It might be unfair to the word “imperialism”, but I feel I’d leave it with a heavily negative connotation of “undeserved and unwanted/not-agreed-to domination” — so post-WWII military occupation of Germany and Japan was not “imperialism” because their subsequent occupation was arguably deserved, and voluntary religious tithing enriching a religious locus (e.g. Rome 1100-1300, or a local monastery) doesn’t count because it’s voluntary.
This, unfortunately, makes it hard to measure. It also begs the question of perspectives (e.g. Are all military bases “imperial”? What if Japan wants a US base on Okinawa but Okinawa itself does not? ; AND ; Is all foreign investment “imperial”? Then is that an argument against allowing any foreign investment?).
Still, measuring and comparing is easiest with quantization anyway, so I might settle for “imperialism” as simply “domination”, strictly as “elevation of party A interests over party B interests, even when party B might be agreeing” — and then leaving the “is imperialism good or bad?” question murky instead of predefined. That would enable/permit a measurement of:
- military bases (number, size, lease duration)
- military operations (size, target/purpose)
- foreign investment/ownership (direct vs. indirect, size, and duration/volatility (i.e. does it flee in downturns))
- foreign employment (e.g. if a Japanese company’s American office workers get paid better than the home office then that is less imperial; if an American company sends a well-paid American to oversee many low-paid local staff in Vietnam then that is more imperial)
- import-export ratios (a key feature in historic imperialism has been low value extractive industry vs. high value manufactured industry and I think that is likely still a significant feature; total quantity is also very important)
- travel/visa differential (i.e. does one country get easy access to another whereas the reverse is not true?)
- language (when a foreigner and a local meet, which language do they communicate in?)
- if a foreigner breaks a local law, is the foreigner tried locally, or merely sent home?