New NERDS paper: Urban segregation and random walks

We have a new NERDS paper out by our Postdoc Sandro Sousa. This paper marks his main work from his PhD at Queen Mary University of London, published now:

  1. Quantifying ethnic segregation in cities through random walks by S. Sousa and V. Nicosia, published in Nature Communications

    We propose here a family of non-parametric measures for spatial distributions, based on the statistics of the trajectories of random walks on graphs associated to a spatial system. These quantities provide a consistent estimation of segregation in synthetic spatial patterns, and we use them to analyse the ethnic segregation of metropolitan areas in the US and the UK. We show that the spatial diversity of ethnic distributions, as measured through diffusion on graphs, allow us to compare the ethnic segregation of urban areas having different size, shape, or peculiar microscopic characteristics, and exhibits a strong association with socio-economic deprivation.

Roberta Sinatra becomes Full Professor at Copenhagen University (SODAS)

Today one of our group’s founders, Roberta Sinatra, became full professor, assuming a new position at the Copenhagen Center for Social Data Science (SODAS) at Copenhagen University (KU): https://sodas.ku.dk/

Congratulations to Roberta – very well deserved!

Having been promoted from assistant professor to associate professor just two years ago, Roberta’s new full professor position hallmarks a stellar career. At SODAS Roberta will be steering the center, head its new ethics committee, and be involved in the center’s new MSc programme in Social Data Science, among other things.

Roberta will have a new main workplace at KU’s city campus (Øster Farimagsgade 5), but luckily she will remain affiliated with us NERDS, so we will keep enjoying her expertise and occasional company in the future. To accommodate this change, Michael Szell will take over her role of group coordinator.

We congratulate Roberta and look forward to many fruitful collaborations with KU!

Two new NERDS papers: NFT price dynamics and Online originality

Two new NERDS papers are out – this time both in Scientific Reports:

  1. Heterogeneous rarity patterns drive price dynamics in NFT collections, by A. Mekacher, A. Bracci, M. Nadini, M. Martino, L. Alessandretti, L.M. Aiello & A. Baronchelli, published in Scientific ReportsWe quantify Non Fungible Token (NFT) rarity and investigate how it impacts market behaviour. We show that, on average, rarer NFTs: (i) sell for higher prices, (ii) are traded less frequently, (iii) guarantee higher returns on investment, and (iv) are less risky, i.e., less prone to yield negative returns. The dataset used for the work has been presented as part of a beautiful art exhibition at the MEET Digital Culture Center in Milano.
  2. Posts on central websites need less originality to be noticed, by M. Coscia and C. Vandeweerdt, published in Scientific Reports
    In this paper we study how originality and centrality interact in a nontrivial way, which might explain why originality by itself is not a good predictor of success. We collected data from Reddit on users sharing hyperlinks. We estimated the originality of each post title and the centrality of the website hosting the shared link. We show that the interaction effect exists: if users share content from a central website, originality no longer increases the odds of receiving at least one upvote.
    See more info in Michele’s blogpost: https://www.michelecoscia.com/?p=2205

Two NERDS papers out: Social media flagging and Multimodal transport networks

We published two more papers over the last weeks!

    1. A potential mechanism for low tolerance feedback loops in social media flagging systems, by C.J. Westermann and M. Coscia, published in PLOS ONE

      In this paper we simulate a scenario in which users on one side of the polarity spectrum have different tolerance levels for the opinions of the other side. We create a model based on some assumptions about online news consumption, including echo chambers, selective exposure, and confirmation bias. When studying a model of social media flagging, we see that intolerance is attractive: news sources are nudged to move their polarity to the side of the intolerant users.
      See more info on Michele’s blogpost: https://www.michelecoscia.com/?p=2179

    2. Multimodal urban mobility and multilayer transport networks, by L. Alessandretti, L.G. Natera Orozco, M. Saberi, M. Szell, F. Battiston, published in Environment and Planning B

      This is a comprehensive overview of the emerging research areas of multilayer transport networks and multimodal urban mobility, focusing on contributions from the interdisciplinary fields of complex systems, urban data science, and science of cities. First, we present an introduction to the mathematical framework of multilayer networks. We apply it to survey models of multimodal infrastructures, as well as measures used for quantifying multimodality, and related empirical findings. We review modelling approaches and observational evidence in multimodal mobility and public transport system dynamics, focusing on integrated real-world mobility patterns, where individuals navigate urban systems using different transport modes. We then provide a survey of freely available datasets on multimodal infrastructure and mobility, and a list of open source tools for their analyses. Finally, we conclude with an outlook on open research questions and promising directions for future research.

