Crémieux Profile picture
Sep 5, 2024 13 tweets 5 min read Read on X
How bad are Richard Lynn's 2002 national IQ estimates?

They correlate at r = 0.93 with our current best estimates.

It turns out that they're really not bad, and they don't provide evidence of systematic bias on his part🧵 Image
In this data, Lynn overestimated national IQs relative to the current best estimates by an average of 0.97 points.

The biggest overestimation took place in Latin America, where IQs were overestimated by an average of 4.2 points. Sub-Saharan Africa was underestimated by 1.89 pts. Image
Bias?

If you look at the plot again, you'll see that I used Lynn's infamously geographically imputed estimates.

That's true! I wanted completeness. What do the non-imputed estimates look like? Similar, but Africa does worse. Lynn's imputation helped Sub-Saharan Africa! Image
If Lynn was biased, then his bias had minimal effect, and his much-disdained imputation resulted in underperforming Sub-Saharan Africa doing a bit better. Asia also got a boost from imputation.

The evidence that Lynn was systematically biased in favor of Europeans? Not here.
Fast forward to 2012 and Lynn had new estimates that are vastly more consistent with modern ones. In fact, they correlate at 0.96 with 2024's best estimates. Image
With geographic imputation, the 2012 data minimally underestimates Sub-Saharan Africa and once again, whatever bias there is, is larger with respect to Latin America, overestimating it.

But across all regions, there's just very little average misestimation. Image
Undo the imputation and, once again... we see that Lynn's preferred methods improved the standing of Sub-Saharan Africans.

There's really just nothing here. Aggregately, Lynn overestimated national IQs by 0.41 points without imputation and 0.51 with. Not much to worry about. Image
The plain fact is that whatever bias Lynn might have had didn't impact his results much. Rank orders and exact estimates are highly stable across sources and time.

Want to learn more? See:
See this too, and note that it depicts rank correlations:
See this as well, on how very diverse data produces the same results:
And finally, see for the source of our current best estimates.sebjenseb.net/p/most-accurat…
It also might need to be noted: these numbers can theoretically change over time, even if they don't tend to, so this potential evidence for meager bias on Lynn's part in sample selection and against in methods might be due to changes over time in population IQs or data quality.

It might be worth looking into that more, but the possibility of bias is incredibly meager and limited either way, so putting in that effort couldn't reveal much of anything regardless of the direction of any possible revealed bias in the estimates (not to imply bias in estimates means personal biases were responsible, to be clear).
Some people messaged me to say they had issues with interpreting the charts because of problems distinguishing shaded-over colors.

If that sounds like you, don't worry, because here are versions with different layering:
Image
Image

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More from @cremieuxrecueil

Apr 3
Timeline's feeling down. Thread of good news.

At every age, the incidence of dementia is down. As a society, people are no longer suffering dementia nearly as often! Image
The world over, child mortality is way down. It's unusual for parents to experience the death of a child these days, where even a century ago, it was the global norm. Image
Each year, novel gene therapies are approved.

The number of gene therapies in the pipeline is also rapidly increasing. There is tons of progress to be made here, and the main issue is regulatory.

We have lots of low-hanging fruit in curing disease! Image
Read 13 tweets
Apr 3
Which is more impressive for China, its

GDP Per Capita, or its

Actual Individual Consumption Per Capita (AIC is a superior measure of how rich its people actually are. It's based on how much they really consume)

Answer is below.
Here's the GDP Per Capita data. Image
And here's the AIC data. Image
Read 5 tweets
Apr 3
There's a common type of misunderstanding that sounds like this:

"If taller people tend to be more educated, and women tend to be shorter than men, how do you explain women tending to be more educated?"

The issue has to do with intercepts. Consider this plot: Image
You can see that, among Whites, women tend to be shorter than men, and they tend to have lower earnings.

But at the same time, to similar degrees in both sexes, taller people tend to have higher earnings.

Perplexed? You shouldn't be.
The fact is that there's more to this that differentiates men and women than height, so the intercept for women is shifted down, even though the slopes of the height * income relationship are fairly comparable.

You could also ask the same thing about race.
Read 8 tweets
Apr 2
Debate about the value of essays in college admissions missed a key point:

Essays are biased, so should not be used.

Here's an example: High-income people know 'what to write' to look good to raters, so they outperform on essays relative to their other qualifications. Image
This shows up by race, too, and that's why admissions departments use essays to infer race for the express purpose of discriminating.

Write that you're Black; that you grew up as a poor immigrant; that you're gay or a cripple.

They love that!

The reason essays do not have a role to play in the admissions process is because they're biased. It's plain, it's simple, it doesn't need to be discussed any further.

And here's some good policy: Use tools that are not biased or lose public funding.
Read 4 tweets
Apr 2
A new meta-analysis and systematic review on the effects of social media abstinence interventions on mental health has been published.

First result: No effect on positive affect: Image
Second result: No effect on negative affect. Image
Third result: No effect on life satisfaction in general. Image
Read 6 tweets
Apr 2
Happy Autism Awareness Day! I think too many people are 'aware' of autism.

Have you ever met someone who claims to be autistic, but they've never been diagnosed?

Self-reported autism spectrum disorder (ASD) is practically uncorrelated with real, clinician-diagnosed autism🧵 Image
Sort self-reporters into those with high and low ASD scores, and you get the bars on the left. The "high-trait" self-reporters look like people with diagnosed autism (ASD column).

But they're more socially anxious (middle) and avoidant (right). Image
So far, the means of distinguishing diagnosed from self-reported autistics have been crude.

To get a more nuanced understanding of their differences, we have to look at behavior.

For that, we'll start with the social control task.
Read 14 tweets

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