[quote=pri_dk]
The confusion here is that I am talking about the measured value of output (GDP) while you and Dave are talking about the first & second derivatives (growth rate.) The “zero” in zero-sum refers to output. You can call that semantics, but it’s a pretty important distinction.
[/quote]
Ah, yes, that’s the confusion. But… YOU decided that “zero-sum” refers to output, not me (or anyone else so far as I can tell). I thought it was completely and intuitively obvious that my n-sum refers to growth, thus I saw no need to clarify further. Now I know…
