The Rules of Contagion

noting that despite their widespread use, the concept of randomised experiments (often called ‘A/B tests’) seems to make many people uncomfortable – even if the individual options are innocuous and the study is ethically designed. One 2019 study found that ‘people frequently rate A/B tests designed to establish the comparative effectiveness of two policies or treatments as inappropriate even when universally implementing either A or B, untested, is seen as appropriate’. Source: Meyer M.N. et al., ‘Objecting to experiments that compare two unobjectionable policies or treatments’, PNAS, 2019.

35. Berger J. and Milkman K.L., ‘What Makes online Content Viral?’, Journal of Marketing Research, 2011.

36. Heath C. et al., ‘Emotional selection in memes: the case of urban legends’, Journal of Personality and Social Psychology, 2001.

37. Tufekci Z., ‘YouTube, the Great Radicalizer’, New York Times, 10 March 2018.

38. Baquero F. et al., ‘Ecology and evolution of antibiotic resistance’, Environmental Microbiology Reports, 2009.

39. Background from: De Domenico M. et al., ‘The Anatomy of a Scientific Rumor’, Scientific Reports, 2013.

40. Goel S. et al., ‘The Structural Virality of Online Diffusion’, Management Science, 2016.

41. Goel S. et al., ‘The Structure of Online Diffusion Networks’, EC’12 Proceedings of the 13th ACM Conference on Electronic Commerce, 2012; Tatar A. et al., ‘A survey on predicting the popularity of web content’, Journal of Internet Services and Applications, 2014.

42. Watts D.J. et al., ‘Viral Marketing for the Real World’, Harvard Business Review, 2007.

43. Method from: Blumberg S. and Lloyd-Smith J.O., PLOS Computational Biology, 2013. This calculation works even if there is potential for superspreading events.

44. Chowell G. et al., ‘Transmission potential of influenza A/H7N9, February to May 2013, China’, BMC Medicine, 2013.

45. Watts D.J. et al., ‘Viral Marketing for the Real World’, Harvard Business Review, 2007. Note that technical issues with the e-mail campaign may have artificially reduced the reproduction number for Tide to some extent.

46. Breban R. et al., ‘Interhuman transmissibility of Middle East respiratory syndrome coronavirus: estimation of pandemic risk’, The Lancet, 2013.

47. Geoghegan J.L. et al., ‘Virological factors that increase the transmissibility of emerging human viruses’, PNAS, 2016.

48. García-Sastre A., ‘Influenza Virus Receptor Specificity’, American Journal of Pathology, 2010.

49. Adamic L.A. et al., ‘Information Evolution in Social Networks’, Proceedings of the Ninth ACM International Conference on Web Search and Data Mining (WSDM’16), 2016.

50. Cheng J. et al., ‘Do Diffusion Protocols Govern Cascade Growth?’, AAAI Publications, 2018.

51. Background on early BuzzFeed transmission: Rice A., ‘Does BuzzFeed Know the Secret?’, New York Magazine, 7 April 2013.

52. Watts D.J. et al., ‘Viral Marketing for the Real World’, Harvard Business Review, 2007. For ease of reading, the shorthand ‘<’ has been replaced by ‘less than’ in the text.

53. Guardian Datablog, ‘Who are the most social publishers on the web?’, The Guardian Online, 3 October 2013.

54. Salmon F., ‘BuzzFeed’s Jonah Peretti Goes Long’, Fusion, 11 June 2014.

55. Martin T. et al., ‘Exploring Limits to Prediction in Complex Social Systems’, Proceedings of the 25th International Conference on World Wide Web, 2016.

56. Shulman B. et al., ‘Predictability of Popularity: Gaps between Prediction and Understanding’, International Conference on Web and Social Media, 2016.

57. Cheng J. et al., ‘Can cascades be predicted?’, Proceedings of the 23rd International Conference on World Wide Web, 2014.

58. Yucesoy B. et al., ‘Success in books: a big data approach to bestsellers’, EPJ Data Science, 2018.

59. McMahon V., ‘#Neknominate girl’s shame: I’m sorry for drinking a goldfish’, Irish Mirror, 5 February 2014.

60. Many Neknomination videos can be seen on YouTube; Fricker M., ‘RSPCA hunt yob who downed NekNomination cocktail containing cider, eggs, battery fluid, urine and THREE goldfish’, Mirror, 5 February 2014.

61. Example coverage: Fishwick C., ‘NekNominate: should Facebook ban the controversial drinking game?’, The Guardian, 11 February 2014; ‘“Neknomination”: Facebook ignores calls for ban after two deaths’, Evening Standard, 3 February 2014.

62. More or Less: ‘Neknomination Outbreak’, BBC World Service Online, 22 February 2014.

63. Kucharski A.J., ‘Modelling the transmission dynamics of online social contagion’, arXiv, 2016.

64. Researchers at the University of Warwick found a similar level of predictability. Based on the dynamics of neknomination, they correctly forecast the four-week duration of the ice bucket challenge shortly after it emerged a few months later. Sprague D.A. and House T., ‘Evidence for complex contagion models of social contagion from observational data’, PLOS ONE, 2017.

65. Cheng J. et al., ‘Do Cascades Recur?’, Proceedings of the 25th International Conference on World Wide Web, 2016.

66. Crane R. and Sornette D., ‘Robust dynamic classes revealed by measuring the response function of a social system’, PNAS, 2008.

67. Tan C. et al., ‘Lost in Propagation? Unfolding News Cycles from the Source’, Association for the Advancement of Artificial Intelligence, 2016; Tatar A. et al., ‘A survey on predicting the popularity of web content’, Journal of Internet Services and Applications, 2014.

68. Vosoughi S. et al., ‘The spread of true and false news online’, Science, 2018.

69. Examples from: Romero D.M., ‘Differences in the Mechanics of Information Diffusion Across Topics: Idioms, Political Hashtags, and Complex Contagion on Twitter’, Proceedings of the 20th International Conference on World Wide Web, 2011; State B. and Adamic L.A., ‘The Diffusion of Support in an Online Social Movement: Evidence from the Adoption of Equal-Sign Profile Pictures’, Proceedings of the 18th ACM Conference on Computer Supported Cooperative Work & Social Computing, 2015; Guilbeault D. et al., ‘Complex Contagions: A Decade in Review’, in Lehmann S. and Ahn Y. (eds.), Spreading Dynamics in Social Systems (Springer Nature, 2018).

70. Weng L. et al., ‘Virality Prediction and Community Structure in Social Networks’, Scientific Reports, 2013.

71. Centola D., How Behavior Spreads: The Science of Complex Contagions (Princeton University Press, 2018).

72. Anderson C., ‘The End of Theory: The Data Deluge Makes the Scientific Method Obsolete’, Wired, 23 June 2008.

73. ‘Big Data, for better or worse: 90 per cent of world’s data generated over last two years’, Science Daily, 22 May 2013.

74. Widely attributed to Goodhart in this form. Original statement: ‘Any observed statistical regularity will tend to collapse once pressure is placed upon it for control purposes’. Goodhart C., ‘Problems of Monetary Management: The U.K. Experience’, in Courakis, A. S. (ed.), Inflation, Depression, and