Prof @UniLeipzig @ifkmw & Institute for PolSci @crifc_de @cdp_org (Private account & personal opinions, of course.)

Joined November 2009
Christian Pieter Hoffmann retweeted
It is deeply discouraging that “evidence is the bottom line in any empirical inquiry” needs saying at all.
Recent prescriptions and policies would have us judge research by non-evidentiary standards, e.g. presumed political impact and scholar identity. In a new essay, Tom Clark and I argue empirical claims should instead be evaluated based on evidentiary strength. We outline a framework for judging evidence, and show its usefulness by revisiting high-profile scholarly disagreements spanning policing, political violence, election administration, and terrorism, before critiquing non-evidentiary approaches. We also argue social science needs a culture that is hospitable to critique—rather than one which condemns critics as “bullies”—if quality standards are to be upheld. dropbox.com/scl/fi/fsgpflron…
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Christian Pieter Hoffmann retweeted
🚩 When Polymarket or Kalshi says there's a 70% chance something will happen, should we believe it? Excited to share our new paper, just published in PNAS, in which we examined more than ONE MILLION forecasts from Polymarket, Kalshi, Manifold, and Metaculus, spanning 12 domains and forecasting horizons ranging from hours to years. The main finding is striking: Prediction markets and collective forecasting platforms are remarkably well calibrated. When they assign events a 70% probability, those events really do happen about 70% of the time. And this pattern holds surprisingly well across different platforms, domains, and forecasting horizons. But there's an important twist. When we looked more closely, we discovered systematic biases in some of the domains where forecasting matters most (wars, elections). For decades, psychologists have documented how poorly humans often reason about probability and uncertainty. Our findings offer an encouraging counterpoint: When judgments and information are aggregated, we can achieve a surprisingly accurate understanding of an uncertain future. That doesn't mean we can predict what will happen next with certainty. But it does mean that we can be remarkably good at estimating how uncertain the future really is. This work was a great collaboration. The data for this project was meticulously collected for years by Justin Dickerson, the project was led by Hilla Shinitzky and Maayan Peer, with @mattansb leading the analyses. 📄 Read the paper: pnas.org/doi/10.1073/pnas.26… #Forecasting #Polymarket #Kalshi #DecisionScience #PNAS
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Christian Pieter Hoffmann retweeted
France currently experiences large-scale rioting, mostly by (former) immigrants. Such events are often treated as isolated incidents. They are not. As I show here, immigration-related riots are becoming increasingly frequent and intense over time: laurenzguenther.substack.com…
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„Given the very weak relationships between SMU and the severity of anxiety and depression symptoms, SMU is unlikely to account for the contemporary youth mental health crisis.“ bpspsychub.onlinelibrary.wil…
First meta-analysis of the most authoritative studies: Adolescents' use of social media accounts for less than 1% of their subsequent symptoms of depression and anxiety. Most of the empirical investigations into social media use and mental health symptoms have utilized cross-sectional designs or have shown small effects, leading to scepticism in the field. More conclusive evidence could be synthesized from the full range of more robust longitudinal and experimental designs. Experimental designs are required to draw conclusions regarding causal relationships. Longitudinal designs afford conclusions regarding the direction of effects over time. To the best of our knowledge, this is the first review [and meta-analysis] to comprehensively synthesize longitudinal and experimental evidence on the association between time and frequency of social media use and mental health symptoms. We identified a considerably higher number of longitudinal papers than in a previous review. The key findings of this review and meta-analyses were that the relationships effects between time and frequency of social media use and depression and anxiety symptoms were statistically significant but relatively weak The time spent by young people using social media accounts for less than 1% of their subsequent symptoms of depression and anxiety. There is no evidence that this effect increases as age decreases. Reducing time spent on social media by young people is unlikely to be effective in preventing the worsening of their symptoms of depression and anxiety. Given the very weak relationships between social media use and the severity of anxiety and depression symptoms, social media use is unlikely to account for the contemporary youth mental health crisis. In relation to policy implications, a relationship between duration and frequency of social media use on subsequent anxiety and depression is not a solid basis for the rationale for age-related legal restrictions on social media.
