Elisa Jayne Bienenstock

The core as a solution to exclusionary networks

Abstract The core is a game theory solution concept that is applicable to exclusionary (negatively connected) exchange networks. The core makes only the minimal assumptions of individual and coalitional rationality. The core describes who should exchange with whom and what the terms of the exchanges should be. Unlike other algorithms that have been applied to exclusionary exchange networks, the core applies to a wider variety of problems than any single competing procedure previously proposed. It can easily be extended to handle a variety of situations: more than one exchange per round; relationships having unequal values; positions having sources of reward other than exchange; and situations where more than one exchange is required. Moreover, networks in which the core is empty should experience particular difficulty in reaching agreement about exchanges.

When Rationality Fails Unstable Exchange Networks with Empty Cores

Power differences within networks can arise when some positions have many alternative transaction partners who themselves have few alternatives. Recent social psychological models developed to predict power in these situations have assumed that stable transaction patterns will emerge in these networks. These models depend on the assumption that stable exchange patterns will develop. Using the game theoretic concept of the core, we show that in some networks, stable patterns should not emerge. Who transacts with whom and terms of the transaction should never reach equilibrium. Three types of instability are distinguished in this article: unreliability, insecurity, and variety. These types of instability are affected by the existence and size of the core. Experiments and simulations comparing networks with and without core solutions and with different-sized cores show that the predicted differences exist.

Women's participation in the labor force: the role of social networks

Network research about employment outcomes has rarely focused on women. In this paper, we use the Los . Angeles Survey of Urban Inequality LASUI to examine the role of social networks on the constraints and opportunities which women face in labor force participation. We examine the effects of a womans general network structure on her employment status, rather than focusing on the characteristics of the specific network tie that connected her to a job. Using an innovative, yet simple, measure to capture network diversity, we test network explanations of why women are in the paid labor force, controlling for background, structural, and family composition variables. In general, we find that the greater the quality and diversity of the social resources that are available through a womans social network, the more likely she is to be working for pay. We also find evidence that suggests disadvantaged women with children must also rely on their social support networks for childcare to enter the labor market. In addition, we explore the connection between the methods successful job searchers used to find work and the overall structure of their networks through descriptive statistics. q 1999 Elsevier Science B.V. All rights reserved.

Social networks reveal cultural behaviour in tool-using dolphins

Animal tool use is of inherent interest given its relationship to intelligence, innovation and cultural behaviour. Here we investigate whether Shark Bay bottlenose dolphins that use marine sponges as hunting tools (spongers) are culturally distinct from other dolphins in the population based on the criteria that sponging is both socially learned and distinguishes between groups. We use social network analysis to determine social preferences among 36 spongers and 69 non-spongers sampled over a 22-year period while controlling for location, sex and matrilineal relatedness. Homophily (the tendency to associate with similar others) based on tool-using status was evident in every analysis, although maternal kinship, sex and location also contributed to social preference. Female spongers were more cliquish and preferentially associated with other spongers over non-spongers. Like humans who preferentially associate with others who share their subculture, tool-using dolphins prefer others like themselves, strongly suggesting that sponge tool-use is a cultural behaviour.

Game-Theory Models for Exchange Networks: Experimental Results

The goal of current exchange-network literature is to develop algorithms, loosely based on rational choice, that predict how resources are distributed through exchange networks and which positions have power to accumulate resources. These objectives closely resemble those of N-person cooperative games with transferable utility, which are based on formal explicit models of rational choice. Experimentally, power is exhibited when a position can amass a favorable proportion of available resources by negotiating a division with another network member. Game-theory solution concepts that address the question of power in networks are introduced and compared to network-exchange models to evaluate the effectiveness of the game-theory solutions and those of exchange theory in predicting results observed in experiments. Experimental data show that there is a utility in incorporating game theory into the discussion of exchange in negatively connected networks. Furthermore, the use of game theory leads to a more comprehensive understanding of many processes to which exchange theory is insensitive.

A Typology for Understanding the Connections Among Different Forms of Social Capital

Critics have argued that the term social capital is too vague or general to be a useful concept. Recognizing the need for clarification, the authors distill the conceptual discussions about social capital to argue that there are three components_network structure, trust and reciprocity, and resources_that are associated with but vary in degree and salience for all forms of social capital. These three components should be considered continua along which the forms of social capital can vary. A fourth continuum is between micro and macro levels of social capital. Locating particular examples of social capital along these continua opens the possibility to compare different types of social capital and to develop and test theories about how they are related to each other. The authors also describe a simulation study to illustrate how simulation can facilitate understanding of the linkages among different forms of social capital.

NETWORK EXCHANGE AS A COOPERATIVE GAME

This paper presents parallels between network exchange experiments and N-person cooperative games with transferable utility, to show how game theory can assist network exchange researchers, not only in predicting outcomes, but in properly specifying the scope of their models. It illustrates how utility, strategy and c-games, concepts found in game theory, could be used by exchange theorists to help them reflect on their models and improve their research design. One game theoretic solution concept, the kernel, is compared to recent network exchange algorithms as an illustration of how easy it is to apply game theory to the exchange network situation. It also illustrates some advantages of using a game theory solution concept to model network exchange.

Bridging Social Networks and Female Labor- Force Participation in a Multiethnic Metropolis.

Using data from a multi-city survey of urban inequality, we assess the effects of bridging social networks—ties that connect individuals to different worlds of information, resources, and opportunities—on Black, Hispanic, and White female labor-force participation in metropolitan Los Angeles. Our findings indicate that these types of networks are far more important in explaining the labor-market experiences of females in Los Angeles than the kinds of cultural forces that serve as the foundation of much contemporary conservative social policy making in the United States. Implications for current efforts to transition women from welfare to work are discussed.

The effect of network density and homogeneity on attitude polarization

This paper analyzes data from the 1985 General Social Survey to determine if network homogeneity and density magnify social and political attitude differences between racial, gender, educational and religious categories. Network heterogeneity and density both have the predicted effect on attitude differences. The results vindicate the continued interests of social scientists in the role of social networks in the development and transmission of political attitudes.

An empirical test of the cultural capital hypothesis

Using data from the Multi-City Survey of Urban Inequality, an exploratory, empirical analysis of the cultural capital hypothesis was conducted. The analyses indicate that, while the types of cultural influences cited by proponents of this thesis clearly have negative effects on employment when viewed in isolation from other factors, they are not significant when statistical controls for human capital variables are incorporated into the model. Our findings suggest the need to invest more resources in the public education system and in efforts to combat racial discrimination in the labor market.