alt Hacker NewsYeah. The linked source is upfront about that, but its the closest thing we have to a real study sadly. As I said, the averages are close anyhow.
Scholars have from time to time thrown their careers away by trying to get better numbers, inevitably some group doesn't like the outcome and they become embroiled in endless debate while their career implodes. For example, the major sources cited in The Bell Curve have had their titles stripped and been hounded to the ends of the earth.
All these years later people are still specifically authoring papers to debunk their work.
https://www.sciencedirect.com/science/article/abs/pii/S01602...
We will never see real numbers. This, or other things like it, are literally the best it will ever get unless someone sacrifices their career, and maybe their own safety, to gather better data.
There's a persistent myth that it's impossible to do science in this field and that people who try are cancelled. That's obviously false. You can just look this up. It's a fertile field and people are coming at it from multiple angles --- just watch arguments between behavioral and molecular geneticists on Twitter some time.
The people who actually are (/were) hounded are people like Richard Lynn, the godfather of "average IQ by country" data sets. That's because their data sets are fraudulent; not in a subtle way, but very directly: for instance, data for Sub-Saharan African countries are taken in many cases exclusively from mental health facilities, the only places IQ tests are done in any significant numbers in those places.