In this study, user interaction in virtual communities are investigated using social network analysis in order to realize which conditions of community would result in large amount of people affected to have high purchase intention. We would also like to examine whether influences of opinion leaders are greater than the condition of network structure formed by on-line users. Besides, Brand awareness and price are also taken into account to see if they would moderate the relations between social network index and purchase intention. The conclusion is that influences of opinion leaders are not greater than number of cliques and degree of clique overlap in virtual communities. Nevertheless, opinion leader is important regarding to a brand which has lower brand awareness.

Anita, L. B., & Markus, M. L. (2004). The experienced "sense" of a virtual community: characteristics and processes. SIGMIS Database, 35(1), 64-79.
Armstrong, A., & Hagel, J. (1996). The real value of online communities. Harvard Business Review, 74 (3), 134-41.
Bakardjieva, M. (2003). Virtual Togetherness: an Everyday-life Perspective. Media, Culture & Society, 25(3), 291-312.
Bandura, A. (1986). Social foundations of thought and action. Englewood Cliffs, NJ: Prentice-Hall.
Barnes, J. A. (1972). Social Networks. New York: Addison-Wesley.
Bavelas, A. (1950). Communication patterns in task-oriented groups. Journal of the Acoustical Society of America, 22(6), 723-730.
Berner, E. S., Baker, S., Funkhouser, E. et al. (2003). Do local opinion leaders augment hospital quality improvement efforts? A randomized trial to promote adherence to unstable angina guidelines. Med Care,41,420-431.
Bikhchandani, S., Hirshleifer, D., & Welch, I. (1992). A Theory of Fads, Fashion, Custom, and Cultural Change as Informational Cascades. Journal of Political Economy, 100, 992-1026.
Blanchard, A. L., & Markus, M. L. (2002). Sense of virtual community - maintaining the experience of belonging. Paper presented at the System Sciences, 2002. HICSS. Proceedings of the 35th Annual Hawaii International Conference on.
Blau, P. M. (1977). Inequality and Heterogeneity. New York: Macmillan.
Borgatti, S. P. (1998). What Is Social Network Analysis?
Website:http://www.analytictech.com/networks/whatis.htm
Burson-Marsteller. (2001). The E-Fluentials. New York Burson-Marsteller.
Burt, R. S. (1999). The Social Capital of Opinion Leaders. The Annals of the
American Academy of Political and Social Science, 566, 37-54.
Chatman, E. (1987). Opinion leadership, poverty, and information sharing. RQ, 26(3), 341–353.
Coleman, J. S., Katz, K., & Menzel H. (1957). The Diffusion of an Innovation among Physicians. Sociometry, 20, 253-70.
Coulter, R. A., Feick, L. F., & Price, L. L. (2002). Changing Faces: Cosmetics Opinion Leadership among Women in the New Hungary. European Journal of Marketing, 36, 1287-308.
Crosby, L. A., Evans, K. R., & Cowle, D. (1990). Relationship Quality in Services Selling: An Interpersonal Influence Perspective. Management Science, 49(1), 21-38.
Dennis F. Galletta, Manju K. Ahuja, Kathleen M. Carley. (2003). Individual centrality and performance in virtual R&D groups: an empirical study. Journal of Marketing, 54, 68-81.
DiMaggio, P. J., & Powell, W. W.(1983). The Iron Cage Revisited: Institutional Isomorphism and Collective Rationality in Organizational Fields. American Sociological Review, 48, 147-160.
Dodds, W. B., Monroe, K. B., Grewal, D.(1991).Effect of price, brand, and store information on buyers product evaluations. Journal of marketing Research, 28, 307-319.
Edmunds, A., & Morris, A. (2000). The problem of information overload in business organisations: a review of the literature. International Journal of Information Management, 20 , 17-28.
Erdem, T., Swait, J., & Louviere, J. (2002).The Impact of Brand Credibility on Consumer Price Sensitivity.International. Journal of Research in Marketing , 19, 1-19.
