Social networks are social structures composed of groups of people, which are connected by one or more types of relationships such as friendship, Relationship, common interests and shared knowledge.

Social network analysis examines the social structure by applying the Graph Theory and identifying the entities as "nodes" or "points" and relationships as "links" or "edges." The structure of the graph result is often very complex . As mentioned, there may be many kinds of ties between nodes. The multidisciplinary research has shown that social networks operate on many levels, from family relationships to relationships statewide organizations (in this case we speak of political networks ), play a critical role in determining the political agenda the extent to which individuals or organizations achieve their objectives or are influenced.

In its simplest form, a social network is a map of all the relevant links between all nodes studied. We speak here of networks "sociocentric" or "complete." Another option is to identify the network that involves a person (in different social contexts in which it interacts), in which case we speak of "personal network."

The network can also be used to measure social capital (ie the value that an individual gets the resources available through its network). These concepts are shown, often in a diagram where the nodes are points and loops, lines.

Social network analysis

Example of a diagram of a network. The node with the highest centrality intermediation is marked in yellow.
The social network analysis (related to network theory ) has emerged as a key approach in modern social sciences , among which include sociology , the anthropology , the social psychology , the economy , the geography , the political sciences , the scientometrics , communication studies, organizational studies and sociolinguistics . He has also won significant support in physics and biology among others.

In everyday language was used freely the idea of "social network" for over a century to denote complex sets of relationships between members of social systems in all dimensions, from the interpersonal to the international level. In 1954, anthropologist JA Barnes Manchester School began using the term systematically to show patterns of loops, covering the concepts traditionally used by social scientists: groups defined (eg, tribes, families) and categories social (eg, gender , ethnicity). Scholars such as SD Berkowitz, Stephen Borgatti, Ronald Burt Burt , Kathleen Carley Carley , Martin Everett, Katherine Faust, Linton Freeman, Mark Granovetter Granovetter , David Knoke, Krackhardt David Krackhardt , Peter Marsden, Nicholas Mullins, Anatol Rapoport Rapoport , Stanley Wasserman, Wellman Barry Wellman , R. Douglas R. White White and White Harrison White expanded the use of systematic social network analysis.

Analysis of social networks has grown from a suggestive metaphor to become an analytical approach and a paradigm, with its theoretical principles, methods, network analysis software software for social network analysis and research lines themselves. Analysts studying the influence of all the parts and vice versa, the effect of the selective action of individuals in the network, from structure to the relationship and the individual, from behavior to attitudes. As such these tests are done well in complete networks, where links are specific relationships in a defined population, or in personal networks (also known as egocentric networks, while not exactly comparable), where he studied "personal communities . The distinction between total networks / comprehensive and personal networks / egocentric depends much more on the analyst's ability to collect data and information. That is, for groups such as businesses, schools or companies with membership, he expects to have full information about who is on the network, all of egos and alters the potential participants. Personal studies / egocentric are usually conducted when the identities or egos known, but not his alters. These studies allow egos to provide information on the identity of their alters and there is an expectation that the different egos or alters sets are linked with each other.

A network built from a snowball refers to the idea that the alters are identified in a survey by a set of initial Egos (zero tide) and the same alters egos become at wave 1 and appoint other Additional alters and so on until the percentage of new alters begins to decrease. Although there are several logistical limits in conducting studies snowball recent development is to consider hybrid networks, which provides complete network egos can nominate alters who otherwise would not be identified, allowing them to be visible to all egos of the network. The hybrid network can be valuable to examine total network / full on which are the major players include expectation beyond the formally identified. For example, company employees often work with outside consultants who are part of a network that can not be fully defined before data collection.

In social network analysis, presents several analytical trends:
No part of the hypothesis that the groups are the building blocks in society: the approach is open to studying less defined social systems, from community non-local to links through websites .
Rather than treating individuals (persons, organizations, states) as discrete units of analysis focuses on how the structure of relations affects individuals and their relationships.
In contrast to the analysis assuming that the socialization of norms determines behavior, network analysis is used to observe the extent to which the structure and composition of the relations between individuals affect the rules.

The shape of a social network helps determine the usefulness of the network for its members. Smaller networks and more stringent, may be less useful to its members that the networks with a lot of loose connections ( weak link ) with people outside the main network. More open networks with many weak ties and social relations are more likely to present new ideas and opportunities for its members that closed networks with many redundant ties. In other words, a group of friends who only do things with each other and share the same knowledge and opportunities. A group of individuals with connections to other social worlds is likely to have access to a wider range of information. It is better for individual success to have connections with a variety of networks instead of many connections on a single network. Similarly, individuals can exercise influence or act as intermediaries in their social networks, a bridge between two networks that are not directly linked (called filling structural holes).

The power of social network analysis lies in its difference from traditional studies in the social sciences, which assume that the attributes of individual actors-whether friendly or unfriendly, smart or dumb, etc.-is what matters. Social network analysis produces a vision both alternative and complementary, in which the attributes of individuals are less important than their relationships and linkages with other actors within the network. This approach has proved useful for explaining many real-world phenomena, but leaves less room for individual action and the ability of individuals to influence their success as largely based on the structure of your network.

Social networks have also been used to examine how organizations interact with each other, characterizing the many informal connections that link executives to each other, as well as associations and connections between employees of different organizations. For example, power within organizations often comes more from the degree to which an individual within a network is in the center of many relationships that their real job. Social networks also play a key role in recruitment within the commercial success and job performance. Networks are ways in which businesses collect information, discourage competition and collusion in setting prices or policies. Android app