Peter Fallesen

Engineers of Jihad A groundbreaking investigation into why so many Islamic radicals are engineers

Gambetta and Herzog wrote a book that indirectly tried to parse out the mechanisms by looking at Islamic extremism press.princeton.edu/books/hardco...

Fears that falling birth rates in US could lead to population collapse are based on faulty assumptions While the changes in population structure that accompany low birth rates are real, the impact of these changes has been dramatically overstated.

Want to know why demographers aren't panicking over low birth rates? @lesja.bsky.social, @shelleydclark.bsky.social, & I have a new piece in @theconversation.com explaining the faulty logic that underlies the low birth rate-induced population panic than fuels the pronatalism movement. 1/n

A Nazi owns Twitter, right wing billionaires own the Wall Street Journal and the LA Times, and CBS is run by a right wing nepo baby who just fired one of the network’s biggest stars for criticizing Donald Trump. Here’s why America has a left-wing media bias problem.

Implications: when studying how events (disasters, policy changes, etc.) affect birth outcomes, we must account for conception rate changes. What looks like changing health might result simply from parts of the population changing conceptive behavior. 4/4

More generally, underlying baseline risk matters for magnitudes. We find that temporal variation in conceptions explains around 8% of preterm birth fluctuations for White mothers, and 12-15% for Black mothers. 3/4

Using US birth data (2010-2019), we show that a conception "shock" creates a wave pattern: fewer conceptions → fewer preterm births beginning from 5 months later → but more from 9 months before rates normalize. 2/4

🔴New working paper with @marcocozzani.bsky.social and @juhoharkonen.bsky.social. We describe the temporal link between conception timing and preterm birth rates. When conception rates fluctuate, preterm birth proportions shift predictably but with different magnitudes depending on baseline risk. 1/4

Are a few people ruining the internet for the rest of us? Why does the online world seem so toxic compared with normal life? Our research shows that a small number of divisive accounts could be responsible – and offers a way out

Much of that distortion can be traced back to a few hyperactive users
-Just 10% of users produce 97% of political tweets
-A mere 0.1% of users share 80% of fake news
This leads us to believe that society is more polarized, angry, & deluded than it really is. www.theguardian.com/books/2025/j...

Congrats Zach!

but no difference across post-dissolution living arrangements, including for joint living and parents' subsequent partner status. With M.N. Nielsen and M. Gähler. [2/2]

Our article on parental union dissolution and children’s emotional and behavioral problems appears in the most recent issue of @sfjournal.bsky.social. We find a longterm increase in SDQ score following parental union dissolution [1/2]

academic.oup.com/sf/article/1...

Decline and Prosper! This book considers the historical context as well as the full breadth of factors that drive fertility rates across the globe.

My book, "Decline and Prosper!", presents a comprehensive and evidence-based overview of the causes and consequences of global fertility decline.
I argue that low fertility is inevitable, yet also has positive effects. We should help people have the children they want bit.ly/35Hm3Yk

Economists looking at an idea from sociology literature that they will be the first to write a paper on.

Despite living in wealthy societies, too many children still grow up in poverty.

What can be done—nationally and locally—to change this?

Read our latest Policy Brief for the #Mapineq project by @janierola.net & @mjantti.bsky.social and find it out!

🔗 tinyurl.com/54bwznh9

Reckless disregard for the truth coming from cops, doctors, and scientists: A rant.
statmodeling.stat.columbia.edu/2025/06/24/r...

As some of you guessed, the two models are statistically indistinguishable. The answer is Model 1, but there was no way to tell from the data. I was very surprised when I first saw this. Here we show that this confounding of heterogeneity and reinforcement is general: www.pnas.org/doi/10.1073/...

Declining Fertility Leading to Long-Term Stability in Demographic Dependency Ratios Higher dependency ratios associated with the demographic transition can be considered a manageable challenge for many.

“We argue that higher dependency ratios associated with the demographic transition can be considered a manageable challenge for many”

In Nordic welfare states, not all family policies promote equality. A new AJS article by Evertsson, Moberg & van der Vleuten compares earnings penalties in same- and different-sex couples across countries, showing how policy design shapes work–care divisions www.journals.uchicago.edu/doi/10.1086/...

Union dissolution and children’s educational achievement: separating effects of school and non-school environments* Abstract. We study whether the educational disadvantage of children from households where parents have dissolved their union is due to selection or deterio

Children from dissolved families benefit 5-7% less from non-school learning environments, with effects increasing over time. Schools showed little ability to compensate, suggesting deteriorating home environments post-separation primarily drive achievement gaps. New article out in ESR

Forsker efter 4 stop på berygtet gade: Her er »den oversete historie« om kriminalitet  Er danskerne virkelig blevet langt mindre kriminelle, end de var i 1980’erne?

Forsker efter 4 stop på berygtet gade: Her er »den oversete historie« om kriminalitet  #dkvid #dkforsk

What is life expectancy? And, even more important, what it isn’t Dr. Ilya Kashnitsky is a demographer @ Statistics Denmark.

Tnx. Turned it into a blog post since
ikashnitsky.phd/2021/life-ex...

@ikashnitsky.phd had a fantastic breakdown of why it is called what it is called and what it actually measures awhile ago over on Twitter, before it turned into a barren hellscape

@rockwoolfonden.dk and Duke have jointly developed a public use dataset of population rates of child protective services contacts in the global North. Read more about it in this N- @iussp.bsky.social piece

The mainstream media has enabled Trump’s war on universities | Jason Stanley For the past decade, the US press has fueled a moral panic over leftists on campus while failing to report on the right’s assault

Essential reading for anyone who cares about higher education and the media’s role in its dismantling.

www.theguardian.com/commentisfre...

Ja, for fødselsraten beskriver netop kvinders fertilitetsadfærd, men barnets status bygger på begge forældre

Nordic Demographic Symposium is back in Denmark 🇩🇰 @demografi.dk

@pfallesen.bsky.social is showing some brilliant #dataviz in his overview of fertility dynamics 🤩

Multi-field postdoc opening at Royal Holloway. Great PIs, good colleagues

My Canadian university, Queen's, is offering TWENTY 4-year funded PhDs (40k CAD/yr) for a student of ANY citizenship who has been accepted at a top 100 US university but have had offer rescinded OR are reconsidering offer due to US policy.
Details found here👇

www.queensu.ca/grad-postdoc...

Excited to release this working paper