Joop Adema

I am often told that public critique of published articles must also solve the issues found. I think this frequently enforced requirement hinders scientific self-correction.

Blog post:

mmmdata.io/posts/2025/0...

Although we believe this is the right conclusion, the note does not mention our comment or why the original results were "incorrect and not supported by the data".

Update #2, RETRACTED: 15 months after we (w @ollefolke.bsky.social and @johannarickne.bsky.social ) submitted the initial comment to the Journal, we've noticed the paper was ultimately retracted. Retraction note here: link.springer.com/article/10.1...

📣 Submit your paper to the Leibniz Open Science Day! I will be there to talk about our recent experience with replicating Ciacci (2024) about impacts of the Swedish legislation that banned sex purchases. Call for papers: www.zbw.eu/de/ueber-uns...

A warm welcome to @jopieboy.bsky.social ‪! 🌟 ‬‬
Thrilled to have him in the network! He researches labor economics and political economy of international migration.📊

🔍 His research: jopieadema.github.io
🔗 www.ifo.de/en/cesifo/ne...

📣Call for papers: 𝗖𝗘𝗠𝗜𝗥 𝗝𝘂𝗻𝗶𝗼𝗿 𝗘𝗰𝗼𝗻𝗼𝗺𝗶𝘀𝘁 𝗪𝗼𝗿𝗸𝘀𝗵𝗼𝗽 𝗼𝗻 𝗠𝗶𝗴𝗿𝗮𝘁𝗶𝗼𝗻 𝗥𝗲𝘀𝗲𝗮𝗿𝗰𝗵, 28 - 29 October 2025, Munich

Keynote Speaker: Jens Hainmueller (Stanford)

ℹ️ www.ifo.de/en/event/202...

👉 Submit by 30 June: app.oxfordabstracts.com/stages/78037...

@sebastianschirner.bsky.social @econmunich.bsky.social

My comment+code can be found here: jopieadema.github.io/replication/. It was desk rejected by AER:I on the grounds of not "meeting the high bar needed to justify publishing a comment" while acknowledging it's a "significant nuance to our understanding". I leave judgement to the reader.

Taking AJKs study at face value, it has large implications for policy makers: they can steer (refugee) migration by tuning benefits. My comment shows that these concerns are largely unwarranted. However, benefit cuts worsen outcomes of refugee children: shorturl.at/iMtTo

Another prediction of the welfare magnet hypothesis is that benefit cuts also predict an increase in the skill level of migrants. Using the EU LFS I find that lower benefits do NOT lower the skill levels of newly arriving migrants.

I re-analyze the case using an origin-specific approach, finding much smaller max. elasticity estimates: only 0.14 for stocks, 0.28 for inflows and 0.77 for asylum applications. However, the variability of refugee flows (esp. the 2015/2016 crisis) makes these estimates imprecise.

Beyond these concerns, there are many simultaneous policy changes, that typically become more restrictive when benefits decrease. Hence, any estimates from these reforms can only identifiy an UPPER bound of the effects of benefit changes.

e.g. DK received overproportionally many asylum seekers from Syria and Afghanistan in 2001, but total asylum flows from these countries to Europe decreased simultaneously with benefit cuts in 2002. I account for origin-specific shocks in my re-analysis below.

Third, AJKs second approach compares net non-EU migration to DK with other nordic countries in a synthetic control. However, they disregard the origin country composition of migration flows, which is consequential as (refugee) migration is strongly driven by origin country shocks.

This is driven by the age distribution of migrant residents in 2001, as many turned 30 just before 2002 but much fewer after. As they estimate effects relative to a counterfactual based on a pre-2002 trend, the large increase in migrants turning 30 in the 1990s strongly inflates the effect.

Second, they calculate net difference in the annual stock of non-EU migrants migration flows aged 30+ (bc of other reform). This captures in- and outflows, but also existing migrants turning 30 (+), strongly overestimating net migration and effect size wrt differences in net flows.

First, AJK report a poorly defined net migration elasticity wrt benefits of 1.3. If net migration is negative, it's undefined. If small but positive, the elasticity explodes. This sensitivity limits the applicability: it is incomparable to usual stock migration elasticities and can't inform policy.

