Journal of Management Information Systems / Summer 2008, Vol. 25, No. 1, pp. 49–78. © 2008 M.E. Sharpe, Inc. 0742–1222 / 2008 $9.50 + 0.00. DOI 10.2753/MIS0742-1222250103 Stylometric Identification in Electronic Markets: Scalability and Robustness AHMED ABBASI, HSINCHUN CHEN, AND JAY F. NUNAMAKER JR. AHMED ABBASI is a Professor in the Sheldon B. Lubar School of Business at the Uni- versity of Wisconsin–Milwaukee. He received his Ph.D. in Management Information Systems from the University of Arizona and an MBA and B.S. in Information Tech- nology from Virginia Tech. His research interests include application of text mining and information visualization techniques for improved online trust and analysis within electronic markets and computer-mediated communication. His research has appeared in IEEE Intelligent Systems, ACM Transactions on Information Systems, and various conferences, including the ACM/IEEE Joint Conference on Digital Libraries. HSINCHUN CHEN is McClelland Professor of Management Information Systems at the University of Arizona. He received a B.S. from the National Chiao-Tung University in Taiwan, an MBA from SUNY Buffalo, and a Ph.D. in Information Systems from New York University. Dr. Chen is a Fellow of IEEE and AAAS. He received the IEEE Computer Society 2006 Technical Achievement Award. He is author/editor of 13 books, 17 book chapters, and more than 130 Science Citation Index journal articles covering digital library, intelligence analysis, biomedical informatics, data/text/Web mining, knowledge management, and Web computing. He serves on ten editorial boards and has served as a scientific counselor/advisor of the National Library of Medicine. He has been an advisor for major research programs in digital library, digital government, medical informatics, and national security research. JAY F. NUNAMAKER JR. is Regents and Soldwedel Professor of MIS, Computer Science and Communication, and Director of the Center for the Management of Information at the University of Arizona, Tucson. He received his Ph.D. in systems engineering and operations research from Case Institute of Technology, an M.S. and B.S. in engineering from the University of Pittsburgh, and a B.S. from Carnegie Mellon University. Dr. Nunamaker received the LEO Award from the Association of Information Systems at ICIS in Barcelona, Spain, December 2002. This award is given for a lifetime of exceptional achievement in information systems. He was elected as a fellow of the Association of Information Systems in 2000. Dr. Nunamaker has over 40 years of experience in examining, analyzing, designing, testing, evaluating, and developing information systems. He has served as a test engineer at the Shippingport Atomic Power facility, as a member of the ISDOS team at the University of Michigan, and as a member of the faculty at Purdue University, prior to joining the faculty at the University of Arizona in 1974. His research on group support systems addresses behavioral as well as engineering issues and focuses on theory as well as implementation. He has been a licensed professional engineer since 1965. ABSTRACT: Online reputation systems are intended to facilitate the propagation of word of mouth as a credibility scoring mechanism for improved trust in electronic