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1 "Introduction in Social Network Analysis
"Introduction in Social Network Analysis. Theoretical Approaches and Empirical Analysis with computer-assisted programmes." Dr. Denis Gruber State University of St. Petersburg Faculty of Sociology DAAD-Lecturer for Sociology 1

2 2

3 What is a network? Definition:
„(...) a specific set of linkages among a defined set of persons with the additional property that the characteristics of these linkages as a whole may be used to interpret the social behavior of the persons involved.“ (Mitchell 1969:2) Primary literature: Wasserman, Stanley / Faust, Katherine (2008): Social Network Analysis. Methods and Applications, Cambridge, University Press 3

4 What is Social Network Analysis?
“(…) is based on an assumption of the importance of relationships among interacting units“ (Wasserman/Faust 2008:4) “(…) encompasses theories, models, and applications that are expressed in terms of relational concepts or processes” (Wasserman/Faust 2008:4) “(…) the unit of analysis in network analysis is not the individual, but an entity consisting of a collection of individuals and the linkages among them” (Wasserman/Faust 2008:5) Network methods focus on: Dyads (two actors and their ties) Triads (three actors and their ties) Larger systems (subgroups of individuals, or entire networks) 4

5 Principles of Social Network Analysis
Actors and their actions are viewed as interdependent rather than independent, autonomous units Relational ties (linkages) between actors are channels for transfer or “flow” of resources (either material or nonmaterial) Network models focusing on individuals view the network structure environment as providing opportunities for or constraints on individual action Network models conceptualize structure (social, economic, political, and so forth) as lasting patterns of relations among actors (Wasserman/Faust 2008:4) 5

6 The Social Network Approach
The world is composed of networks - not densely-knit, tightly-bounded groups Networks provide flexible means of social organization and of thinking about social organization Networks have emergent properties of structure and composition Networks are a major source of social capital Networks are self-shaping and reflexive Networks scale up to networks of networks 6

7 Overview about the development of Social Network Analsis
1930 1950/60 Simmel: Soziologie sollte sich – statt den Inhalten – den Formen der Vergesellschaftung durch eben diese Wechselwirkungen widmen(Beziehungen zwischen Individuen rückten ins Zentrum) 1933 Der Psychologen Moreno (der späteren Begründer des “Psychodramas”) stellt die Soziometrie (visuelle Darstellung von Beziehungen) erstmals als wiss. Methode auf einem Medizinischen Kongreß vor. 1970 (Scott 1991, 7) 7

8 Which differences exist between a social network analysis and a non-network explanation?
in non-network explanations the main focus is on: attributes of autonomous individual units, the associations among these attributes, and the usefulness of one or more attributes for predicting the level of another attribute social network analysis: refers to the set of actors and the ties among them views on characteristics of the social units arising out of structural or relational processes or focuses on properties of the relational system themselves inclusion of concepts and information on relationships among units in a study (Wasserman/Faust 2008: 6-9) 8

9 Which differences exist between a social network analysis and a non-network explanation?
the task is to understand properties of the social (economic or political) structural environment, and how these structural properties influence observed characteristics and associations among characteristics relational ties among actors are primary and attributes of actors are secondary each individual has ties to other individuals, each of whom in turn is tied to a few, some, or many others, and so on (Wasserman/Faust 2008: 6-9)

10 What is a Social Network?
A set of nodes (e.g., people, organisations, nation-states, etc.) A set of connections between nodes (e.g., friends, acquaintances, relatives) “consists of a finite set or sets of actors and the relation or relations defined on them. The presence of relational information is a critical and defining feature of a social network.” (Wasserman/Faust 2008:20) “A social network arises when all actors can, theoretically, have ties to all relevant actors” (Wasserman/Faust 2008:42) Shows how information is or can be communicated Shows how important are individual ‘nodes’ to the ability of the network to communicate Shows if there are key players in the network Shows if there are isolated parts of the network 10

11 Fundamental Concepts in Network Analysis
actor relational tie dyad triad subgroup group relation social network 11

12 Actor “discrete individual, corporate, or collective social units” (Wasserman/Faust 2008:17) Examples: people in a group, departments within in a corporation, public service agency in a city, nation-states in the world system Does not imply that they have volition or the ability to “act” 12

13 Relational tie Actors are linked to another by social ties
A tie “establishes a linkage between a pair of actors” Example of ties in SNA (Wasserman/Faust 2008:17): Evaluation of one person by another (expressed friendship, linking, or respect) Transfers of material resources (business transactions, lending or borrowing things) Association or affiliation (jointly attending a social event, or belonging to the same social club) Behavioral interaction (talking together, sending messages) Movement between places or statuses (migration, social or physical mobility) Physical connection (a road, river, or bridge connecting two points) Formal relations (authority) Biological relationships (kinship or descent) 13

