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 25
Why have autism rates risen over time?🧵

I have just put out an article dealing with numerous misconceptions about this topic, and a complete explanation of why autism diagnoses have become more common.

It starts with acknowledging that more kids are diagnosed than in the past: Image
But this is misleading for a few reasons.

One has to do with how this data was sourced. We didn't have a DSM with autism in it before 1980, so all the oldest people in this cohort were diagnosed as adults.

Adults are underdiagnosed. Go out of your way to diagnose? Same rates.Image
So something is off about this graph.

A major issue is that the older diagnoses here were done under a more arbitrary criteria: Autism has only been a described thing since Kanner's studies in 1943 and mass diagnosis kicked off in 1980.

Before 1980, diagnosis was often crazy:Image
Read 16 tweets
Apr 24
In 2016, researchers found that the minority-White wage gap was overestimated by about 10% because, at work, non-Whites tended to partake in more leisure, waiting around, etc.

They delayed releasing the study out of fear Trump would "use it as a propaganda piece." Image
They explicitly admitted that they let their personal politics get in the way of releasing a study with contentious but correct findings.

That doesn't inspire trust, but at the same time, given the topic, it might!
This isn't the worst example of scientists hurting the public for political reasons.

More infamously, this guy stopped the release of the COVID vaccines to prevent Trump from winning re-election in 2020, killing tens of thousands in the process. Image
Read 5 tweets
Apr 23
Aspartame?

What is it? Where is it from? What does it do? Is it harmful? What do health agencies think of it?

And why might the HHS be planning to ban it from American food?

Here's the aspartame review thread🧵 Image
Aspartame is a sugary sweet synthetic molecule that's 200 times sweeter than sucrose.

More than half of the world's supply comes from Ajinomoto of Tokyo, better known for bringing the world MSG. Image
Because aspartame is so sweet, a little bit goes a long way.

The high levels of sweetness contained in very small quantities of aspartame make it ideal for making super low-calorie diet drinks like Diet Coke. Image
Read 34 tweets
Apr 22
When you match different American ethnoracial groups on socioeconomic status, the known differences in intelligence still persist. Image
This shows up in many datasets and persists whether using measures of parental or attained socioeconomic status:
This difference after SES stratification can be understood in dramatic terms.

For example, Asians with parents who merely graduated high school tend to be smarter than Blacks whose parents have graduate degrees.

Read 6 tweets
Apr 20
I don't think Bernie realizes what he's asking for🧵

The Bennett Hypothesis holds that universities alter their prices to capture additional funding that becomes available to students.

When Grad PLUS loans rolled out, the most exposed programs jacked up prices more: Image
If you want to "fix" this situation within reason, you need to cut funding.

Doing that has disproportionately negative impacts for the educations of people from socioeconomically worse off backgrounds. Or in other words, it hurts upward educational mobility for the poor.
Or, you could provide this presidential administration with a gift:

Centralize the universities and have the government more directly control all the funding. Make them "free".

This is far more likely than alternatives like 'Just give universities infinite money', but still bad
Read 4 tweets
Apr 16
Compared to twenty years ago, kids are eating some types of ultraprocessed foods more and some types less🧵

For example, one thing there's proportionally less of is sugar-sweetened beverage consumption. Meanwhile, there's relatively greater sweet snack consumption. Image
Overall, the ultraprocessed food (UPF) consumption share is up across young ages to similar degrees.

The increase is definitely there, but it isn't dramatic. For example, going from 61% to 67.5% is an 11% increase in twenty years. Image
The increase in consumption is not differentiated by the sex of children.

In other words, boys and girls are both eating a bit more ultraprocessed food. Image
Read 14 tweets

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