Reading their paper, I detected three consequential issues. I reanalyse the setting and test an additional prediction of the welfare magnet hypothesis. I hope that my concerns below improve future studies of the impact of policies on migration flows.

Denmark strongly reduced benefits for non-EU migrants in 2002, bringing benefits back up in 2012 and re-introducing low benefits in 2015 again. AJK study this by (1) comparing non-EU migration to EU-15 migration to Denmark and (2) non-EU migration to Denmark to that to other Nordic countries.

🧵Replication: Can refugee flows be lowered by reducing welfare? Agersnap et al. (2020, AER:I) study this in Denmark, reporting lower benefits strongly reduce migration flows. I reanalyze this paper, finding a much more nuanced result.

📣 Join us for the annual Richard Löwenthal Lecture on
"Return and Return Intentions of Ukrainian Refugees" by Prof. Panu Poutvaara. 🇺🇦

📅 11.06.2025, 4 PM
📍 Hörsaal A, OEI, Garystr. 55, 14195 Berlin

🔗 tinyurl.com/LOE25

@freieuniversitaet.bsky.social

A more important non-econ argument: the majority of aviation's climate impact is due to other factors than CO2, which are NOT sccounted for in the current ETS (www.sciencedirect.com/science/arti...). I think we could say with confidence that under the current ETS it is still better to go by train.

To calc the marginal emissions of a intra-EU flight is very hard; you need to know who is at the margin and the carbon intensity of their alternatives. Your argument about the diesel trains is not relevant -- very few 800km trips in Europe largely rely on diesel-locs.

I heard this argument before, but it's more complicated. Flying raises the carbon price and marginal actors change bahavior. If this actor switches from grey to green tech, that's great. However, there is carbon leakage; if production leaves the EU or if a tourist goes by car instead of plane.

📢 Come work with us!

🏛️ Faculty of Economics & Statistics, UIBK @econstatuibk.bsky.social‬ @uniinnsbruck.bsky.social‬

‼️ Three job openings for Full Professor positions

- Data Science

- Microeconomics

- Behavioral Economics

Please share! #datascience #economics

www.uibk.ac.at/de/info-beru...

𝗖𝗘𝗦𝗶𝗳𝗼 𝗔𝗿𝗲𝗮 𝗖𝗼𝗻𝗳𝗲𝗿𝗲𝗻𝗰𝗲 𝗟𝗮𝗯𝗼𝗿 𝗘𝗰𝗼𝗻𝗼𝗺𝗶𝗰𝘀, oganized by 𝗚𝗼𝗿𝗱𝗼𝗻 𝗗𝗮𝗵𝗹 is ending. 👏to @jopieboy.bsky.social on winning the Affiliate Award. Great presentations by @ursina.bsky.social @aadukia.bsky.social, @martinauccioli.bsky.social. 🙏 A special thanks to 𝗔𝗻𝗻𝗮 𝗔𝗶𝘇𝗲𝗿 for her keynote and to all presenters!

We are looking to hire post-doc interested in working on migration, citizenship, and diaspora. Come join us in Münster! Generous contract + no teaching for 2 years.

Many details and link to job add here:

sites.google.com/site/tnhalbe...

Please PM me incase you have questions!

Update: We submitted the comment to the Journal of Population Economics, and today we got a desk reject with this motivation. However, we do not know their conclusion about the main results and why the paper was not retracted. Clearly, they do not hold. 1/4

A re-analysis of Ciacci's (2024) "Banning the purchase of sex increases cases of rape: Evidence from Sweden" Journal of Population Economics reveals major issues. A year ago, reproducers Adema, Folke, and Rickne found coding errors driving the paper's key results. Let's unpack this in a 🧵

🚨 REPLICATION REPORT UPDATE: One year ago, a tweet by John Holbein alerted me, @ollefolke.bsky.social, and @jopieboy.bsky.social to a paper with a shocking result about Sweden’s law criminalizing the purchase of sex.🧵

Anomalies & data problems are found in the Hungarian EU SILC income data from around year 2017. It is very likely that the data was manipulated to decrease the poverty rate.

Annamaria Tatrai and Andras Gabos conducted a very thorough investigation of the issue: www.valaszonline.hu/2025/04/01/e...