Let's say, for the sake of argument, that people in the '60s were twice as smart as people now.
The average IQ of the people then would be 100, and the average IQ of people now would also be 100, even though there was a huge difference in intelligence. This is because 100 is defined as being the average rather than being an absolute measure.
Ah. okay yeah that makes sense. I didn't realize it's a relative measurement. I'm surprised it's not more robust. Something like using historical results to compare against, and updating tests in a very standardized way where the math/logic is always fairly similar, but the fact checking/knowledge that requires understanding of current world might be different data wise, but tests similar attributes or qualities.
The average IQ of the people then would be 100, and the average IQ of people now would also be 100, even though there was a huge difference in intelligence. This is because 100 is defined as being the average rather than being an absolute measure.