Hmm, I would actually love (genuinely) to hear more. My impression is that standardized testing of Intelligence Quotient explains way way less than popular imagination & movies think.
Studies like these [1] [2] get a lot of newspaper time, but they're largely rebuked on methodological or overreach grouns, and honestly, there's sweeping generalizations and then there's saying "Anything from California is automatically bad due to low average IQ".
As well, the spread across ALL states is barely 10% [3]
edit: Though, by that logic, USA should start mimicking everything we canucks do! I look forward to you adopting our universal health care and bilingualism and Her Majesty The Queen! :-D [4]
I don't know about correlation between average IQ and a country/state performance (e.g. GPD performance capita) but there is plenty of research that show correlation between a person's IQ and expected income/wealth.
It's also intuitive. The whole path to college, at least for hard sciences, partially select for IQ. And college education correlates with higher income.
