Is there a formal difference between weighted average and weighted mean?
I get corrected to the latter if I type in the former in wikipedia, and then there is a lot of stuff about the name "average" so I'm not sure about anything anymore.
As a small bonus question: Logically, what is the field which introduces weighted averages? To associate it with measure theory seems a little over the top.
As far as I know average and mean informally are interchangeable terms.
As far as weighing, the classical Greeks already were aware of not only arithmetic, geometric and harmonic means but possibly as many as 10 different types.
As discussed in Graziani and Veronese in "How to compute a mean? The Chisini approach and its applications" Am Stat 2009:
The authors also write:
Examples of invariance requirements and resulting means listed in Table 1 include weighed arithmetic, weighed quadratic, weighed harmonic, weighed geometric, weighed power, weighed exponential.
The paper works through several easily followed practical applications including Mean Traveling Speed, Mean Interest Rate, Mean Exchange Rate and others.
Finally, the authors note that Chisini Mean does not directly address important statistics like mode and median, but generalization by A. Herzel in 1961 (A paper I've been searching for) recasts the invariance constraint as an optimization problem to handle these.