Which countries are best at esports? 2026 update
Given the ease of obtaining scraped datasets with Claude Code, I thought we could update my 2019 study of mental sports with the newest data and better methods. The primary…
Meta-Analysis of American Race Differences in Intelligence
So our new meta-analysis of the American race gaps in IQ is published! Kirkegaard, E. & Jensen, S. (2025). Meta-Analysis of American Race Differences in Intelligence. Mankind Quarterly, 66(2), 290-300.…
Dysgenics for whom?
Some time ago, we published studies showing that the negative correlation between intelligence and fertility varies by other factors. Specifically, we found that it varies by religiousness and conservatism, in…
Motivated reasoning and intelligence
Years ago, a very flashy finding by Kahan and colleagues (2017) got popular (1200+ citations). It goes like this, you give people some matrices of fake study data like these:…
New test site: taketest.xyz
Using Claude code I am realizing some projects that were always waiting for a sudden burst of manic energy. These projects now only take some hours of chatting and revising…
Does assortative mating work?
In my recent post about differences on the tails, a good comment was posted by Kristine: Is there any correlation between IQ gap and divorce, I wonder... The generation observation…
New York Times is back on the race science beat
Back on the 23rd October 2025, some journalist I hadn't heard of called Mike McIntire emailed me. He said he was writing some smear piece for the New York Times,…
Assortative mating and differences
Cremieux has a viral post showing the absolute IQ gaps for spouses/partners as a function of the smartest spouse: This finding is trivial but apparently surprising to many people judging…
Good science on national IQs
Shae Mclaughlin (SM) has a new blogpost attacking national IQs. I thought it would be suitable to provide the usual rebuttal since I don't see any such post yet. She…
Understanding audit (resumé) studies
John B. Holbein is a mild mannered economist on X. 2 days ago he posted a long post on Lee Jussim's new review paper of racial discrimination in hiring. Jussim…