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Achim Ahrens

@aahrens.bsky.social

636 followers 1.1K following 13 posts

Senior Researcher, @immigrationlab.bsky.social, ETH Zurich | AP CERGE-EI from Sept '25 | Software: statalasso.github.io | Applied econometrics, ML, migration, labour | achimahrens.de

Posts Replies Media

Achim Ahrens @aahrens.bsky.social · 05/04/2025

If your main problem is not many controls but many proxies of public transit, then I would bunch them together into 1 variable using PCA or factor analysis, as Peter suggests.

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Achim Ahrens @aahrens.bsky.social · 05/04/2025

If lasso, PDS-lasso is what you want to do. You need to consider both the outcome and treatment equation. Even better: use DDML; then, you can relax sparsity and consider other learners. Stata packages: pdslasso, ddml. R: ddml, DoubleML, hdm. statalasso.github.io thomaswiemann.com/ddml/

statalasso.github.io

Introduction

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Reposted by Achim Ahrens

Our World in Data @ourworldindata.org · 08/11/2024

See how immigration numbers compare across countries: ourworldindata.org/explorers/migrat…

ourworldindata.org

Migration, Refugees, and Asylum Seekers Data Explorer

Explore the migration of people across the world.

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Achim Ahrens @aahrens.bsky.social · 27/11/2024

could you add me?

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Achim Ahrens @aahrens.bsky.social · 27/11/2024

Many,many thanks to: @danielauer.bsky.social, @andreasbeerli.bsky.social, Alessandra Stambi-Bombelli, Marine Casalis, Dominik Hangartner, Chris Hansen, Selina Kurer, Stefanie Kurt, Rodrigo Sanchez, @markeschaffer.bsky.social, Michael Siegenthaler, Michaela Slotwinski, Alois Stutzer, Thomas Wiemann.

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Achim Ahrens @aahrens.bsky.social · 27/11/2024

5 - Focusing again on Switzerland, we find that higher social assistance reduces criminal charges, especially for petty crimes and drug offenses. WP: papers.ssrn.com/sol3/papers....

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Achim Ahrens @aahrens.bsky.social · 27/11/2024

4 - What is the effect of cash assistance on the socio-economic integration of vulnerable Venezuelans living in Peru? We evaluate a cash-based intervention implemented by IOM and partners. Published World Development: doi.org/10.1016/j.wo...

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Achim Ahrens @aahrens.bsky.social · 27/11/2024

3 - Double Machine Learning (DML) has become hugely popular for estimating structural parameters using ML. We highlight the risk of employing ill-suited machine learners and show the benefits of pairing DML with model averaging. With R & Stata software. Accepted @ JAE: arxiv.org/pdf/2401.01645

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Achim Ahrens @aahrens.bsky.social · 27/11/2024

2 - Linking the labor market restrictions faced by refugees in Switzerland to the literature on outside options, we find that restricting refugees' outside options reduces job-to-job mobility and refugees' wages, widening the wage gap to natives in similar jobs. WP: osf.io/preprints/so...

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Achim Ahrens @aahrens.bsky.social · 27/11/2024

1 - How can we encourage eligible immigrants to naturalize? We design and field a policy tree for a letter-based information campaign. The policy tree optimally selects between alternative encouragement letters. Forthcoming JAE: doi.org/10.1002/jae....

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Achim Ahrens @aahrens.bsky.social · 27/11/2024

Now that we are (almost) all here and the year is coming to an end, it's a good time for a personal annual recap. 🧵 A thread of 5 papers. Keep reading for labor, migration, applied econometrics, double machine learning. (Coincidentally, I am looking for a job. #Econbsky #EconSky)

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Achim Ahrens @aahrens.bsky.social · 21/11/2024

Could you add me? Thanks for doing this

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Achim Ahrens @aahrens.bsky.social · 07/01/2024

pystacked is joint work with @markeschaffer.bsky.social and Chris Hansen. For more info, see statalasso.github.io/docs/pystack....

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Achim Ahrens @aahrens.bsky.social · 07/01/2024

Our open-access article introducing -pystacked- for stacking and machine learning in Stata is now available online. doi.org/10.1177/1536... Watch our short video to see what -pystacked- can do. youtu.be/MVAlpcfIfxA

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