Do gun ownership predict homicides taking race into account?
You may have seen a plot like this one: The reader is left to interpret that guns cause homicides. It's correct if we include suicides but it's not true for…
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.…
Consequences of racial composition changes in USA 1970-2023
Some years ago, I gave a good idea of a study to a friend, and he did it. But then he just never published his study anywhere, it's just sitting…
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:…
Words can’t bring me down
At least, that's a philosophy of life that some people subscribe to. Others think that words are sort of magic and can hurt you. Even if they are general statements…
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…
Penalization for small n problems: case study of Steam games
For many kinds of ranking websites, users are naturally going to be interested in the leaderboard or top list, the best of the best. This is the same thing for…
Steam game ratings don’t show recency effect
Due to a data error, some of these findings are not entirely true. See next post. Previously, I showed that IMDB movie ratings are inflated for recent movies. I speculated this…
Newest results on the sex difference in intelligence
Richard Lynn noted a 'paradox' or incongruency many years ago (1994): A paradox concerning sex differences in intelligence and brain size has recently been noted by Ankney (1992) and Rushton…