Overview[ edit ] Evolution graph of a social network: The social network is a theoretical construct useful in the social sciences to study relationships between individuals, groups , organizations , or even entire societies social units , see differentiation. The term is used to describe a social structure determined by such interactions. The ties through which any given social unit connects represent the convergence of the various social contacts of that unit. This theoretical approach is, necessarily, relational.
An axiom of the social network approach to understanding social interaction is that social phenomena should be primarily conceived and investigated through the properties of relations between and within units, instead of the properties of these units themselves.
Thus, one common criticism of social network theory is that individual agency is often ignored  although this may not be the case in practice see agent-based modeling.
Precisely because many different types of relations, singular or in combination, form these network configurations, network analytics are useful to a broad range of research enterprises. In social science, these fields of study include, but are not limited to anthropology , biology , communication studies , economics , geography , information science , organizational studies , social psychology , sociology , and sociolinguistics.
Moreno began systematic recording and analysis of social interaction in small groups, especially classrooms and work groups see sociometry. Barnes ,  J. Clyde Mitchell and Elizabeth Bott Spillius ,   often are credited with performing some of the first fieldwork from which network analyses were performed, investigating community networks in southern Africa, India and the United Kingdom.
Nadel codified a theory of social structure that was influential in later network analysis. Also independently active in the Harvard Social Relations department at the time were Charles Tilly , who focused on networks in political and community sociology and social movements, and Stanley Milgram , who developed the "six degrees of separation" thesis. Christakis , James H. Fowler , and others, developing and applying new models and methods to emerging data available about online social networks, as well as "digital traces" regarding face-to-face networks.
However, a global network analysis  of, for example, all interpersonal relationships in the world is not feasible and is likely to contain so much information as to be uninformative.
Practical limitations of computing power, ethics and participant recruitment and payment also limit the scope of a social network analysis. Thus, social networks are analyzed at the scale relevant to the researcher's theoretical question. Although levels of analysis are not necessarily mutually exclusive , there are three general levels into which networks may fall: Micro level[ edit ] At the micro-level, social network research typically begins with an individual, snowballing as social relationships are traced, or may begin with a small group of individuals in a particular social context.
A dyad is a social relationship between two individuals. Network research on dyads may concentrate on structure of the relationship e. Add one individual to a dyad, and you have a triad. The discord in a rivalrous love triangle is an example of an unbalanced triad, likely to change to a balanced triad by a change in one of the relations. The dynamics of social friendships in society has been modeled by balancing triads.
The study is carried forward with the theory of signed graphs. The smallest unit of analysis in a social network is an individual in their social setting, i. Egonetwork analysis focuses on network characteristics such as size, relationship strength, density, centrality , prestige and roles such as isolates, liaisons , and bridges. Subset levels of network research problems begin at the micro-level, but may cross over into the meso-level of analysis.
Subset level research may focus on distance and reachability, cliques , cohesive subgroups, or other group actions or behavior. However, meso-level may also refer to analyses that are specifically designed to reveal connections between micro- and macro-levels.
Meso-level networks are low density and may exhibit causal processes distinct from interpersonal micro-level networks. Formal organizations are social groups that distribute tasks for a collective goal.
Intra-organizational networks themselves often contain multiple levels of analysis, especially in larger organizations with multiple branches, franchises or semi-autonomous departments.
In these cases, research is often conducted at a workgroup level and organization level, focusing on the interplay between the two structures. Exponential random graph models of social networks became state-of-the-art methods of social network analysis in the s.
This framework has the capacity to represent social-structural effects commonly observed in many human social networks, including general degree -based structural effects commonly observed in many human social networks as well as reciprocity and transitivity , and at the node-level, homophily and attribute -based activity and popularity effects, as derived from explicit hypotheses about dependencies among network ties.
Parameters are given in terms of the prevalence of small subgraph configurations in the network and can be interpreted as describing the combinations of local social processes from which a given network emerges. These probability models for networks on a given set of actors allow generalization beyond the restrictive dyadic independence assumption of micro-networks, allowing models to be built from theoretical structural foundations of social behavior. Each graph has 32 nodes and 32 links.
Note the "hubs" shaded in the scale-free diagram on the right. A scale-free network is a network whose degree distribution follows a power law , at least asymptotically.
In network theory a scale-free ideal network is a random network with a degree distribution that unravels the size distribution of social groups.
One notable characteristic in a scale-free network is the relative commonness of vertices with a degree that greatly exceeds the average. The highest-degree nodes are often called "hubs", and may serve specific purposes in their networks, although this depends greatly on the social context. Another general characteristic of scale-free networks is the clustering coefficient distribution, which decreases as the node degree increases.
This distribution also follows a power law. Macro level[ edit ] Rather than tracing interpersonal interactions, macro-level analyses generally trace the outcomes of interactions, such as economic or other resource transfer interactions over a large population.
