Social media treats all users the same: trusted friend or total stranger, with little or nothing in between. In reality, relationships fall everywhere along this spectrum, a topic social science has investigated for decades under the theme of tie strength. Our work bridges this gap between theory and practice. In this paper, we present a predictive model that maps social media data to tie strength. The model builds on a dataset of over 2,000 social media ties and performs quite well, distinguishing between strong and weak ties with over 85 % accuracy. We complement these quantitative findings with interviews that unpack the relationships we could not predict. The paper concludes by illustrating how modeling tie strength can improve social media design elements, including privacy controls, message routing, friend introductions and information prioritization. Author Keywords Social media, social networks, relationship modeling, ties,

A fundamental principle in social network research is that individuals can benefit from serving as intermediaries between others who are not directly connected. Through such intermediation, they potentially can broker the flow of information and synthesize ideas arising in different parts of the network. These principles form the underpinning for the theory of structural holes, which studies the ways in which individuals, particularly in organizational settings, fill the “holes ” between people or groups that are not otherwise interacting. We apply a game-theoretic approach to this notion, studying the structures that evolve when individuals in a social network have incentives to form links that bridge otherwise disconnected parties. We model payoffs as a trade-off between the benefits of connecting non-neighboring nodes, and the cost, in effort, to maintain links — including settings where the costs are non-uniform to reflect the increased difficulty in spanning different parts of a hierarchical organization. We find, both through theoretical results and computational experiments, that the equilibrium networks in this model have rich combinatorial structure, and capture qualitative observations arising in the study of structural holes. In particular, even in completely symmetric settings, individuals will differentiate themselves in equilibrium, occupying different social strata and receiving correspondingly different payoffs.

A basic issue in social influence is how best to change one’s judgment in response to learning the opinions of others. This article examines the strategies that people use to revise their quantitative estimates on the basis of the estimates of another person. The authors note that people tend to use 2 basic strategies when revising estimates: choosing between the 2 estimates and averaging them. The authors developed the probability, accuracy, redundancy (PAR) model to examine the relative effectiveness of these two strategies across judgment environments. A surprising result was that averaging was the more effective strategy across a wide range of commonly encountered environments. The authors observed that despite this finding, people tend to favor the choosing strategy. Most participants in these studies would have achieved greater accuracy had they always averaged. The identification of intuitive strategies, along with a formal analysis of when they are accurate, provides a basis for examining how effectively people use the judgments of others. Although a portfolio of strategies that includes averaging and choosing can be highly effective, the authors argue that people are not generally well adapted to the environment in terms of strategy selection.

Abstract. In this paper, we summarized recent work in modeling how users socially forage and search for information. One way to bridge between different communities of users is to diversify their information sources. This can be done using not only old mechanisms such as email, instant messages, newsgroups and bulletin boards, but also new ones such as wikis, blogs, social tags, etc. How do users work with diverse hints from other foragers? How do interference effects change their strategies? How can we build tools that help users cooperatively search? We seek theories that might help us answer these questions, or at least point us toward the right directions.

Frankfurt am Main Doctoral Scholarship. Any opinions, findings, and conclusions or

We examine the drivers of diffusion of information through organizations and the effects on performance. In particular, we ask: What predicts the likelihood of an individual becoming aware of a strategic piece of information, or becoming aware of it sooner? Do different types of information exhibit different diffusion patterns, and do different characteristics of social structure, relationships and individuals in turn affect access to different kinds of information? Does better access to information predict an individual’s ability to complete projects or generate revenue? We hypothesize that the dual effects of content and structure jointly predict the diffusion path of information, and ultimately performance. To test our hypotheses, we characterize the social network of a medium sized executive recruiting firm using accounting data on project co-work relationships and ten months of email traffic observed over two five month periods. We identify two distinct types of information diffusing over this network – ‘event news ’ and ‘discussion topics ’ – by their usage characteristics, and observe several thousand diffusion processes of each type of information from their original first use to their varied recipients over time. We then test the effects of network structure and functional and demographic characteristics of dyadic relationships on the likelihood of receiving each type of information and receiving it more quickly. Our results demonstrate that the diffusion of news, characterized by a spike in communication and rapid, pervasive diffusion through the organization, is influenced by demographic and

1 The use of electronic data is steadily gaining ground in the study of the social organization of scientific and research communities, decreasing the researcher’s reliance on commercial databases of bibliographic entries, patents grants and other manually constructed records of scientific works. In our work we provide a method-ological innovation based on semantic technology for dealing with heterogeneity in electronic data sources. We demonstrate the use of our electronic system for data collection and aggregation through a study of the Semantic Web research com-munity. Using methods of network analysis, we confirm the effect of Structural Holes and provide novel explanations of scientific performance based on cognitive diversity in social networks. 1

Although white collar work is of vast importance to the economy, the Operations Management (OM) literature has focused largely on traditional blue collar work. In an effort to stimulate more OM research into the design, control and management of white collar work systems, this paper provides a systematic review of disparate streams of research relevant to understanding white collar work from an operations perspective. Our review classifies research according to its relevance to white collar work at individual, team and organizational levels. By examining the literature in the context of this framework, we identify gaps in our understanding of white collar work which suggest promising research directions.

Effective collaboration dynamics are at the core of learning, knowledge exchange and innovation processes. Nevertheless, in today’s global environment, a large number of collaboration initiatives fail to deliver the value expected, as complexity is increased by the diversity and the distributed nature of the people, groups, and knowledge sources and by the knowledge integration processes involved. Effective collaboration competencies are hence emerging as a key condition for productive and sustainable value creation at the individual, team, organizational and inter-organizational level. L2C- Learning to Collaborate- is an ongoing research project addressing the design of effective immersive simulation-based learning experiences su pporting the development of collaboration competencies both at the individual and organizational level. The key characteristic of such advanced learning tools consists in the integration of psychological, motivational, cognitive, organizational, cultural and technological factors affecting the success or failure of collaboration into the modeling of a set of virtual characters with whom learners can interact dynamically within a challenging and realistic collaboration scenario. This paper provides an overview of the conceptual basis, key design principles and expected pedagogical impact of this new type of immersive simulation-based learning experience.

Please do not redistribute or quote By studying the changes in employees ’ networks and performance before and after the introduction of a social networking tool, I find that a structurally diverse network (low in cohesion and rich in structural holes) has a positive effect on work performance. The size of the effect is smaller than traditional estimates, suggesting that omitted individual characteristics may bias the estimated network effect. I consider two intermediate mechanisms by which a structurally diverse network is theorized to improve work performance: information diversity (instrumental) and social communication (expressive) and quantify their effects on two types of work outcomes: billable revenue and layoffs. Analysis shows that the information diversity derived from a structurally diverse network is more correlated with generating billable revenue than is social communication. However, the opposite is true for layoffs. Friendship, as approximated by social communications, is more correlated with reduced layoff risks than is information diversity. Field interviews suggest that friends can serve as advocates in critical situations, ensuring that favorable information is distributed to decision makers. This, in turn, suggests that having a structurally diverse network can drive both work performance and job security, but that there is a tradeoff between either mobilizing friendship or gathering diverse information. Furthermore, it is important to examine the mechanisms by which social communications reduce the risks of being laid off. If social communications promote team effectiveness, delegating decisions rights to managers is optimal. However, if managers choose to optimize their own power at the expense of the firm, the positive impact of social communications on layoffs is evidence that delegating layoff decisions to managers can incur important costs.