by Anthony Watts, September 18, 2018 in WUWT
Godfrey Dack writes in with this:
Everyone will be familiar with the difficulty of listening to a conversation held with a friend in a crowded room with many other conversations going on at the same time. So it is with many fields of scientific investigation where it is difficult to tease a particular trend out from masses of data. In the first case, we could call the friend’s conversation ‘The Signal’, and the background conversations ‘The Noise’.
In looking at climate data, trends (the signal) can be graphically represented by a (generally) smooth curve, usually flanked by a range of experimentally predicted or actually measured values (the noise). Joining up every point on a graph of such data would give a jagged line which could be thought of as a combination of many alternating functions over a wide range of frequencies.