You can also show small differences between data by adjusting the deviation. This is changing what data can be seen from a chosen value (the deviation section has more information).