Signal and noise

The useful information in a graphical or tabular display of data is called its signal. Parts of the display that do not contain information that can be usefully interpreted are called noise. We can distinguish:

Non-data noise
This 'non-data ink' includes unnecessary graphics and gridlines that have been added to displays.
Data noise
This is information from the data that is displayed but does not help the reader to understand the 'signal'.

Noise make it harder to detect the signal in a display and should be avoided.

Significant digits

Many tables contain values that are reported with more significant digits than necessary. Usually the pattern of values in a table can be understood from only their first 2 or 3 digits — the remaining digits are data noise.

Reducing the number of significant digits and rearranging the columns makes the information easier to understand.