About

Welcome!

I am a data scientist with several years of experience at world-leading organisations (Oxford, Cambridge, Southampton Universities; dunnhumby, Morgan Stanley, UK Department of Health in London). I am specialised in data science and machine learning for prediction, causal inference, and ranking. My work has been honoured with awards and has been featured in top media outlets.

I hold a PhD in Computer Science from the University of Southampton (2018), an MSc in Operational Research from the University of Southampton (2014, Distinction, dissertation prize, full scholarship), and a BA (Hons) in Computer Science from the University of Cambridge (St John's College 2012, 2.1, dissertation high commendation).

Since February 2020, I have been working as a Research Data Scientist at dunnhumby, London. I am also a research associate of the Unviersity of Oxford, Oxford Internet Institute.

I am also on Twitter, LinkedIn, and Google Scholar.

Research

Research Interests

My postdoctoral research at Oxford has focused on measuring and predicting the impact and reach of online misinformation using large social media datasets. My PhD research was on causal inference for estimating the social influence of online communications on real-world outcomes, at the individual and at the collective level. My academic research interests relate to the areas of online social influence, causal inference, social network analysis, computational social science, and data science.

Publications

• Liotsiou, D., Ganesh, B., and Howard, P. N. (2020) 'Predicting Engagement with the Internet Research Agency's Facebook and Instagram Campaigns around the 2016 U.S. Presidential Election.' arXiv preprint [arXiv:2010.14950]
• Savolainen L., Trilling. D., and Liotsiou, D. (2020) 'Delighting and Detesting Engagement: Emotional Politics of Junk News.', Social Media + Society, 6(4). doi: 10.1177/2056305120972037 [Sagepub link]
• Liotsiou, D., Kollanyi, B., and Howard, P. N. (2019) 'The Junk News Aggregator: Examining junk news posted on Facebook, starting with the 2018 US Midterm Elections.'' arXiv preprint [arXiv:1901.07920] - Selected honours: ​ Featured on the European Comission/ European Research Council (ERC) website . - Selected news coverage: ​ TechCrunch​, ​ Newsweek​, BuzzFeed News, The Bulletin of the Atomic Scientists (video interview).
• Howard, P. N., Ganesh, B., Liotsiou, D., Kelly, J., & François, C. (2018) 'The IRA, Social Media and Political Polarization in the United States, 2012-2018.' Working Paper 2018.2. Oxford, UK. 46 pp. [link] (Author order: Oxford P.I., then Oxford postdocs alphabetically, then collaborators from Graphika). - Policy impact: This paper was cited by the US Senate, EU policymakers, and the UK Parliament, e.g. in the UK House of Commons Digital, Culture, Media and Sport (DCMS) Committee in their Final Report on Disinformation and 'fake news' (2019) .
  - Selected news coverage: MSNBC interview, The Washington Post (cover story above the fold and further articles), The New York Times (cover story above the fold and further articles), PBS News Hour, ABC News, BBC, The Guardian, The Independent, Ars Technica (with interview quotes), Yahoo Finance (with interview quotes) [more details]
• Liotsiou, D., Moreau, L., and Halford, S. (2016) 'Social Influence: From Contagion to a Richer Causal Understanding.'' In International Conference on Social Informatics (pp. 116-132). Springer International Publishing. [paper on SpringerLink, author copy; poster] Best Poster Award for poster accompanying 17-page full-length paper in proceedings, plus short talk.

Peer-reviewed conference presentations

• Liotsiou, D. and Howard, P. N. (2019) "Measuring the Influence of Online Misinformation: A Hierarchy of Social Media Data." The 5th Annual International Conference on Computational Social Science (IC2S2). [paper, poster]
• Liotsiou, D., Moreau, L., and Halford, S. (2017) "Social Influence: from Contagion to a Richer Causal Understanding." The 5th annual UK Causal Inference Meeting, University of Essex, United Kingdom.
• Liotsiou, D., Moreau, L., and Halford, S. (2017) "Social Influence: from Contagion to a Richer Causal Understanding."Data Natives Meeting, City University of London, UK. (2017) "Social Influence: From contagion to a richer causal understanding." 2017.

Theses

• Liotsiou D. (2018, October). Measuring the Social Influence of Online Communications at the Individual and Collective Level: A Causal Framework. PhD Thesis. [abstract]
• Liotsiou D. (2014, September). Projecting Dental Care Need in England over the Next 20-30 Years. Masters Thesis. Sponsor Award.
• Liotsiou D. (2012, June). Parallelising Ant Colony Optimisation-based Solutions to the Vehicle Routing Problem in Scala. Undergraduate Thesis. High Commendation.

Service

PC Member for ACM Conference on Hypertext and Social Media (2019); reviewer for EPJ Data Science (2018), ICA Computational Communication Research (2021).

Other Outreach Activities and Links

• Research talk at the annual Oxbrdige Women in Computer Science conference (2019).
• Oxford University podcast on junk news and AI (2018).
• Profile on the Oxford University AI Research directory, including a discussion of the challenge of causal reasoning in AI (2018).
• Testimonial with advice for prospective Computer Science undergraduate students of St John's College at the University of Cambridge (2013).




Teaching

During my PhD, I demonstrated and/or marked for the following courses and short seminars:

Courses

• Java programming labs, undergraduate-level (demonstator)
• Funtional programming in Scheme, undergraduate-level (marker)
• Social network analysis, postgraduate-level (group project mentor)
• Software engineering, undergraduate-level (group project mentor)

Seminars

• Introduction to Data Science in Python, for secondary-education teachers
• Introduction to Machine Learning in Python, for PhD students





Resources

Causality

Some good starting points for causal inference can be found below. This is by no means intended to be an exhaustive list, and the resources are in no particular order. I imagine I will be updating it from time to time. Some good resources for getting started on causality, which use Judea Pearl's do-calculus approach to causality:

• Judea Pearl's 1999 IJCAI Award lecture on causality. On his website he has some more recent slides and tutorials too, but this is one of the two resources he recommends starting with.
• Judea Pearl's overview paper on causality. It is very well written and fun to read. This paper is like a short version of his "Causality" book (see below).
• Judea Pearl's Primer book on Causal Inference in Statistics (co-written with Madelyn Glymour and Nicholas P. Jewell). This is a very accessible introduction to causality and how to practically apply causal methods to data.
• Judea Pearl's book on Causality, which is much longer and more technical than the Primer, and very well written.
• Cosma Shalizi at Carnegie Mellon covers causality really well in his notes/book-in-progress "Advanced Data Analysis from an Elementary Point of View", chapters 20, and 24-28.

Beyond those, some other good resources (some using the potential outcomes framework rather than/in addition to Pearl's do-notation) are:

• The Morgan-Winship book "Counterfactuals and Causal Inference", 2nd edition. Particularly: chapter 1.1, parts II (especially 2.1-2.5), III (especially 3.1)
• Blog posts:
  • Adam Kelleher's series of posts on Causal Data Science on Medium, which offers a very accessible introduction to causality.
  • Pearl's causality blog.
  • The "Statistical Modeling, Causal Inference, and Social Science" blog.
• Materials from University courses:
  • David Blei at Columbia has started a course on causality, his reading list includes many of the above sources, among others.
  • Thomas Richardson at the University of Washington also teaches a course with this reading list.