RE: What if every student in America is measured but other countries only measure from their very best schools?
There are people who claim that China’s city of Shanghai is actually doing this.
Yes, this is 100% true. NO ONE shows up in China and says "I want to do a large and comprehensive survey of your education system and students, OK?" Any such surveys are conducted 100% on Chinese Government terms, with outcomes they plan in advance.
Once the CCP, after a lot of political consideration and internal debate, decides to participate in such an international survey, they will select who participates. They will certainly choose the best areas and best schools of a city like Shanghai or Beijing. Nothing is left to chance.
And groups like the UN or Intl NGOs go along with it, because 1) they are stupid, 2) have political groupthink, and 3) their job is to go along with any expected results.