Analysis of Herding on the Internet - An Empirical Investigation of Online Software Download

Online shopping often requires consumers to choose among multiple products without detailed information about the quality. Herding is common in situations where consumers infer product quality from other consumers’ choices and incorporate that information into their own decision-making process. The Internet affects the herding phenomenon in two ways. On the one hand, it provides more information about other consumers’ choices, therefore making herding more feasible. On the other hand, it provides more details about product quality, thus making herding less desirable. This paper empirically examines those two effects in the context of online software downloading. We find significant herd behavior in our analysis, and, surprisingly, the provision of professional product reviews or user reviews does not significantly influence the herding phenomenon. This study contributes to the E-Commerce and the Internet marketing research by investigating online consumer behavior. This paper also contributes to the emerging literature of studying the impact of virtual communities

Indirect Reciprocity in Contributions to a Peer-to-Peer Music Sharing Network - An Empirical Analysis of Individual Level Data

This study assesses the influence of indirect reciprocity on individual contribution to a peer-to-peer network. We find that individuals’ level of contributions increases with number of contributors in the peer-to-peer network but decrease with number of free riders in the networks, indicating that individual contributions are reciprocal in nature. Moreover, we show that individuals have strong incentive to punish free riders and reward contributors in the peer-to-peer network. They do so through the setting of servers that allows discrimination among downloaders. When number of free riders increases, individuals are more likely to change the server settings to provide priority services to contributors and lesser services to free riders. The phenomena are consistent with findings from economic experiments which suggest that reciprocity and the ability to punish free riders could sustain contribution to pubic goods. The findings have important implications on the design and practical management of peer-to-peer networks

Do online reviews matter? — An empirical investigation of panel data

This study examines the persuasive effect and awareness effect of online user reviews on movies' daily box office performance. In contrast to earlier studies that take online user reviews as an exogenous factor, we consider reviews both influencing and influenced by movie sales. The consideration of the endogenous nature of online user reviews significantly changes the analysis. Our result shows that the rating of online user reviews has no significant impact on movies' box office revenues after accounting for the endogeneity, indicating that online user reviews have little persuasive effect on consumer purchase decisions. Nevertheless, we find that box office sales are significantly influenced by the volume of online posting, suggesting the importance of awareness effect. The finding of awareness effect for online user reviews is surprising as online reviews under the analysis are posted to the same website and are not expected to increase product awareness. We attribute the effect to online user reviews as an indicator of the intensity of underlying word-of-mouth that plays a dominant role in driving box office revenues.Accepted manuscrip

Content Contribution under Revenue Sharing and Reputation Concern in Social Media: The Case of YouTube

A key feature of social media is that it allows individuals and businesses to contribute contents for public viewing. However, little is known about how content providers derive payoffs from such activities. In this study, we build a dynamic structural model to recover the utility function for content providers. Our model distinguishes short-term payoffs based on ad revenue sharing from long-term payoffs driven by content providers’ reputation. The model was estimated using a panel data of 914 top 1000 providers and 381 randomly selected providers on YouTube from Jun 7th, 2010, to Aug 7th, 2011. The two different sets of providers allow us to explore the difference between top and ordinary providers. Our results demonstrate that both providers value incremental subscribers as much as incremental video views. We also find that top providers value accumulative subscribers more than accumulative video views, while ordinary providers value accumulative video views more

The dynamics of online word-of-mouth and product sales—an empirical investigation of the movie industry

There are growing interests in understanding how word-of-mouth (WOM) on the Internet is generated and how it influences consumers’ purchase decisions at retail outlets. A unique aspect of the WOM effect is the presence of a positive feedback mechanism between WOM and retail sales. We characterize the process through a dynamic simultaneous equation system, in which we separate the effect of online WOM as both a precursor to and an outcome of retail sales. We apply our approach to the movie industry, showing that both a movie's box office revenue and WOM valence significantly influence WOM volume. WOM volume in turn leads to higher box office performance. This positive feedback mechanism highlights the importance of WOM in generating and sustaining retail revenue.Accepted manuscrip

Quantum three-body system in D dimensions

The independent eigenstates of the total orbital angular momentum operators for a three-body system in an arbitrary D-dimensional space are presented by the method of group theory. The Schr\"{o}dinger equation is reduced to the generalized radial equations satisfied by the generalized radial functions with a given total orbital angular momentum denoted by a Young diagram $[\mu,\nu,0,...,0]$ for the SO(D) group. Only three internal variables are involved in the functions and equations. The number of both the functions and the equations for the given angular momentum is finite and equal to $(\mu-\nu+1)$.Comment: 16 pages, no figure, RevTex, Accepted by J. Math. Phy

Independent Eigenstates of Angular Momentum in a Quantum N-body System

The global rotational degrees of freedom in the Schr\"{o}dinger equation for an $N$-body system are completely separated from the internal ones. After removing the motion of center of mass, we find a complete set of $(2\ell+1)$ independent base functions with the angular momentum $\ell$. These are homogeneous polynomials in the components of the coordinate vectors and the solutions of the Laplace equation, where the Euler angles do not appear explicitly. Any function with given angular momentum and given parity in the system can be expanded with respect to the base functions, where the coefficients are the functions of the internal variables. With the right choice of the base functions and the internal variables, we explicitly establish the equations for those functions. Only (3N-6) internal variables are involved both in the functions and in the equations. The permutation symmetry of the wave functions for identical particles is discussed.Comment: 24 pages, no figure, one Table, RevTex, Will be published in Phys. Rev. A 64, 0421xx (Oct. 2001

GPU-based Iterative Cone Beam CT Reconstruction Using Tight Frame Regularization

X-ray imaging dose from serial cone-beam CT (CBCT) scans raises a clinical concern in most image guided radiation therapy procedures. It is the goal of this paper to develop a fast GPU-based algorithm to reconstruct high quality CBCT images from undersampled and noisy projection data so as to lower the imaging dose. For this purpose, we have developed an iterative tight frame (TF) based CBCT reconstruction algorithm. A condition that a real CBCT image has a sparse representation under a TF basis is imposed in the iteration process as regularization to the solution. To speed up the computation, a multi-grid method is employed. Our GPU implementation has achieved high computational efficiency and a CBCT image of resolution 512\times512\times70 can be reconstructed in ~5 min. We have tested our algorithm on a digital NCAT phantom and a physical Catphan phantom. It is found that our TF-based algorithm is able to reconstrct CBCT in the context of undersampling and low mAs levels. We have also quantitatively analyzed the reconstructed CBCT image quality in terms of modulation-transfer-function and contrast-to-noise ratio under various scanning conditions. The results confirm the high CBCT image quality obtained from our TF algorithm. Moreover, our algorithm has also been validated in a real clinical context using a head-and-neck patient case. Comparisons of the developed TF algorithm and the current state-of-the-art TV algorithm have also been made in various cases studied in terms of reconstructed image quality and computation efficiency.Comment: 24 pages, 8 figures, accepted by Phys. Med. Bio