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Christian Pieter Hoffmann retweeted
Liberals and conservatives behave differently in everyday life--conservatives seem to be out with others at lot more while liberals stay home and doomscroll. This study analyzed activity using smartphones to track college students and found that conservatives were more likely to be at parties, noisy places, fraternities and religious facilities. Liberals were at home, resting, doing chores, and browsing social media. This helps explain why conservatives are, on average, happier than liberals. The behavioral differences were small but robust, not accounted for by other plausible factors (e.g., demographics), and most pronounced in the leisure domain. psycnet.apa.org/fulltext/202…
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Christian Pieter Hoffmann retweeted
If the trend holds, academic journals will soon be receiving twice as many submissions per year as they did before the introduction of ChatGPT. AI will write them. AI will review them. And AI will read them.
“There’s going to be a flood of poor-quality research that the system is not equipped right now to handle.” Always has been dot jpg
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Christian Pieter Hoffmann retweeted
Bias against boys in education
"By four years of age, girls tend to think that boys are academically inferior to them… Teachers often see their female students as academically superior… even when aptitude tests show the opposite pattern for their classes." stevestewartwilliams.com/p/s…
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Christian Pieter Hoffmann retweeted
Cornell just produced a massive new report on higher education noting that companies have a “jarring” skepticism of higher ed thanks to a new generation of degree holders who lack key skills like handling uncertainty, compromising, and absorbing feedback. Faculty also report that incoming students, despite four years of undergraduate education, are “underdeveloped” in these relational or interpersonal skills. This is a serious crises in higher education and the report calls for a greater need for conflict-resolution training. We need to do a better job training our students to deal with these issues. These are traditionally the skills students developed in higher education. I loved college because it challenged me, sparked debate, and required me to grapple with complexity. This should be an essential part of college--inside and outside the classroom. chronicle.com/article/compan…
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Christian Pieter Hoffmann retweeted
Toxic workers impose a huge cost on organizations. Avoiding a toxic worker (or converting them to an average worker) provides far more benefits than retaining a superstar. Assuming that it is no more costly to avoid a toxic worker (or replace them with an average worker) than it is to find, hire, and retain a superstar, it is also more profitable to do the former over the latter. hbs.edu/ris/Publication%20Fi…
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Christian Pieter Hoffmann retweeted
1/ New paper led by @yuweichuai w/ @captaineco_fr @DG_Rand. In Nov 2025, X began showing where accounts actually operate from. We studied 8,200 politically engaged accounts claiming to be in the US; half were revealed to be elsewhere. What happened when the mismatch went public? 🧵 Pre-print: arxiv.org/abs/2609.25933
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Christian Pieter Hoffmann retweeted
With Claude I did a systematic literature review of misinformation prevalence, exposure, and concentration. There is a companion website that allows you to play with the data and signal me if an estimate is wrong or missing: altay-research.github.io/mis…
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Christian Pieter Hoffmann retweeted
"It's not that the public does not care about democracy. But Americans' understanding of the democratic way of doing politics is one of competitive parties, robust public participation, and open and free debate about the paths their communities should take. They see it differently from Democratic elites and progressive activists." Incredible new article: nationalaffairs.com/publicat…
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Christian Pieter Hoffmann retweeted
Does ingroup love lead to outgroup hate? NO! I often try to explain to people that identifying with ingroups does not necessarily lead to outgroup discrimination. I call this the "Myth of tribalism". A new paper provides strong and robust evidence for a positive relationship between ingroup and outgroup prosociality.! Across six datasets that span multiple domains of prosociality and group distinctions with 743,402 individuals in 121 societies, finds that people who are prosocial toward the ingroup also tend to be prosocial toward the outgroup. "The results offer an optimistic message for prosociality across group boundaries. When people are not made to choose between the ingroup and outgroup, they are generally prosocial toward both." Here is the new research: pnas.org/doi/10.1073/pnas.25… Here is an article I co-authored for The Atlantic on the Myth of Tribalism in 2022: theatlantic.com/ideas/archiv…
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Christian Pieter Hoffmann retweeted
People who really despair about their government and society often don't bother to protest, vote, or follow politics closely. They just check out. As a result, protests are not dominated by people with the most alienation, despair or who are least-well served by the system. It's people who still have faith in politics, institutions and their fellow citizens who take to the streets (this may also explain the asymmetry between left and right observed in the data). It's often people who have more free time and flexibility. And those who skew more towards the elite side of the socioeconomic spectrum.