IC2S2 2023 in Copenhagen!

Copenhagen will host the 9th edition of the International Conference of Computational Social Science (IC2S2) in July 2023, brought here by NERDS & Co!

IC²S² is the premier annual meeting bringing together researchers from different disciplines interested in using computational and data-intensive methods to address societally relevant problems.

The event will be organized jointly between the IT University of Copenhagen (ITU), the Technical University of Denmark (DTU), and the University of Copenhagen (KU). NERDS will have a crucial role in the organization: Luca Aiello will be General Co-Chair, Roberta Sinatra will be Program Co-Chair, and NERDS will be heavily involved in organization and connecting conference participants. The event will take place at the Maersk Tower, a fabulous venue in the heart of the city.

The Maersk Tower in Copenhagen

All previous editions of the conference have been a great success, with hundreds of participants, and we’ll work hard to go above and beyond with the next edition. The conference will feature around 10 keynote talks, 6 tutorials, 200+ contributed presentations, and a 3-day poster session.

Busy attendees during the last two in-presence conferences in Amsterdam and Chicago.

We’re looking forward to welcoming you in Copenhagen next year!

NERDS is Research Environment of the Year 2022

The Danish Young Academy of the Royal Danish Academy of Sciences and Letters has chosen out of 62 nominated research environments our research group NEtwoRks, Data, and Society (NERDS) as

Research Environment of the Year 2022

The Academy ceremoniously awarded the title and a prize on June 1st to our group’s nominators, Anastassia and Tiago, who motivated their nomination as follows:

In our group, we openly talk about the struggles of academia, such as stress, high pressure, competitiveness, gender, and racial biases – and about the struggles of our personal lives, such as balancing care duties and research work. As young academics, NERDS is the best company that we could wish for: individuals with curious minds, supporting each other in their personal quests for knowledge and for the betterment of society, which is what ultimately drives us all.

See the Danish Young Academy’s explanation here: http://www.youngacademy.dk/Aktiviteter/Forskningsmiljopris.aspx
Among other points, they write:

In just 3 years, NERDS has managed to create an exemplary academic environment and unity. The group shows that seniority and large center grants are not necessarily the only prerequisites for a good research environment.  

Given this title, we have been asked about our “secret”. Having experienced our fair share of abusive environments, these seem some reasonable guidelines:

  1. Be nice to each other. Corollary: Surround yourself with the right people, and be very sure to not let toxic people into your environment.
  2. Psychological safety is most important. Mistakes are expected, especially in science. It is normal to get stuck in the cloud and we must support each other through it. Disagreements are expected too, and a diversity of perspectives helps resolve them amicably.
  3. Avoid having one boss. Research groups where one person is in power invites abuse. Keep inequalities to a minimum, make important decisions together.
  4. Make sure people have all the freedom to mingle and build up a support network. This will make them strong and protect them from academia’s harassment networks.

Thank you Anastassia and Tiago for the nomination, thank you all NERDS for being so excellent to each other, thank you to our department head Peter Sestoft for the amazing support and efforts to create a great as possible environment on the department level, and cheers to the Danish Young Academy! 🍸

We will do our best to continue living up to this honorable title.

Bojan Kostic has left NERDS

Today our postdoc Bojan Kostic has sadly left our research group to industry, going from applying his computer vision know-how for desire line analysis, to playing with trains (data) in a data science company. We had a great time together with Bojan, he was a true enrichment to our group, both from a scientific and a social point of view, and we wish him all the best for his future!

NERDS at ISI Foundation in Turin

For the last week, several of us NERDS have been visiting Turin, Italy, and our friends at ISI Foundation for a truly hearty scientific and social interchange.

Yesterday, ISI held a workshop in which our research groups exchanged know-how and learned from each other about all things data science, and how to apply it to the social good. We learned about topics as diverse as AI-based pdf crawlers, algorithmic bias, bicycle networks, or how to survive in a big research group.

Here some visual impressions of the workshop:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

And of course, also many extracurricular activities were to be had!

 

 

 

 

 

 

 

 

 

We are having a great time in Turin but every party must come to an end, and most of us will leave back to our home in Denmark soon. Some of us are more lucky though and will stay a few more weeks, keeping enjoying this amazing city with our wonderful friends.

