About Me

I am an associate professor (Docens) at the Institute of Data Analytics and Information Science at Corvinus University of Budapest and a research fellow at the Institute of Economics of the Centre for Economic and Regional Studies in Hungary. I am also affiliated with the Complexity Science Hub Vienna. I study social, technical, and economic networks and their effects on society using methods of data and network science. Recently I am especially interested in the social and economic impact of software, especially open source and AI.

News and Updates

- My proposal "The Economic Geography of Digital Innovation" has been funded by the Hungarian Research Funding Agency. I'll be hiring a postdoc soon - get in touch!
- We are launching a new 1 year MSc program in Social Data Science at Corvinus, starting Fall 2025. [Link]
- New paper with Maria del Rio-Chanona and Nadzeya Laurentsyeva: "Large language models reduce public knowledge sharing on online Q&A platforms". [Link].
- My paper on Russian software developer braindrain was mentioned in Science.

Selected Publications

For a full listing, see my [Scholar page].

Digital Traces of Brain Drain: Developers during the Russian Invasion of Ukraine [Link]

Johannes Wachs
EPJ Data Science, 2023.
Press: [Handelsblatt - DE], [Novaya Gazeta - RU], [Bloomberg - US], [WSJ - US], [New Scientist - US], [Moscow Times - RU], [Fonetech - CZ], [Tygodnik Powszechny - PL], [hwsw - HU]
Podcast (Hungarian): [Kraftie].

The Geography of Open Source Software: Evidence from GitHub [Link]

Johannes Wachs, Mariusz Nitecki, William Schueller, and Axel Polleres
Technological Forecasting and Social Change, 2022.
Presentation at OFE: [Link]

Evolving collaboration, dependencies, and use in the Rust Open Source Software ecosystem [Link]

William Schueller, Johannes Wachs, Vito D. P. Servedio, Stefan Thurner, & Vittorio Loreto
Nature Scientific Data, 2022.

Agency independence, campaign contributions, and favouritism in US federal government contracting [Link]

Mihaly Fazekas, Romain Ferrali, and Johannes Wachs
Journal of Public Administration Research and Theory, 2022.

How Gamification Affects Software Developers: Cautionary Evidence from a Natural Experiment on GitHub. [Link]

Lukas Moldon, Markus Strohmaier, and Johannes Wachs
IEEE/ACM 43rd International Conference on Software Engineering (ICSE), 2021.
Summary on YouTube: [Link]

Does crowdfunding really foster innovation? Evidence from the board game industry. [Link]

Johannes Wachs and Balázs Vedres
Technological Forecasting and Social Change, 2021.
Podcast: [Link]

Inequality is rising where social network segregation interacts with urban topology. [Link]

Gergő Tóth, Johannes Wachs, Riccardo Di Clemente, Ákos Jakobi, Bence Ságvári, János Kertész, and Balázs Lengyel
Nature Communications, 2021.
Press:
---- Der Standard (AT): Wie das Stadtbild Ungleichheiten verstärkt.
---- le Scienze (IT): Il peso della geografia urbana sulle disparità tra cittadini.
---- 24.hu (HU): Bár az iWiW halott, az adatbázisából kutatják, miként csökkenthetők az egyenlőtlenségek.
---- UPI (EN): For more equitable cities, researchers say to keep social networks intact.
---- Qubit (HU): A rég halott iWiW kincset érő adatain mutatták ki, hol nőhet az egyenlőtlenség Magyarországon.

Writer movements between news outlets reflect political polarization in media. [Link]

Nick Hagar, Johannes Wachs, and Emőke-Ágnes Horvát
New Media & Society, 2021.
Press:
---- Der Tagesspiegel (DE): Journalistische Filterblasen.
---- Niskanen Center Science of Politics Podcast (EN): How the Media Economy Drives Political News.
---- RQ1 (EN): How the pandemic (sort of) changed our news habits.

A network approach to cartel detection in public auction markets. [Link]

Johannes Wachs and János Kertész
Scientific Reports, 2019.

Gender Differences in Participation and Reward on Stack Overflow. [Link]

Anna May, Johannes Wachs, and Aniko Hannak
Empirical Software Engineering, 2019.

Social capital predicts corruption risk in towns. [Link]

Johannes Wachs, Taha Yasseri, Balázs Lengyel, and János Kertész
Royal Society Open Science, 2019.

Policy Papers

Gender in European public procurement: Extent, distribution, and impacts. [Link]

Mihaly Fazekas, Yuliia Kazmina, and Johannes Wachs
European Bank for Reconstruction and Development (EBRD) Research Paper, 2020 .

Grants and Prizes

2024-2027: Building Blocks of the Digital Economy, supported by the Hungarian Research Funding Agency (OTKA-FK)
2021-2024: Crisis Response and Intervention Supported by Semantic Data Pooling (CRISP), supported by the FFG's "ICT of the Future" program
October 2020: Our team won the IMF Anti-Corruption Challenge!
2020-2021: Geography of Open Source Software, supported by the City of Vienna-WU Jubilee Fund
2020-2021: Data Set Re-Use, supported by the WU Projects fund

Teaching and Supervision

PhD Students:
Hannah Schuster at WU Wien/CSH, with Axel Polleres. 2021-
Brigi Németh at Corvinus University of Budapest. 2023-

Applied Data Science: Computational Social Science, Vienna University of Economics and Business, multiple 2020-2023
Research Praktikum, RWTH Aachen Winter Semester 2019-20
Social Data Science, course instructor, RWTH Aachen Winter Semester 2019-20
Social Networks, course instructor, RWTH Aachen Summer Semester 2019
Using Big Data for social science research, teaching assistant, CEU Spring 2017
Data Mining, course instructor, AIT Fall 2016
Scientific Python, teaching assistant, CEU Fall 2016, 2017

Selected Student Theses:
--- Philip Grawatsch-Pollhammer, Collaborative Networks in Creative Industries: The Case of Tatort. Bachelor's Thesis, WU Wien, 2022. [PDF]
--- Jeremias Brändle, Analysing the Impact of Corruption on Innovation Performance in European Regions. Bachelor's Thesis, WU Wien, 2021. [PDF]
--- Lukas Moldon, Sending signals in open source: Evidence from a natural experiment. Bachelor's Thesis, RWTH Aachen, 2020. [PDF]
--- Timur Bachschi, From Asking to Answering: Social and Structural Aspects of Contributing to Stack Overflow. Bachelor's Thesis, RWTH Aachen, 2020. [PDF]

Education

PhD Network Science, summa cum laude, Central European University (2019)
MS Applied Mathematics with distinction, Central European University (2012)
BS Mathematics, BS Economics, cum laude, Tulane University (2009)

Contact

johanneswachs at gmail dot com