What is noise?

Abstract

The concept of “noise” plays a crucial role in the statistical analysis of data. As an example of a noisy record consider Figure 1 that shows the ground motion of the seismological station NE51 in St. Petersburg after an earthquake in Egypt. (In earthquake seismology, periods may be orders of magnitude larger than in exploration seismology, but the principles are the same.) This time series shows no distinct arrivals or other apparent signatures of an organized nature. Given the proximity of the recording station to a major population center and to the coast, such a noisy record does not seem to be very surprising.