Two NERDS papers out: Road User Safety and Growing Bicycle Networks

We just published two more papers! Both are on the topic of sustainable mobility:

    1. Growing urban bicycle networks, by M. Szell, S. Mimar, T. Perlman, G. Ghoshal, and R. Sinatra, published in Scientific Reports

      Here we explore systematically the topological limitations of urban bicycle network development. For 62 cities we study different variations of growing a synthetic bicycle network between an arbitrary set of points routed on the urban street network. We find initially decreasing returns on investment until a critical threshold, posing fundamental consequences to sustainable urban planning: Cities must invest into bicycle networks with the right growth strategy, and persistently, to surpass a critical mass. Growing networks from scratch makes our approach a generally applicable starting point for sustainable urban bicycle network planning with minimal data requirements.
      The paper comes with an accompanying data visualization: https://growbike.net

    2. Identifying urban features for vulnerable road user safety in Europe, by M. Klanjcic, L. Gauvin, M. Tizzoni, and M. Szell, published in EPJ Data Science

      We identify urban features that are determinants of vulnerable road user safety through the analysis of inter-mode collision data across 24 European cities. We observe that cities with the highest rates of walking and cycling modal shares are the safest for the most vulnerable users. Our results suggest that policies aimed at increasing the modal share of walking and cycling are key to improve road safety for all road users.
      We explain and motivate our project in this accompanying blogpost (to appear on https://blogs.biomedcentral.com): 

      Identifying urban features for vulnerable road user safety in Europe

      Which traffic participants and which urban features are most associated with road deaths? Recently published work in EPJ Data Science explores this question with data from 24 European cities.

      Road crashes result in yearly 1.3 million deaths and 2.3 trillion USD of economic damage. Because of this pressing societal issue, the UN has declared in 2015 the global sustainability goal to halve the number of road deaths by 2020. This goal failed: Road deaths keep rising worldwide.

      Many cities are wondering how to solve this issue. However, they might not have the full picture because road crash statistics tend to be reported in a victim-centered way: There are detailed statistics on the distributions of victim demographics such as age or gender, but this neglects necessary information for answering two important questions towards better crash prevention: 1) Who causes the crashes? 2) Why do crashes happen?

      The first question can be explored via the so-called casualty matrix. It shows the casualties between all combinations of different traffic participants, for example the threat of cars on cars, of cars on pedestrians, or the threat of trucks on cyclists.

      As has been previously shown in an impressive data visualization by a Dutch journalist and researcher team, the by far biggest threat to human life on urban streets in the Netherlands is motorized vehicles – cars and trucks – while cyclists and pedestrians are overwhelmingly their victims and harmless. This sounds plausible, but a systematic, quantitative study over multiple countries has been missing.

      The second question – Why do crashes happen? – is much harder to answer. Generally crashes happen in an interplay between the individual behaviors of crash participants and their environments.

      Environmental features like the extent of pedestrian areas, cycling tracks, or speed limits, are easier to collect than behavioral data, therefore their relation to road user risk could be explored in a straightforward way. And because the environment can be changed or regulated by decision makers, they can be held responsible to act.

      To support with evidence such actions towards making cities safer, the OECD recently called for developing a modern approach to road safety: 1) collect and analyze crash data from a larger set of cities, 2) investigate the relationships between urban shape, density, speeds, and road user risk, and 3) analyze casualty matrices.

      Inspired by these OECD recommendations and the Dutch data visualization, in our work we collected crash data from 24 cities in 5 European countries with high enough resolution to build and explore casualty matrices, to quantify road safety in a systemic approach, and to identify those urban features that are most relevant, especially for vulnerable road users like pedestrians who are known to be disproportionally impacted.

      Exploring the casualty matrices first, we found the same overall picture as our Dutch colleagues, see Fig. 1: Cars are the most substantial hazard. However, we also found considerable local variations. For example, cars are a considerable threat to pedestrians and cyclists in inner London, but this is much less the case in Barcelona.

      Figure 1: Casualty matrices for 2018 show road deaths and serious injuries after a traffic participant on the left collided with one on the bottom. Cars are responsible for the majority of road deaths/injuries, while columns for pedestrians and cyclists do not appear because they pose practically no risk to others.

