Extrinsic factors refer to incentives provided by external enviro nments. J. de Gruyter.. communication activity. lo ve or affection . The finding sheds new light on the dynamic of 28 peer-to-peer networks and their users. governance and the viability of hybrid forms in open source software development. H. Herbsleb. Organization Science. there might exist alternative explanations for the behaviors. E.. Bock. Journal of Economic Perspectives 14 3 159?C181. and cooperation. However. 30 Bapna.. In this regard. the summary statistics reveal Louis vuitton 48% of all contributors use some form of reward and punishment mechanisms by providing better services to other contributors. we estimate Wait using the average wait Louis Vuitton UK of a user??s download requests. However. Different mechanisms have been proposed in prior studies. but also a social norm that requires compliance. 2005. reciprocity depends on contributors?? needs. Whinston. the punishment and reward mechanism is implemented through server settings. Gu. 2007a . Johnson.. Peer-Enforced Reward and Punishment Mechanism Indirect reciprocity is not onl y a social force that influences individual co ntributions. 2008 Symposium on Statistical Challenges in eCommerce Research SCECR 08 . and J. Contribution costs are largely fixed for an individual. Familiarity. K. Wharton Working Paper. 2005. and G. Tang. S. laboratory experiments show that the responder frequently reciprocates and the amount reciprocated increas es with the original contribution from the proposer Fehr and Schmidt 1999 . H. H4: Reputational incentives - A user??s probability of contribution increases after she Louis Vuitton Outlet special title in recognition of her contribution activities. and J.. 1974. Tables 3 and 4 report the regression results. Johnson. Cunningham. eds. if most individuals decide their leve l of contribution based on obser vations of their neighbors?? contribution behavior. we note that large pee r-to-peer networks often face congestion Asvanund 2004 . ??platinum member??. Studies have shown that these social influences could have significant impacts on individual behaviors and market equilibrium in social networks Fehr and Gachter 2000b; Bapna et al 2003. and K. S. However. from the technical perspective. the value of the reward and punishment mechanism and its influence on others?? behavior s are often not obvious to new users. We infer their motivation from their behaviors. 2000b. Wasko and Faraj 2005 . G. R.. Finally. Oxford University Press.. Mike Smith and seminar participants at the University of Texas Louis vuitton uk Austin. In the context of social networks. religion belief. K. R.. J. M. B. Why should i sh are? Examining knowledge contribution in electronic networks of practice. indicating that some of the Value Users do not contribute daily. J. B. As the p eer-to-peer network studie d in this paper allows 14 contributors to punish free riders and reward contributors. Han.D.. a key f eature of these networks is th at a contributor can determine whether. 2001a. and T. Rockenbach. Proceedings of Academy of Management Conference. A. Hawaii. Kahneman. Kartik Hosanagar. and Sen. 2001b. By studying how louis vuitton outlet change server settings with the social environment. individuals are less likely to reciprocate to these contributors in kind. 2006 Despite the large number of mo tivation factors identified in prior studies. and R. Tang. 1987. Table 3 reports the social influence of indirect reciprocity on the individual c ontribution. Ledyard. and S. A. These concerns vary significantly across individuals but remain mostly unchanged over time for a given individual. 2005. They are willing to sacrifice private gain to reward pro-social behaviors and to punish free riders Clark and Sefton 2001. louis vuitton outlet The percentage is higher than the percentage of all contributors. and H. Saroiu. In a well-known public good experiment conducted by Fehr and Gachter 2000b . R. Bock. M. This social enforcement mechanism provides an important tool to punish free riders and reward contributors. Kraut. 2008 . Familiarity. This proposition is. However. C. 2004. 2004. Information Systems Research 15 2 155-174. Emerson. Incentive mechanisms are important for the enforcement of social norms. E. Kuk 2006.