Virality Prediction and Community Structure in Social Networks
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Virality Prediction and Community Structure in Social Networks Yong-Yeol “YY” Ahn @yy Most populated countries 1,300,000,000+ 1,200,000,000+ 300,000,000+ Most populated countries 1,300,000,000+ 1,200,000,000+ 1,100,000,000+ 500,000,000+ 300,000,000+ Social media can amplify messages. “Casually pepper spraying everything cop” meme Companies are desperately trying to leverage social media to make their products and ads viral. Original, useful ideas - hard “viral marketing” ‘Astroturfing’ may change election results. “1/3 of online reviews may be fake.” - Bing Liu (UIC) How can we understand virality? Can we predict viral memes? Clue #1: Complex contagion Memes = Infectious diseases? Germs spread through the “social” network Memes, ideas and behaviors also spread through social network. Memes = Infectious diseases? Maybe not. “Large” world “Small” world D. Centola, Science 2010 Which network is better at spreading information quickly? “Large” world “Small” world D. Centola, Science 2010 Multiple exposures are crucial. Social reinforcement Complex Contagion 三人成虎 三人成虎 three 三人成虎 three people construct 三人成虎 three people construct 三人成虎 three people tiger ? ? ! Complex Contagion needs multiple exposures. & Social contagion seems to be complex contagions. Clustering should be important. (B) Social Reinforcement Multiple Exposures Multiple Exposures A High Clustering Low Clustering (D) Retweet Network (E) Follower Network Figure 1: The importance of community structure in the spreading of social contagions. (A) Structural trapping: dense communities with few outgoing links naturally trap informa- tion flow. (B) Social reinforcement: people who have adopted a meme (black nodes) trigger multiple exposures to others (red nodes). In the presence of high clustering, any additional adoption is likely to produce more multiple exposures than in the case of low clustering, in- ducing cascades of additional adoptions. (C) Homophily: people in the same community (same color nodes) are more likely to be similar and to adopt the same ideas. (D) Diffusion structure based on retweets among Twitter users sharing the hashtag #USA. Blue nodes represent English users and red nodes are Arabic users. Node size and link weight are proportional to retweet ac- tivity. (E) Community structure among Twitter users sharing the hashtags #BBC and #FoxNews. Blue nodes represent #BBC users, red nodes are #FoxNews users, and users who have used both hashtags are green. Node size is proportional to usage (tweet) activity, links represent mutual following relations. 10 Highly clustered structure? Communities! Newman, 2006 Communities should enhance the spread of complex contagion. Clue #2: Homophily “Birds of a feather flock together.” Eric Fischer, Race and ethnicity Adamic & Glance, 2005 You are likely to share similar interests with your friends. You are more likely to adopt something from your social circles. Again, communities become important. A community ~ a common characteristic or shared interests Adamic & Glance, 2005 (C) Homophily (E) Follower Network Figure 1: The importance of community structure in the spreading of social contagions. (A) Structural trapping: dense communities with few outgoing links naturally trap informa- tion flow. (B) Social reinforcement: people who have adopted a meme (black nodes) trigger multiple exposures to others (red nodes). In the presence of high clustering, any additional adoption is likely to produce more multiple exposures than in the case of low clustering, in- ducing cascades of additional adoptions. (C) Homophily: people in the same community (same color nodes) are more likely to be similar and to adopt the same ideas. (D) Diffusion structure based on retweets among Twitter users sharing the hashtag #USA. Blue nodes represent English users and red nodes are Arabic users. Node size and link weight are proportional to retweet ac- tivity. (E) Community structure among Twitter users sharing the hashtags #BBC and #FoxNews. Blue nodes represent #BBC users, red nodes are #FoxNews users, and users who have used both hashtags are green. Node size is proportional to usage (tweet) activity, links represent mutual following relations. 