Delft University of Technology Countering Rumours in Online Social Media Ebrahimi Fard, A. DOI 10.4233/uuid:bf835c87-da7b-4dd7-bfad-41fd1bb537c0 Publication date 2021 Document Version Final published version Citation (APA) Ebrahimi Fard, A. (2021). Countering Rumours in Online Social Media. https://doi.org/10.4233/uuid:bf835c87-da7b-4dd7-bfad-41fd1bb537c0 Important note To cite this publication, please use the final published version (if applicable). Please check the document version above. Copyright Other than for strictly personal use, it is not permitted to download, forward or distribute the text or part of it, without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license such as Creative Commons. Takedown policy Please contact us and provide details if you believe this document breaches copyrights. We will remove access to the work immediately and investigate your claim. This work is downloaded from Delft University of Technology. For technical reasons the number of authors shown on this cover page is limited to a maximum of 10. COUNTERING RUMOURSIN ONLINE SOCIAL MEDIA COUNTERING RUMOURSIN ONLINE SOCIAL MEDIA Dissertation for the purpose of obtaining the degree of doctor at Delft University of Technology by the authority of the Rector Magnificus, Prof. dr. ir. T. H. J. J. van der Hagen, chair of the Board for Doctorates to be defended publicly on Tuesday 9 March 2021 at 15:00 o’clock by Amir EBRAHIMI FARD Master of Science in Management and Economics, Sharif University of Technology, Iran born in Qom, Iran. This dissertation has been approved by the promotors. Composition of the doctoral committee: Rector Magnificus, Chairperson Prof. dr. B.A. van de Walle Delft University of Technology and UNU-MERIT, promotor Prof. dr. D. Helbing Delft University of Technology and ETH Zurich, promotor Dr. ir. T. Verma Delft University of Technology, copromotor Independent members: Prof. dr. M.J. van den Hoven Delft University of Technology Prof. dr. ir. A. Bozzon Delft University of Technology Prof. dr. H. Alani The Open University Dr. ir. I. Lefter Delft University of Technology Keywords: Rumours, social media, recommender systems, counter-strategies, one-class classification, social manipulation. Printed by: Gilderprint Cover design: Amir Ebrahimi Fard (Based on a design first published in the "Die Karikatur und Satire in der Medizin: Medico-Kunsthistorische Studie von Professor Dr. Eugen Holländer, 2nd edn (Stuttgart:Ferdinand Enke, 1921), fig. 79 (p. 171)." (The original design is in the public do- main)) © Copyright Amir Ebrahimi Fard, 2021. All rights reserved. ISBN 978-94-6419-147-9 An electronic version of this dissertation is available at http://repository.tudelft.nl/. The research in this dissertation was funded by Delft University of Technology. To Maman o Baba ACKNOWLEDGEMENTS This book has come to an end (but) the story yet remains Sa’di Although my name is written as the author of this manuscript, my PhD was a #col- lective_effort, and a stellar group of people tremendously supported me. My deepest gratitude goes to @Maman, @Baba, and @Reza, three gems in my life. Thank you for your eternal encouragement and endless support in everything I do. You always pushed me to become the best version of myself, remain #hopeful, and face chal- lenges. I learned #patience, #perseverance, and #dedication from you. Thank you for always being there for me . To @Bartel, @Dirk, @Trivik, and @Scott, I was privileged to do my PhD under your su- pervision. You lit up my research path and helped me to #grow in academia and become an #independent_researcher. You gave me the #freedom to #explore from Coase theo- rem and industrial districts to rumour spreading. You always encouraged me to choose a research topic that I am really attached to. I would not stand where I am now without your support. My sincere and heartfelt gratitude and appreciation to you for providing me with the guidance and counsel I needed to succeed in my PhD . @Bartel, you were not only my promotor, you were also my #role_model and the source of #inspira- tion during my PhD journey, I will miss being your student. @Dirk, every time you came up with an idea, you blew my mind. I wish my PhD days had more than 24 hours to spend on those #brilliant_ideas. @Trivik, I cannot emphasise how much I learned from you; whether about #technical or #soft_subjects. I am very grateful for all this support. @Scott, you helped me to start my PhD and formulate my research. You also provided me with several great #collaboration_opportunities. Thank you so much for all of them. How could I possibly finish my PhD without my #fantastic_friends @Natasa, @João, @Annebeth, @Majid, @Javanshir, @Vivian, @Farzam, @Sharlene, @Shantanu, @Arthur, @Vittorio, @Ioanna, I was extremely