New NERDS paper: Gender inequality in cycling

Revealing the determinants of gender inequality in urban cycling with large-scale data, by A. Battiston, L. Napoli, P. Bajardi, A. Panisson, A. Perotti, M. Szell & R. Schifanella, published in EPJ Data Science

The uptake of cycling in today’s cities is especially low for women: there is a largely unexplained, persistent gender gap in cycling. To understand the determinants of this gender gap in cycling at scale, here we use massive, automatically-collected data from the tracking application Strava on outdoor cycling for 61 cities across the United States, the United Kingdom, Italy and the Benelux area. While Strava data is particularly well-suited to describe the behavior of regular cyclists and its generalizability to occasional cyclists requires further investigation, the size of these data and their characteristics represent an unprecedented opportunity for the literature on cycling. Leveraging the associated gender and usage information, we first quantify the emerging gender gap in recreational cycling at city-level. A comparison of cycling rates of women across cities within similar geographical areas—where the penetration of Strava is assumed to be comparable—unveils a broad range of gender gaps. On a macroscopic level, we link this heterogeneity to a variety of urban indicators and provide evidence for traditional hypotheses on the determinants of the gender-cycling-gap. We find a positive association between female cycling rate and urban road safety. On a microscopic level, we identify female preferences for street-specific features in the city of New York. Assuming that the determinants of the gender-cycling-gap are similar across regular and occasional cyclists, our study suggests that enhancing the quality of the dedicated cycling infrastructure may be a way to make urban environments more accessible for women, thereby making urban transport more sustainable for everyone.

NERDS/CSH-organized workshop on sustainable mobility in Vienna

Last week we, Michael Szell and Anastassia Vybornova, together with Rafael Prieto Curiel from Complexity Science Hub Vienna, held a workshop on sustainable mobility in Vienna, Austria, featuring some of the top local experts on the topic: Vienna’s cycling coordinator Martin Blum, and the researchers Anita Graser, Barbara Laa, Ulrich Leth.

The event featured 7 talks (2 from NERDS) and many thought-provoking discussions, see a nice summary here:

The workshop covered the following aspects:

Why are politicians so reluctant to invest into bicycle infrastructure and pedestrianization given it is the most efficient investment towards sustainable and livable cities? What are the technical and political bottlenecks that keep society in the stranglehold of car dependency, and what are the implications of sustained delay? Which data are we missing, how should we grow network infrastructure, and how to speed up the sluggish political process? The climate crisis demands pressing answers, which we explore here with state-of-the-art insights in Data/Network/Complexity Science and Urban Planning.

This workshop brings together researchers and policymakers from Vienna and Copenhagen who work on understanding the best pathways towards sustainable mobility with focus on cycling, or who are developing tools/methods supporting that aim. Our speakers will cover: Mobility and infrastructure data quality, bicycle network planning, politics & activism, systemic complexity approaches.

Tiago Cunha leaves NERDS

On April 1st our postdoc Tiago Cunha has sadly left our research group to industry, going from applying his data science knowledge at Novo Nordisk. Tiago has been the first NERDS postdoc, spending more than 3 years in the group. We had a great time together and he was a pivotal member of the group, both from a scientific and a social point of view. We wish him all the best for his future!

Two new PhD calls (Application deadline: April 1st)

We have two PhD positions open! Both salary and working conditions are excellent. Our group is a down-to-earth and fun place to be. Copenhagen is often named the best city in the world to live in, and for good reasons. It’s world-renowned for food, beer, art, music, architecture, the Scandinavian “hygge”, and much more. In Denmark, parental leave is generous, and child-care is excellent and cheap. See the two positions below, and feel free to apply if you fit (you can apply to both).

Position number 1

This PhD will work under the supervision of Roberta Sinatra, will be employed at SODAS (University of Copenhagen), and will have affiliations with the NEtwoRks, Data, and Society (NERDS) group at IT University of Copenhagen and with the pioneer center for AI. The topic is on Science of Science and Algorithmic fairness. The PhD position is part of a large project, funded by the Villum Foundation, aimed to uncover the bias mechanisms that drive scientific impact, and to use them to create fair algorithms. The project will involve the analysis of large-scale datasets, running controlled experiments, and modelling social dynamics in science. Our priority is to attract technically strong researchers who are interested in asking bold, new questions with data. The team executing the project is composed of the PI, two postdocs, and one PhD student. 

Apply here by April 1st 2023:
Contact Roberta Sinatra ( if you have any questions

Position number 2

This PhD will work under the supervision of Vedran Sekara, with co-supervisor Roberta Sinatra, will be employed in the NEtwoRks, Data, and Society (NERDS) group at IT University of Copenhagen, and will have an affiliation with the pioneer center for AI. The PhD position is funded by the pioneer center for AI and the topic is predictability of social systems. Indeed, with the rise of algorithmic decision-making and with automated systems mediating an increasingly larger part of our social, cultural, economic, and political interactions, it is vital to understand the limits of prediction and when predictive accuracies fall short of expectations. The overreaching goal of this proposal is to develop an empirical and theoretical understanding of predictability in social networks and human mobility. Are prediction limits determined by the size and bias present in datasets, the scale of computational power, or are there fundamental limits to prediction?