      When normalizing the number of deaths and serious injuries by population, we found British cities to be most dangerous, while Oslo is by far the least dangerous. This is not surprising given how much Oslo has recently invested into following a Vision Zero strategy, i.e. to aim for zero road fatalities, which they achieved in 2019.

      Finally, we set out to answer: What are the urban features most associated with crashes? Here we considered several features acquired from different sources, like OpenStreetMap: population density, the amount of bicycle tracks versus car lanes, the fraction of low-speed-limit streets, the distribution of how people move (walking, cycling, public transport, or motor vehicles), temperature, precipitation, and GDP.

      Using an information theory measure to identify the most fitting pairings of these features with road crashes, we found the best significant predictor, see Fig. 2: Cities with more people walking have less road deaths.

      Figure 2: The share of people walking in a city is a significant predictor for less casualties, for any traffic participant killed or seriously injured by a car. Numbers are regression coefficients, black borders denote statistical significance at p < 0.05.

      Interestingly, this result extends to all modes of transport: More walking is associated not just with higher pedestrian safety, but also with higher cyclist and motorist safety.

      Apart from the share of walking, a similarly strong association with road safety is having more streets limited to at most 30 km/h.

      We need to be clear that our results can be only as good as the underlying data, and these can have large reporting biases. For example, crashes with cyclists are often not reported, and different EU countries have different reporting procedures. So, more research and more standardized policies on crash reporting are needed. Also, we only calculated statistical correlations, so we cannot say anything about cause and effect.

      Nevertheless, our data-driven conclusions support a modern, evidence-based paradigm of road safety, suggesting this advice to urban decision makers: Make your cities more walkable and remove the hazard of cars. Besides the massive public health benefits, this will make your city more livable and its transport system more sustainable.

Three years of NERDS

NERDS was founded exactly 3 years ago by three young assistant professors and one associate professor, to be a reference point at ITU for the research on network and data science applications to social systems. At 3 years old, we have learned to say our name when asked, to not touch hot objects, and to ask “Why?”. We have also grown to a staggering 14 members and have become a vibrant research group with seminars, visiting interns, and fun social gatherings.

On our journey we have made many local friends and strengthened our ties, from DTU and KU (SODAS) to organizations like Supercykelstier. We have also impressed several funding agencies on the way, including VILLUM Foundation, Carlsberg Foundation, DIREC, or the Danish Ministry of Transport – so much that they entrusted us with enough funding to grow our research group further. BTW: We have an open call for 3 Phds/Postdocs.

More of our most important achievements so far:

  • Publications: We have published 46 papers, some of them in top venues like Nature or PNAS, on as diverse topics as bicycle network growth, gender inequality, or multilayer networks.
  • Organization: Together with KU ad DTU we brought DataBeers to Copenhagen and held two successful (booked out) events so far with 150 attendants each. After a pandemic break we look forward to reboot Databeers soon! More recently, Roberta became co-lead of the networks and graphs collaboratory at the newly established AI Pioneer centre.
  • Scientific exchange: After kicking off successfully our ongoing NERDS lunch seminar series in 2019, we have now restarted the series. Let us know if you are interested to present to us!
  • Outreach: Michael’s award-winning data visualization project “What the Street!?” got incorporated into the permanent exhibition of Futurium, Berlin. With our students we also developed other platforms, such as growbike.net and fixbike.net, and we authored several public opinion pieces engaging in policy discussions. We are also maintaining an active Twitter account, connecting internationally with researchers and industry: @nerdsitu
  • Media Coverage: We were covered by top international media such as Le Monde, Der Spiegel, Fast Company, and got interviewed by Captain Kirk.

What does the near future hold?

  • We will hire more postdocs and PhD students with our newly acquired grants
  • We will soon say goodbye to our long-term members Bojan and Yanmeng
  • We will celebrate one of us becoming Full Professor this year
  • We are awaiting and continually submitting even more grant applications to expand
  • Organizing more DataBeers and social events

Looking back to our goals 3 years ago, we have all reason to be proud to have 1) built up a flourishing network of Denmark-based network/data science research groups, connecting ITU, KU, DTU, and others, 2) successfully impressed several funding agencies and public stakeholders to engage with us solving societal problems with our research. We will continue along this road, developing further our group in a safe and fun environment.

Live long and prosper 🖖
Luca, Michele, Tiago, Bojan, Ane, Luca 2, Vedran, Roberta, Sandro, Michael, Anastassia, Yanmeng