Large-scale network is a term somewhat synonymous with "macro-level" as used, primarily, in social and behavioral sciences, in economics. Originally, the term was used extensively in the computer sciences see large-scale network mapping.
Most larger social networks display features of social complexity , which involves substantial non-trivial features of network topology , with patterns of complex connections between elements that are neither purely regular nor purely random see, complexity science , dynamical system and chaos theory , as do biological , and technological networks. Such complex network features include a heavy tail in the degree distribution , a high clustering coefficient , assortativity or disassortativity among vertices, community structure see stochastic block model , and hierarchical structure.
In the case of agency-directed networks these features also include reciprocity , triad significance profile TSP, see network motif , and other features. In contrast, many of the mathematical models of networks that have been studied in the past, such as lattices and random graphs , do not show these features. The most prominent of these are Graph theory , Balance theory , Social comparison theory , and more recently, the Social identity approach.
The basis of Heterophily Theory was the finding in one study that more numerous weak ties can be important in seeking information and innovation, as cliques have a tendency to have more homogeneous opinions as well as share many common traits. This homophilic tendency was the reason for the members of the cliques to be attracted together in the first place.
However, being similar, each member of the clique would also know more or less what the other members knew. To find new information or insights, members of the clique will have to look beyond the clique to its other friends and acquaintances.
This is what Granovetter called "the strength of weak ties". Contacts in a network provide information, opportunities and perspectives that can be beneficial to the central player in the network. Most social structures tend to be characterized by dense clusters of strong connections. Non-redundant information is most often obtained through contacts in different clusters. An ideal network structure has a vine and cluster structure, providing access to many different clusters and structural holes.
The main player in a network that bridges structural holes is able to access information from diverse sources and clusters. This concept is similar to Mark Granovetter's theory of weak ties , which rests on the basis that having a broad range of contacts is most effective for job attainment. Communication[ edit ] Communication Studies are often considered a part of both the social sciences and the humanities, drawing heavily on fields such as sociology , psychology , anthropology , information science , biology , political science , and economics as well as rhetoric , literary studies , and semiotics.
Many communication concepts describe the transfer of information from one source to another, and can thus be conceived of in terms of a network. Community[ edit ] In J. Barnes' day, a " community " referred to a specific geographic location and studies of community ties had to do with who talked, associated, traded, and attended church with whom. Today, however, there are extended "online" communities developed through telecommunications devices and social network services.
Such devices and services require extensive and ongoing maintenance and analysis, often using network science methods. Community development studies, today, also make extensive use of such methods. Complex networks[ edit ] Complex networks require methods specific to modelling and interpreting social complexity and complex adaptive systems , including techniques of dynamic network analysis.
Mechanisms such as Dual-phase evolution explain how temporal changes in connectivity contribute to the formation of structure in social networks. Criminal networks[ edit ] In criminology and urban sociology , much attention has been paid to the social networks among criminal actors. For example, Andrew Papachristos  has studied gang murders as a series of exchanges between gangs.
Murders can be seen to diffuse outwards from a single source, because weaker gangs cannot afford to kill members of stronger gangs in retaliation, but must commit other violent acts to maintain their reputation for strength. Diffusion of innovations[ edit ] Diffusion of ideas and innovations studies focus on the spread and use of ideas from one actor to another or one culture and another.
This line of research seeks to explain why some become "early adopters" of ideas and innovations, and links social network structure with facilitating or impeding the spread of an innovation. Demography[ edit ] In demography , the study of social networks has led to new sampling methods for estimating and reaching populations that are hard to enumerate for example, homeless people or intravenous drug users. For example, respondent driven sampling is a network-based sampling technique that relies on respondents to a survey recommending further respondents.
Economic sociology[ edit ] The field of sociology focuses almost entirely on networks of outcomes of social interactions.
More narrowly, economic sociology considers behavioral interactions of individuals and groups through social capital and social "markets". Sociologists, such as Mark Granovetter, have developed core principles about the interactions of social structure, information, ability to punish or reward, and trust that frequently recur in their analyses of political, economic and other institutions. Granovetter examines how social structures and social networks can affect economic outcomes like hiring, price, productivity and innovation and describes sociologists' contributions to analyzing the impact of social structure and networks on the economy.
The scientific philosophy of human ecology has a diffuse history with connections to geography , sociology , psychology , anthropology , zoology , and natural ecology. Literary networks[ edit ] In the study of literary systems, network analysis has been applied by Anheier, Gerhards and Romo,  De Nooy,  and Senekal,  to study various aspects of how literature functions. The basic premise is that polysystem theory, which has been around since the writings of Even-Zohar , can be integrated with network theory and the relationships between different actors in the literary network, e.