Sorry if this is noob-ish, but I was doing some really basic analysis between two data-sets and saw this was used as a way to calculate a sort of "normalized difference" (deviation?) between the old and new values. Again, my apologies for not using the mathematically correct terminology.
In Excel (because that's where I found it), using cells
B1 for example, it's
ABS(A1-B1)/MAX(A1,B1). In WolframAlpha it's
Abs[x - y]/Max[x, y]. Formally:
Is there a name/precedent for this, maybe in the realm of statistics or analytics, or is it just something the guy before me made up?