Apply here by April 1st 2023, make sure to specify the project (last one listed):
Contact Vedran Sekara ( if you have any questions.


Welcome Iraklis to NERDS!

Iraklis Moutidis joins NERDS today as a postdoctoral researcher. He will work with Luca Aiello on the COCOONS project. Iraklis got his PhD in Computer Science from the University of Exeter (UK) and he works at the intersection of Machine Learning and Social Network Analysis. Welcome, Iraklis!

New NERDS paper: Quantifying Ideological Polarization on a Network

Today we published a paper on ideological polarization. Special congrats to Marilena for this being her first paper!

Quantifying Ideological Polarization on a Network Using Generalized Euclidean Distance, by M. Hohmann, K. Devriendt, M. Coscia, published in Science Advances

An intensely debated topic is whether political polarization on social media is on the rise. We can investigate this question only if we can quantify polarization, by taking into account how extreme the opinions of the people are, how much they organize into echo chambers, and how these echo chambers organize in the network. Current polarization estimates are insensitive to at least one of these factors: they cannot conclusively clarify the opening question. Here, we propose a measure of ideological polarization which can capture the factors we listed. The measure is based on the Generalized Euclidean (GE) distance, which estimates the distance between two vectors on a network, e.g., representing people’s opinion. This measure can fill the methodological gap left by the state of the art, and leads to useful insights when applied to real-world debates happening on social media and to data from the US Congress.

NERDS growth in 2023

Happy new year! We are excited to report many new faces at NERDS, on one hand due to an increased number of interns joining, and on the other hand through Luca’s Carlsberg grant which now starts to kick in.

With Jan 1st, joining us is the new long-term member Arianna Pera as PhD student, who recently got her master degree at Universita Bicocca in Italy. She will work in the area of computational social science, and especially with topics related to coordination. At the same time, we have postdoc Alessia Antelmi from University of Salerno in Italy. She will be with us for 6 months working on higher-order interactions applied to online conversations. Further, Lucio La Cava is a PhD student at the University of Calabria in Italy. He will visit us for three months, working at the intersection of collective coordination and Web3. A future PhD student will be Anders Giovanni Møller, who is currently still a Masterstudent here at ITU. He will start his PhD with us in June but he is already around before then. His main focus is NLP and he will work at the intersection of NLP and social network analysis. Apart from this new batch of 2023 people, we have two more master student interns, Henrik Wolf and Carlson Büth, who are visiting us since fall from Germany, Dresden and Münster, respectively.

All of these excellent new people bring more life to our group – they also have almost filled up all our tables in our large 3F29 section and we might need to look for new space soon. We are happy about all the buzz and intellectual cross-pollination going on!

Our interns are happy and becoming numerous due to our group’s and university’s efforts to be welcoming to visitors. To quote our Positions page:

We are very open to welcome self-funded research visitors if the topic of collaboration makes sense – for such inquiries please contact us via email. If you need funding let us know too: There might be / we might know of possibilities of third-party or internal funding.

Stonks 📈

Arianna Pera has joined NERDS

We are thrilled to welcome Arianna Pera to NERDS!

Arianna will be a PhD student for 3 years, working with Luca Aiello on the Carlsbergfondet project COCOONS on fostering collective cooperation in online social media to tackle societal dilemmas. Arianna recently got her MSc in Data Science from Università degli Studi di Milano-Bicocca. She will work at the intersection of Network Science and Natural Language Processing. Welcome, Arianna!



New NERDS paper: Multidimensional tie strength and economic development

Multidimensional tie strength and economic development, by L.M. Aiello, S. Joglekar, and D. Quercia, published in Scientific Reports

For decades, Granovetter’s tie strength has been quantified using the frequency of interaction. Yet, frequency does not reflect Granovetter’s initial conception of strength, which is a mix of social dimensions including exchnage of knowledge and provision of support. We used Natural Language Processing to quantify whether text messages convey expressions of knowledge or support, and applied it to a large conversation network from of Reddit users resident in the United States. Borrowing a classic experimental setup, we tested whether the diversity of social connections of Reddit users resident in a specific US state would correlate with the economic opportunities in that state (estimated with GDP per capita). We found that the combination of diversity calculated on the knowledge and support networks correlates much more strongly with GDP than diversity calculated on a network weighted with interaction frequency (R2=0.62 vs. R2=0.30). We also found that the two types of ties differ in their geographical span. Knowledge ties are long-distance (i.e., connecting people living in far-away states), support ties are mostly created among people living close by. Read more in this blogpost.

New NERDS paper: Computational Desire Line Analysis of Cyclists

We published another urban planning paper:

  1. Computational Desire Line Analysis of Cyclists on the Dybbølsbro Intersection in Copenhagen, by S.M. Breum, B. Kostic, and M. Szell, published in Transport Findings

    To improve intersection planning, here we develop a computational method to detect cyclist trajectories from video recordings and apply it to the Dybbølsbro intersection in Copenhagen, Denmark. In one hour of footage we find hundreds of trajectories that contradict the design, explainable by the desire for straightforward, uninterrupted travel largely not provided by the intersection. This neglect and the prioritization of vehicular traffic highlight opportunities for improving Danish intersection design.