Faucheux, C., & Moscovici, S. (1960). Études sur la créativité des groups taches, structures des communications, et`réussite. Bulletin du C. E. R., 9, 11-22.
Feather, J. (1998). In The information society: A study of continuity and change. London: Library Association, 11.
Freeman, L. C. (1977). A set of measures of centrality based on betweenness, Sociometry, 40(1), 35-41.
Freeman, L. C. (1979). Centrality in social networks: Conceptual clarification, Social Networks, 1, 215-239.
Freeman, L. C. (1997). A set of measures of centrality based on betweenness. Sociometry, 40(1), 35-41.
Granovetter, M. (1973). The strength of weak ties: Network theory revisited. American Journal of Sociology, 18 (4), 179-288.
Hansen, M. (1999). The search-transfer problem: The role of weak ties in sharing knowledge across organizational subunits. Administrative Science Quarterly, 44(1), 83–111.
Harary, F. (1969). Graph Theory. Reading Massachusetts.: Addison –Wesley.
Hars, A., & Ou, S. (2002). Working for Free? Motivations for Participating in Open-Source Projects. International Journal of Electronic Commerce, 6(3), 25-39.
Hellevik, O., & Bjørklund, T. (1991). Opinion leadership and political extremism. International Journal of Public Opinion Research, 3, 157-181.
Herd behavior. from http://en.wikipedia.org/wiki/Herd_behavior
Herr, P. M., Kardes, F. R. & Kim, J. (1991). Effects of Word-of-Mouth and Product-Attribute Information on Persuasion: An Accessibility-Diagnosticity Perspective. Journal of Consumer Research , 17.
Jacoby, J., Olson, J. C., & Haddock, R. A. (1917). Price, brand name, and product composition characteristics as determinants of perceived quality. Journal of Applied Psychology,55, 570-579.
Johansson, J. K. (1989). Determinants and Effects of the Use of "Made in" Labels. International Marketing Review, London, 6 (1), 47-59.
John, A. Martilla. (1971). Word-of-Mouth Communication in the Industrial Adoption Process. Journal Marketing Research, 8 (2), 173178.
Jones, M., & Moore M. (1988). Inside organization: Understanding the Human Dimension. Newbury Park, CA: Sage Publications.
Jaw, B. S., & Liu, W. (2003). Promoting organizational learning and self- renewal in Taiwanese companies: The role of HRM. Human Resource Management, 42(3), 223–241.
Kamins, M. A. & Marks, L. J. (1991). The Perception of Kosher as a Third Party Certification Claim in Advertising for Familiar and Unfamiliar Brands. Journal of the Academy of Marketing Science, 19(3) , 177-185.
Katz, E., & Lazarsfeld, P. F. (1955). Personal influence: The part played by people in the flow of mass communication. Glencoe, IL: Free Press.
Kidane, Y. H. & Gloor, P. A. (2007). Correlating temporal communication patterns of the Eclipse open source community with performance and creativity. Comput Math Organiz Theor , 13, 17–27.
Koh, J., Kim, Y.-G., & Kim, Y.-G. (2003). Sense of Virtual Community: A Conceptual Framework and Empirical Validation. International Journal of Electronic Commerce, 8(2), 75-94.
Lampe, C. A. C., Ellison, N., & Steinfield, C. (2007). A familiar face(book): profile elements as signals in an online social network. Paper presented at the Proceedings of the SIGCHI conference on Human factors in computing systems.
Lazarsfeld, P. F., Berelson, B., & Gaudet, H. (1944). The people’s choice: How the voter makes up his mind in a presidential campaign. New York: Columbia University Press.
Leavitt, H. J. (1951). Some effects of certain communication patterns on group performance. Journal of Abnormal & Social Psychology, 46, 38-50.
Lewis, D. (1996). Dying for Information? London: Reuters Business Information, 2.
Lichtenstein, D. R., Ridgway, N. M., & Netemeyer, R. G. (1993). Price perceptions and consumer shopping behavior: A field study. Journal of Marketing Research, 234-245.
