
Average Power: A Cautionary Note [pdf] - luu
https://statmodeling.stat.columbia.edu/wp-content/uploads/2020/08/avgpower.pdf
======
nickt
Wasn't the type of power I expected:

Abstract

Replication is an important contemporary issue in psychological research, and
there is great interest in ways of assessing replicability, in particular,
retrospectively via prior studies. The average power of a set of prior studies
is a quantity that has attracted considerable attention for this purpose, and
techniques to estimate this quantity via a meta-analytic approach have
recently been proposed.

~~~
Animats
_Wasn 't the type of power I expected._

Me either. I thought it was going to be about power measurements for non-
standard waveforms. Switching power supplies, inverters, and other devices
generate loads and outputs that don't look like a nice sinusoidal AC waveform.
There are power factor problems, where voltage and current are not in sync.

It's hard to measure average power for strange waveforms. Average voltage
times average current can be way off from average power. You need the integral
of the product of voltage and current. The simplest way to get that is
measuring the heat emitted from a resistor in series with the load, and that's
what a classic RF wattmeter does.

It's a practical headache for transformers, power distribution, and such.
Transformers lose efficiency and heat up on such waveforms. Motors don't run
well This used to be a big problem with low-end inverters for solar systems.

The "free energy" people run into this trap. They build some weird oscillator,
measure voltage and current, and think they got out more than they put in.

So that's "Average power, a cautionary note" for electronics.

~~~
dTal
It's quite common to see "I thought article was going to be about <x>" on HN.
Less common for the disappointed punter to dive right in and write the article
they expected. Nice one!