fortunate that my path crossed yours. @Natasa and @Annebeth, you are the yardstick of #friendship. I am so glad that we shared an office, a neighbourhood, and a PhD graduation team . @Majid, I am very lucky to be a friend of a bright yet humble person like you. I truly appreciate all your support during my PhD journey. Perhaps if I want to continue this acknowledgement letter, it will not end anytime soon, as many people kindly supported me in this journey. By all means, thank you . Amir Ebrahimi Fard Delft, March 2021 vii CONTENTS Acknowledgements vii List of Tables xiii List of Figures xv Summary xix Samenvatting xxi 1 Introduction1 1.1 An Overview on the Phenomenon of Rumour Spreading..........2 1.2 Research Objective and Research Questions................3 1.3 Contributions and Guide to Readers....................6 1.4 Engineering Social Technologies for a Responsible Digital Future......8 2 Conceptualisation of False and Unverified Information 11 2.1 Introduction................................ 12 2.2 The variations of false and unverified information............. 12 2.2.1 Rumour............................... 12 2.2.2 Gossip................................ 13 2.2.3 Legend................................ 14 2.2.4 Propaganda............................. 14 2.2.5 Conspiracy Theory.......................... 15 2.2.6 Fake-news.............................. 15 2.2.7 Pseudoscience............................ 16 2.2.8 Misinformation........................... 17 2.2.9 The Comparison of False and Unverified Information........ 17 2.3 Process-based Perspective......................... 17 2.4 What has to be curbed?........................... 19 2.5 Conclusion................................. 20 3 The Landscape of Rumour Spreading 21 3.1 Introduction................................ 22 3.2 Communication and Rumour Spreading.................. 22 3.3 The Role of Communication technologies in rumour spreading...... 24 3.4 Recommendation systems under Scrutiny................. 26 3.4.1 Methodology and Data Collection.................. 26 3.4.2 Analysis............................... 29 3.5 Conclusion................................. 38 ix x CONTENTS 4 Countering rumours 39 4.1 Introduction................................ 40 4.2 Counter Rumour Strategies......................... 40 4.2.1 Senders Strategies.......................... 42 4.2.2 Channel Strategies.......................... 42 4.2.3 Receivers Strategies......................... 45 4.3 Evaluation of Strategies........................... 48 4.3.1 Evaluation framework........................ 48 4.3.2 Strategies effectiveness........................ 49 4.4 Conclusion................................. 50 5 An Assessment of Academic Efforts regarding Rumour Confrontation 53 5.1 Introduction................................ 54 5.2 Scientific emergence............................ 54 5.3 Method................................... 55 5.3.1 Data collection............................ 56 5.3.2 Emergence operationalization.................... 60 5.4 Results................................... 60 5.4.1 Novelty................................ 60 5.4.2 Growth................................ 65 5.4.3 Coherence.............................. 69 5.4.4 Impact................................ 77 5.5 Discussion................................. 81 5.6 Conclusion................................. 83 6 Computational Rumour Detection using One-Class Classification 85 6.1 Introduction................................ 86 6.2 Computational Rumour detection..................... 88 6.3 Data..................................... 90 6.3.1 Building the datasets......................... 90 6.3.2 Available datasets.......................... 93 6.4 Feature Extraction............................. 95 6.4.1 Linguistic & content features..................... 98 6.4.2 User features............................. 101 6.4.3 Meta-message features........................ 102 6.5 Classification................................ 102 6.5.1 Problem Statement......................... 102 6.5.2 One-class Classification Approach.................. 106 6.5.3 Experiments............................. 110 6.6 Conclusion................................. 120 7 Modelling Rumour Campaigns: A Proactive Approach 123 7.1 Introduction................................ 124 7.2 Research Background............................ 125 7.2.1 Deliberate Rumour Spreading as a Means of Information Operation. 125 7.2.2 Misinformation Machine...................... 126 7.2.3 Cyber Operations Model....................... 127 CONTENTS xi 7.3 Model development............................. 127 7.3.1 The Block Diagram.......................... 130 7.3.2 The Operationalisation of the Model................. 130 7.3.3 The Data Model..........................