Crémieux Profile picture
Jan 8, 2024 • 10 tweets • 3 min read • Read on X
Achievement gaps do not simply reflect geographic sorting.

This fact has been known for more than a century now, but some people still don't get it.

Shortđź§µ

First: achievement gaps exist within the same schools.Image
This is not just true for race, it is also true for class. Image
When it comes to district-level family incomes by group, we see that intercepts differ.

In other words, even when lower-performing groups are wealthier, they tend to do worse than higher-performing groups. Image
If you're reading this, you probably know that this replicates the results for rearing household income (1/3):
Consider Reardon, Kalogrides & Shores (2019). They found that even in districts where lower-performing groups had higher SES than Whites, they still tended to perform worse.

In this picture, 79% of the mean Black-White gap is independent of SES. At the metro level, 62% was. Image
It is a pernicious myth that test scores and achievement gaps are mere reflections of geography and that geography plays a major causal role in test scores.

The truth is that their association primarily reflects selection.
I neglected to mention this: results from Moving to Opportunity suggest no significant effects on test scores.

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More from @cremieuxrecueil

Apr 17
One of the really interesting studies on the psychiatric effects of maltreatment is Danese and Widom's from Nat. Hum. Behavior a few years ago.

They found that only subjective (S), rather than objective (O) maltreatment predicted actually having a mental disorder.Image
Phrased differently, if people subjectively believed they were abused, that predicted poor mental health, but objectively recorded maltreatment only predicted it if there was also a subjective report.

Some people might 'simply' be more resilient than others.
I think this finding makes sense.

Consider the level of agreement between prospective (P-R) and retrospective (R-P) reports of childhood maltreatment.

A slim majority of people recorded being mistreated later report that they were mistreated when asked to recall. Image
Read 6 tweets
Apr 15
Nature finally published it!

The Reich Lab article on genetic selection in Europe over the last 10,000 years is finally online, and it includes such interesting results as:

- Intelligence has increased
- People got lighter
- Mental disorders became less common

And more!Image
They've added some interesting simulation results that show that these changes are unlikely to have happened without directional selection, under a variety of different model assumptions. Image
They also showed that, despite pigmentation being oligogenic, selection on it was polygenic.

"[S]election for pigmentation had an equal impact on all variants in proportion to effect size." Image
Read 9 tweets
Apr 10
I still think this is one of the most important recent papers on AI in the job marketđź§µ

The website Freelancer added an option to generate cover letters with AI, and suddenly the quality associated with cover letters stopped predicting the odds of people getting hired!Image
LLMs do a few things to cover letters.

Firstly, they increase the quality, as measured by how well tailored they are to a given job listing. Image
Second, they make job applications in expensive, so people start spending less time shooting off applications.

More, rapidly-produced job applications becomes the norm. Image
Read 8 tweets
Apr 6
The authors of this work now have a newer study with a nine-times larger sample!đź§µ

The overall result is that the rich are:

- More risk-tolerant, open to experiences, extraverted, and conscientious
- Less neurotic
- No more agreeable than normal, non-rich people Image
Now, we have a breakdown of different types of rich people!

Among those who could be classified, the majority of the rich (79%; >=€1m net worth) were self-made, with a smaller, 21% share whose wealth came primarily from inheritances. Image
How do inheritors and the self-made differ in personality?

They're both more risk-tolerant and less neurotic than the average, but the inheritor profile looks like a mixture between the overall rich and normal people, with more agreeableness, less openness, etc. Image
Read 8 tweets
Apr 3
My latest article asks and answers the question:

When did being fat become a thing for poor people?đź§µ

We should start with the observation that, as countries get richer, they tend to get fatter. Image
This might seem contradictory to the whole thesis, but it's not.

Countries become obese with wealth because poorer people within them are able to get fatter as they become richer.

The ecological and individual relationships differ.

Look internationally: Image
Now, we have good data for much of the U.S., and it tends to agree with Swiss and Dutch data, in that the inversion of the relationship between obesity and social status was a post-WWII, mid-century thing.

It precedes the welfare state, and then it's fairly constant. Image
Read 8 tweets
Mar 23
Why have testosterone levels been rising over time?

The testosterone levels of American men are up compared to what they used to be, but no one has a good explanation.

Let's look through some possibilitiesđź§µ Image
Is it perhaps because of a racial composition change?

No.

Different races tend to have similar testosterone levels and trends within groups are similar. Image
Is it perhaps because of age composition change?

No.

The decline by age is much more graceful than people tend to suspect, and within each age group, levels are up without survey weighting, and in nearly all with it, they're still up. Image
Read 34 tweets

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