The Natural Philosopher wrote:

What you are essentially doing when analysing, smoothing, or whatever a
time series, is applying a low pass filter to it: What the filter has as
output is critically dependent on the form of the filter. You are merely
comparing two different forms of filter..and if they give different
results, that merely calls into question the validity of using ANY of them.

I know it's a been as while since I did any statistics in anger, but
from my first lecture in college in 1963 up to what's laughingly
called retirement, I've never heard of statistics being called a LPF.

Perhaps the picture in my mind, of a LPF rejecting HF components of
something, isn't what I see as being done by statistics, which is to
discard nothing in orderto return the best estimates of the provenance
of the data.

How would a comparison of say, satellite data analysed by two
different organisations, with ditto from ground-based data, by putting
them through an analysis of variance, be classed as low-pass
filtering?

Apologies if I appear dim, but I'm struggling to visualise the LPF
concept.