Mahajan, V., Muller, E., ＆ Srivastava, R. K. (1990). Determination of adopter categories by using innovation diffusion models. Journal of Marketing Research, 15, 37-50.
McAlexander, J. H., Schouten, J. W., & Koening, H. F. (2002). Building Brand Community, Journal of Marketing, 66(1), pages 38-55.
Merton, R. K. (1968). Patterns of Influence: Local and Cosmopolitan Influential, pages 441-74 in Social Theory and Social Structure, New York: Free Press.
Mitra, A. (1995). Price Cue Utilization in Product Evaluations the Moderating Role of Motivation and Attribute Information. Journal of Business Research, 33, 187-195.
Muncer, S., Loader, B., Burrows R., Pleace N., & Nettleton, S. (2000). Form and Structure of Newsgroups Giving Social Support: A Network Approach. CyberPsychology & Behavior, 3(6), 13.
Prodgers, A. (1999). Identity and the Belonging Group: Personal Integrity in the Changing Organization. Group Analysis, 32(1), 125-137.
Provan, K. G., & Sebastian, J. G. (1998). Networks within Networks: Service Link Overlap, Organizational Cliques, and Network Effectiveness. The Academy of Management Journal, 41(4), 453-463.
Rao, A. R., & Monroe, K. B. (1988). The Moderating Effect of Prior Knowledge on Cue Utilization in Product Evaluations, Journal of Consumer Research, 15, 253-264.
Roch, C. H. (2005). The Dual Roots of Opinion Leadership. Journal of Politics, 67, 110-31.
Rogers, E. (1995). Diffusion of innovations (4th ed.). New York, NY: The Free Press.
Rogers, E. M., & Cartano, D. G. (1962). Methods of measuring opinion leadership. Public Opinion Quarterly, 26, 435-441.
Romm, C., Pliskin, N., & Clarke, R. (1997). Virtual communities and society: toward an integrative three phase model. Academy of Journal of Information Management, 17 (4), 261-70.
Satish Nambisan. (2002). Designing virtual customer environments for new product development: toward a theory. Academy of Management Review, 27(3), 392-413.
Scheufsle D. A., & Shah D. V. (2000). Personality Strength and Social Capital- The Role of Dispositional and Informational Variables in the Production of Civic Participation. Communication Research, 27(2), 107-131.
Schiffman, L. G. & Kanuk, L. L. (2000). Consumer Behavior Hal (IL: Crain book)
Swait, J. (2004). Brand Credibility, Brand Consideration, and Choice Tülin Erdem. Journal of Consumer Research, ABI/INFORM Global, 191.
Social network. (2007). from http://en.wikipedia.org/wiki/Social_network
Thomas W. Valente. (1996). Social network thresholds in the diffusion of innovation. Social networks, 18, 69–89.
Tsai, W. (2002). Social structure of ‘‘coopetition’’ within a multiunit organization: Coordination, competition, and intra-organizational knowledge sharing. Organization Science, 13(2), 179–190.
Valente, T. (1996). Social network thresholds in the diffusion
Valente, T., & Davis, R. (1999). Accelerating the diffusion of innovations using opinion leaders. Annals of the American Academy of Political and Social Science, 566(1), 55–67.
Wasserman, S., & Faust, K. (1994). Social network analysis: methods and applications. New York: Cambridge University Press.
Watts, D. J., & Dodds, P. S. (2007). Influentials, Networks, and Public Opinion Formation. Journal of Consumer Research (in press)
Wellman, B., & Gulia, M. (1999). Net-surfers don’t ride alone: Virtual communities as communities. In B. Wellman (Ed.). Networks in the global village: Life in contemporary communitie , pages 331–366. Boulder, CO7 Westview Press.
Wellman, B., & Gulia, M. (1999). Net-surfers don’t ride alone: Virtual communities as communities. In B. Wellman (Ed.),
Whyte, W. H. (1958). The Web of Word of Mouth’, in Lincoln H. Clark (ed.), Consumer Behavior, 2.