Wait, so you didn't just p hack until you got something to support a narrative you like? Doesn't seem like you know how science works

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May 2, 2023·edited May 2, 2023

As others have noted, PISA is probably not great at scooping up the poorest and weakest students in 3rd world countries. Coverage ratios are also generally lower and there are many scandals of outright cheating.

Sometimes they get caught:


But I suspect in many cases they don't.


An additional factor might simply be that inequality is partly "irrational" in the sense that we've seen a significant rise in economic inequality over the past few decades in the West which are not explainable by cognitive factors. The average American CEO used to have an income of 30X more than the company's average worker in the 1950s and now it is closer to 300X. I doubt American CEOs have gotten smarter by an order of a magnitude over these decades.

So perhaps the left does have a point in that inequality isn't always rational (i.e. can be explained by greater talent and intelligence in all instances)?

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maybe higher IQ variability -> greater riches -> more equality because richer countries tend to have 1. higher social spend. 2. more efficient systems to help the dumb find employment etc.

the effect of cash, rather than preferences of the elite

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I think it's pretty obvious that high IQ countries have less, not more, income inequality. This is due to high IQ countries having better institutions, fewer extractivist elites, and more redistribution. The Nordics are a quintessential example of this, because they are these high-IQ and high-trust countries whose traits are used to produce a high income that is then redistributed.

Of course, you were looking at cognitive inequality, which is different, because one would expect a positive relationship between cognitive inequality and income inequality. I think there are at least two plausible explanations why this is not seen. One is that PISA is much better at capturing the worst students in developed countries than the worst students in underdeveloped countries, and this has always been the case. This may be a conscious effort by underdeveloped country governments, but it could also just be a consequence of the fact that there is more attrition in underdeveloped countries schools, so more of the worst students drop out before they can take PISA.

The second explanation is that if greater cognitive inequality is a sign of a high average IQ country, then the average IQ might end up weighing more than cognitive inequality, for the reasons I cited above about high IQ countries having better institutions and more redistribution.

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If the European data are a guide, it seems that the Gini coefficients used in the study are calculated for something that in European sources (EU-SILC) is called "equivalised disposable income". This includes all monetary income going into a household whatever the household member generating this income: market income (salaries, wages, self-employed gains, etc.) but also public transfers (public pensions, unemployment benefits, family benefits, sickness benefits, basic income benefits and the like). From this some taxes are substracted (income tax, an employee's social security contributions). This "disposable income" is then divided by the numer of equivalent adults in the home (using a so-called modified OECD scale) and assigned to everyone of the members of the household.

It is known that those public transfers substantially reduce market income inequalities, and that their influence on "final income inequality" can vary greatly across countries.

So, maybe market income inequality may be associated to cognitive inequality, but it is not obvious that a measure of income inequality that includes taxes and public transfers should be.

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it should be expect that IQ-Income correlation is higher in low IQ countries. Because they have not enough skilled workers. So demand is higher. Additionally maybe there is threshold effect in some sectors.

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Fascinating and kudos for publishing a negative result. It looks like you retrieved the GINI coefficients from the world bank in 2021, was that the 2020 observation? Could be pretty different from pre-COVID due to the pandemic. Also, I believe Gini coefficients are not always comparable across countries (sometimes using consumption rather than income, age distributions since old people have low incomes, and post-tax/transfer)

It would be interesting to see if the results flip if you used, say, the ratio of 90th to 50th percentile of pre-tax/transfer income among 25-54 prime age workers.

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Very interesting! I thought in the past that GDP and average PISA score correlation would be lower than GDP-elite PISA score correlation, but I found out I was wrong.

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If Lynn never collected SD, then how or why did he compare the IQs? One country might have a SD of 15, another 16 or 17, making the percentiles different.

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