alt Hacker NewsPurchasing power for what? Consumer goods? Most purchasing power calculations are completely bogus because they rarely compare goods of equal quality.
A neighborhood with just a Walmart doesn't have higher purchasing power than a neighborhood with just a Whole Foods.
Commodities. Raw materials with which all goods and services are made. Coffee, sugar, wheat, pound of beef, gasoline. Also products which are supposed to be identical like a Big Mac. Purchasing power is hard to measure but it’s a question studied deeply by economists.