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Christian Pieter Hoffmann retweeted
New paper out with @ElianaFattorini. @MassiBucchi, and Enzo Loner: “Weapon and poison? Framing disinformation in European Commission speeches, 2016–2024” We analyse how disinformation is framed in 238 speeches by European Commission in the last 10 years.
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Christian Pieter Hoffmann retweeted
🚨 It's finally out! 🚨 This is the big one. 100 cultures, 12,000 people, 108 researchers. Why people (and our most-used surveys) get collectivism wrong and how to fix it. Join me for a fun thread! 🧵 @NatureHumBehav nature.com/articles/s41562-0…
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Christian Pieter Hoffmann retweeted
Great to see this groundbreaking paper by colleagues at NHH and FAIR published. Required reading for anyone interested in fairness or inequality. One of many notable findings: Meritocratic fairness views are particularly prominent in richer Western societies.
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Impressive @ThadKousser @namalhotra et al. field experiment had few effects on election attitudes of TX conservatives despite exposure to "an average of 20 online videos, 18.5 cable TV videos, 23.9 display ads, 3 text messages & 3 postcards" - high-quality content crafted by pros
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Christian Pieter Hoffmann retweeted
Since many folks have already asked me about the shocking recent state election victory of the far right in Germany, here is a brief Labor Day FAQ with links. Isn't it really about economic deprivation or inequality? No lol. People vote for anti-immigration parties because they don't like immigration. Anti-immigration parties get more votes particularly when immigration is a nationally salient issue, as it is now: (goodauthority.org/news/good-…). Also see research by @JamesRDennison and @epkaufm. OK, but why does immigration matter so much now, and in one of the Saxonies of all places, where there are relatively few immigrants? Voters care about what they think immigration is doing to Germany as a whole. Their own local community or paycheck is only part of the picture. See more on sociotropic voting and immigration here: (goodauthority.org/news/good-…, goodauthority.org/news/can-t…). OK, but I thought the immigration numbers were going down—why doesn't salience go down too? Voters care about foreigners already living in the country and how immigration is managed. Germany, for instance, has hundreds of thousands of people legally required to leave who remain in the country, often because of administrative reasons—and voters don't like that. Public concerns are also thermostatic and need not track this year's flows. I discussed this in the US context here: (goodauthority.org/news/why-a…). So what should mainstream parties do to win voters back? As I argued after the AfD's breakthrough in Germany's 2025 election, they need to deliver visible improvements in immigration policy. People can support freer immigration (and not vote for anti-immigration parties) when they can see that it benefits their country, without needing experts to tell them so: (goodauthority.org/news/germa…). But doesn't accommodating the far right always hurt mainstream parties since voters go for the real thing? It depends, and the evidence is mixed. As @hannohilbig explains, a tougher immigration position can attract some voters but lose others. Voters also often (rightly!) don't find mainstream parties' new anti-immigration stances credible: (popularbydesign.org/p/why-do…). OK, but immigration is actually good after all—so why are all those people upset about it? Freer mobility is good on net, but Germany has adopted many costly immigration policies whose downsides have often been downplayed in mainstream debate. Turning qualified research findings into reassuring political messages makes sensible immigration policy harder: (faz.net/aktuell/karriere-hoc…). Also see our primer with @KelseyTuoc on why immigration in Germany and Western Europe is so much worse than in the US: (theargumentmag.com/p/why-ame…). I make the full argument behind these answers in my last book, In Our Interest. For a shorter read, check out The Uncomfortable Truths About Immigration here: (popularbydesign.org/p/the-un…).
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