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:
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.