Modeling User Reputation in Online Social Networks: The Role of Costs, Benefits, and Reciprocity.

Frank Schweitzer,Adrian M Seufert,David Garcia,Pavlin Mavrodiev

doi:10.3390/e22101073

Abstract

We analyze an agent-based model to estimate how the costs and benefits of users in an online social network (OSN) impact the robustness of the OSN. Benefits are measured in terms of relative reputation that users receive from their followers. They can be increased by direct and indirect reciprocity in following each other, which leads to a core-periphery structure of the OSN. Costs relate to the effort to login, to maintain the profile, etc. and are assumed as constant for all users. The robustness of the OSN depends on the entry and exit of users over time. Intuitively, one would expect that higher costs lead to more users leaving and hence to a less robust OSN. We demonstrate that an optimal cost level exists, which maximizes both the performance of the OSN, measured by means of the long-term average benefit of its users, and the robustness of the OSN, measured by means of the lifetime of the core of the OSN. Our mathematical and computational analyses unfold how changes in the cost level impact reciprocity and subsequently the core-periphery structure of the OSN, to explain the optimal cost level.

Highlights

Online social networks (OSN), like other types of social organizations, undergo a steady evolution.This is caused by the behavior of users while using the network [1], but even more if new users enter the network, while other users may decide to leave
We build on the existing model class, but extend it in several important points: (i) In contrast to the simple extremal dynamics, we introduce a condition for users to decide to leave, namely we allow many more users to leave dependent on their personal cost-benefit ratio. (ii) We focus on the effects that cascades of users leaving have on the robustness and the performance of the online social network (OSN)
How should one measure the “performance” of an OSN? Users join the OSN for a purpose and, as we have explained in Section 2.1, here we assume that the benefits of users can be measured in terms of their relative reputation, which should be possibly increased

Summary

Introduction

Online social networks (OSN), like other types of social organizations, undergo a steady evolution. This is caused by the behavior of users while using the network [1], but even more if new users enter the network, while other users may decide to leave. New links between users are formed online, based on shared information, friendship, common interests, etc., and existing links may be deleted if users leave, or commonalities have changed. Under normal circumstances, such events may not jeopardize the existence of the OSN, in particular if the OSN is still popular and growing. As a recent empirical study [2] has shown, the dropout of some users can trigger cascades of other users leaving, which quickly accumulates to a level that threatens the existence of the OSN

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