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- 1. Network Analysis Basics and applications to online data<br />Katherine Ognyanova<br />University of Southern California<br />Prepared for the Annenberg Program <br />for Online Communities, 2010.<br />
- 2. Relational data <br />Node (actor, vertex, etc.) <br />Tie ( link, relation, edge, etc.) <br />
- 3. Internet<br />Internet Backbone: Each line is drawn between two nodes, representing two IP addresses. Source: Wikipedia<br />
- 4. Global Media Networks<br />Media corporations network. Source: Arsenault & Castells, 2008<br />
- 5. US Senate<br />US Senate cosponsorship network 1973-2004. Source: Fowler, 2006<br />
- 6. High-School Romance<br />Source: Easley, Kleinberg (2010) Networks, Crowds and Markets<br />
- 7. Online Social Networks<br />Twitter, 2010<br />
- 8. SNiF<br />Source: noah.cx, 2010<br />
- 9. Basic Types of Networks<br /> HP<br /> MS<br /> Jill<br />John<br />Paul<br /> Jill<br />Paul<br />John<br />Kate<br />Kate<br />Jim<br />Jim<br /> Tom<br /> Jill<br /> Tom<br /> Jill<br />
- 10. A closer look at links<br />John<br /> Bob<br />John<br /> Bob<br />John<br /> Bob<br />John<br /> Bob<br />+<br />5<br />colleague<br />friend<br />
- 11. Distance in Networks<br /> B<br /> B<br /> B<br /> B<br /> A<br /> C<br /> E<br /> F<br /> A<br /> C<br /> E<br /> F<br /> A<br /> C<br /> E<br /> F<br /> A<br /> C<br /> E<br /> F<br /> D<br /> D<br /> D<br /> D<br />
- 12. A Closer Look at Nodes<br />
- 13. Node Types<br /> Isolate<br /> Liaison<br /> Gatekeeper<br /> Star<br /> Bridge<br />
- 14. Node Centrality<br />
- 15. Network Centralization & Density<br />Degree, closeness and betweenness are centrality measures for individual nodes.<br />Centralization is a network-level measure. It measures the degree to which an entire network is focused around a few central nodes. In a decentralized network, the links are more or less evenly distributed among nodes.<br />Centralization is calculated based on the differences in degree centrality between nodes divided by the maximum possible sum of differences.<br />Density : Ratio of the number of links to the number of possible links in the network<br />Size: The number of nodes in a network<br />
- 16. Example: Terrorist Networks<br />Source: Business 2.0 December 2001. Six Degrees of Mohamed Atta<br />
- 17. Social Network Measures & Mechanisms <br />
- 18. US Political Blogosphere<br />Linking patterns in the US political blogosphere. Source: Adamic & Glance (2005)<br />
- 19. What does network data look like?<br />Although there are other options (edge lists, node lists, etc.) network data is typically used in the form of a matrix .<br />Row X column Y is 1 if there is a link from X to Y - and 0 if there is no link.<br />The diagonal represents self-loops: links from X back to X. <br />C<br />D<br />A<br />B<br />
- 20. Using UCINET for Network Analysis<br />1<br />2<br /><ul><li>UCINET: download from this website. You get two months of free trial.
- 21. Data Input: - Direct: Click on (1) – copy and paste from Excel or enter manually a matrix. - Import: Data menu -> Import via Spreadsheet - > Full matrix w/ multiple sheets. For every network Ucinet will create two files: .##h and .##d. If you move them, move both.
- 22. Density : Network menu -> Cohesion -> Density
- 23. Reciprocity / Transitivity / Clustering : Network menu -> Cohesion -> Reciprocity / Transitivity / Clustering
- 24. Node centrality : Network -> Centrality -> Multiple measures (old)
- 25. Visualization: Press button (2) for NetDraw. </li></li></ul><li>Studying Social Structures Through Network Analysis<br />
- 26. Collecting Network Data<br />
- 27. Example: Snowball Sampling<br />Source: Valente (2010) Social Networks and Health<br />
- 28. The Web as a Network<br />
- 29. E-Mail and Discussion Forum Networks<br />Source: Welser, Gleave, Fisher & Smith, 2007<br />
- 30. Diffusion Through Online Social Networks<br />
- 31. Online Resources for Social Networks<br />How can we collect data about online networks?<br /><ul><li> Facebook:Name Gen Web by Bernie Hogan is a Facebook app that will collect data about your network and let you download it in a UCINET file format.
- 32. NodeXLis an add-on for network analysis in Excel. It can collect and analyze Twitter, Flickr and e-mail nets.
- 33. SNAP (Stanford Network Analysis Platform) has a data library with big network datasets from Google, Amazon, Wikipedia, social network sites, etc.
- 34. IssueCrawler, LexiURLand SocSciBotare some of the available solutions for crawling web pages and collecting hyperlink networks.</li>

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