10 Trivial example: Language and Country (E) Follower Network English #usa BBC News #bbc Fox News #foxnews Arabic #usa FigureFigureRetweet 1: 1: The The importance importance Network of community of community structure structure in theFollower in spreading the spreading of social Network of contagions. social contagions. (A) Structural trapping: dense communities with few outgoing links naturally trap informa- (A) Structural trapping: dense communities with few outgoing links naturally trap informa- tion flow. (B) Social reinforcement: people who have adopted a meme (black nodes) trigger tion flow. (B) Social reinforcement: people who have adopted a meme (black nodes) trigger multiple exposures to others (red nodes). In the presence of high clustering, any additional multiple exposures to others (red nodes). In the presence of high clustering, any additional adoption is likely to produce more multiple exposures than in the case of low clustering, in- ducingadoption cascades is likely of additional to produce adoptions. more (C) multipleHomophily exposures: people than in the in the same case community of low clustering, (same in- colorducing nodes) cascades are more of likely additional to be similar adoptions. and to (C) adoptHomophily the same: people ideas. in(D) the Diffusion same community structure (same basedcolor on retweets nodes) are among more Twitter likely users to be sharing similar the and hashtag to adopt#USA the. Blue same nodes ideas. represent (D) Diffusion English structure usersbased and red on retweets nodes are among Arabic Twitter users. Node users size sharing and link the hashtagweight are#USA proportional. Blue nodes to retweet represent ac- English tivity.users (E) and Community red nodes structure are Arabic among users. Twitter Node users size sharing and link the weight hashtags are#BBC proportionaland #FoxNews to retweet. ac- Bluetivity. nodes (E) represent Community#BBC users, structure red among nodes are Twitter#FoxNews usersusers, sharing and the users hashtags who have#BBC usedand both#FoxNews. hashtagsBlue nodesare green. represent Node#BBC size isusers, proportional red nodes to usage are #FoxNews (tweet) activity,users, and links users represent who have mutual used both followinghashtags relations. are green. Node size is proportional to usage (tweet) activity, links represent mutual following relations. 10 10 Both clues indicate that Communities should play a crucial role in complex contagion. Communities weakly trap simple contagions. Communities strongly trap complex contagions. Communities: traps for random walkers Rosvall, Bergstrom, Lambiotte, ... (A) Structural Trapping Exposures (D) Retweet Network Affects both simple and complex contagions. Figure 1: The importance of community structure in the spreading of social contagions. (A) Structural trapping: dense communities with few outgoing links naturally trap informa- tion flow. (B) Social reinforcement: people who have adopted a meme (black nodes) trigger multiple exposures to others (red nodes). In the presence of high clustering, any additional adoption is likely to produce more multiple exposures than in the case of low clustering, in- ducing cascades of additional adoptions. (C) Homophily: people in the same community (same color nodes) are more likely to be similar and to adopt the same ideas. (D) Diffusion structure based on retweets among Twitter users sharing the hashtag #USA. Blue nodes represent English users and red nodes are Arabic users. Node size and link weight are proportional to retweet ac- tivity. (E) Community structure among Twitter users sharing the hashtags #BBC and #FoxNews. Blue nodes represent #BBC users, red nodes are #FoxNews users, and users who have used both hashtags are green. Node size is proportional to usage (tweet) activity, links represent mutual following relations. 10 (B) Social Reinforcement Multiple Exposures Multiple Exposures A High Clustering Low Clustering (D) Retweet Network (E) Follower Network Affects complex contagions. Figure 1: The importance of community structure in the spreading of social contagions. (A) Structural trapping: dense communities with few outgoing links naturally trap informa- tion flow. (B) Social reinforcement: people who have adopted a meme (black nodes) trigger multiple exposures to others (red nodes). In the presence of high clustering, any additional adoption is likely to produce more multiple exposures than in the case of low clustering, in- ducing cascades of additional adoptions. (C) Homophily: people in the same community (same color nodes) are more likely to be similar and to adopt the same ideas. (D) Diffusion structure based on retweets among Twitter users sharing the hashtag #USA. Blue nodes represent English users and red nodes are Arabic users. Node size and link weight are proportional to retweet ac- tivity. (E) Community structure among Twitter users sharing the hashtags #BBC and #FoxNews. Blue nodes represent #BBC users, red nodes are #FoxNews users, and users who have used both hashtags are green. Node size is proportional to usage (tweet) activity, links represent mutual following relations. 10 (C) Homophily (E) Follower Network Affects complex contagions. Figure 1: The importance of community structure in the spreading of social contagions. (A) Structural trapping: dense communities with few outgoing links naturally trap