14 Dyad a tie between two actors
“consists of a pair of actors and the (possible) tie(s) between them” (Wasserman/Faust 2008:18) Shows “properties of pairwise relationships, such as whether ties are reciprocated or not, or whether specific types of multiple relationships tend to occur together” (Wasserman/Faust 2008:18) 14

15 Triad “Triples of actors and associated ties” (Wasserman/Faust 2008:19) “a subset of three actors and the (possible) tie(s) among them” (Wasserman/Faust 2008:19) Triadic analyses focus on the fact whether the triad is Transitive : if actor i “likes” actor j, and actor j in turn “likes” actor k, then actor i will also “like” actor k Balanced: if actors i and j like each other, then i and j should be similar in their evaluation of a third actor, k, and i and j dislike each other, then they should differ in their evaluation of third actor, k 15

16 Subgroup Subgroup of actors is defined “as any subset of actors, and all ties among them” (Wasserman/Faust 2008:19) 16

17 Group “is the collection of all actors on which ties are to be measured” (Wasserman/Faust 2008:19) Actors in a group “belong together in a more or less bounded set (…) consists of a finite set of individuals on which network measurements are made” (Wasserman/Faust 2008:19) “The restriction to a finite set or sets of actors is an analytic requirement. Though one could conceive of ties extending among actors in a nearly infinite group of acts, one would have great difficulty analyzing data such a network. Modeling finite groups presents some of the more problematic issues in network analysis, including the specification of network boundaries, sampling, and the definition of group. Network sampling and boundary specification are important issues.” (Wasserman/Faust 2008:19f.) “however, in research applications we are usually forced to look at finite collections of actors and ties between them.” (Wasserman/Faust 2008:20) 17

18 Relation “the collection of ties of a specific kind among members of a group” (Wasserman/Faust 2008:20) Example: the set of friendship among pairs of children in a classroom For group of actors, several different relations might be measured “refers to the collection of ties of a given kind measured on pairs of actors from a specified actor set” (Wasserman/Faust 2008:20) Ties themselves only exist between specific pairs of actors 18

19 Work data sets What are network data?
Boundary specification and sampling Types of networks 19

20 What are network data? variables modes affiliation variables 20

21 Variables (Wasserman/Faust 2008:29) structural variables:
are measured on pairs of actors and are the cornerstone of social network data sets measure ties of a specific kind between pairs of actors example: business transaction between corporations, friendship between people, trade between nations composition variables: measurements of actor attributes (actor attribute variables) are of the standard social and behavioral science variety defined at the level of individual actors example: gender, race, ethnicity for people 21

22 Modes “the number of sets of entities on which structural variables are measured” (Wasserman/Faust 2008:35) One-mode network: all actors come from one set two-mode network: there are two set of actors: e.g. set consisting of corporations and another of non-profit organizations, contains measurements on which actors from one set have ties to actors from the other set higher-mode network: more set of entities: actors from different sets 22

23 Affiliation Variables
each affiliation variable is defined on a specific subset of actors a special type of two-mode network, but they only have one set of actors the second mode is a set of events: such as clubs or voluntary organizations to which the actor belong “events are defined not on pairs of actors, but on subsets of actors (…) often events are informal social occasions, such as parties or other gatherings, and observations or attendance or interactions among people provide the affiliation of the actors ” “subsets can be of any size” 23

24 Boundary specification and sampling I
What is your Population? (Wasserman/Faust 2008:31) Who are the relevant actors? Example: faculty in an academic department or corporations headquartered in a major metropolitan area: relatively easy to deal with But what to do in other cases if the boundary of the set of actors may be difficult if not impossible to determine “The boundary of a set of actors allows a researcher to describe and identify the population under study” Actor set boundaries are often based on the relative frequency of interaction, or intensity of ties among members as contrasted with non-members 24

25 Boundary specification and sampling II
Two different approaches to boundary specification in social network studies (cf. Laumann, Marsden, Prensk 1989) Realist approach: focuses on actor set boundaries and membership as perceived by the actors themselves (e.g. a street gang, members acknowledge as belonging to the gang) Nominalist approach: based on the theoretical concerns of the researcher (e.g. flow of computer messages among researchers in a scientific community; the list of actors might be the collection of people who published papers on the topic in the previous five years) In several applications, when the boundary is unknown, special sampling techniques such as snowball sampling and random nets (Wasserman/Faust 2008:32) 25

26 Boundary specification and sampling III: Sampling
sometimes it is not possible to take measurements on all actors in the relevant actor set (Wasserman/Faust 2008:33) is seen as “representative of the larger, theoretically interesting population (which must have a well-defined boundary and hence, a known size), and uses the sampled actors and data to make inferences about the population) example: snowball network sample (cf. Goodman 1961): “begins when the actors in a set of sample respondents report on the actors to whom they have ties of a specific kind” (Wasserman/Faust 2008:34) all of the nominated actors constitute the “first order “ zone of the network then all actors in this zone will be sampled and all the additional actors (those nominated by the actors in the “first order” zone who are not among the original respondents or those in this zone) are gathered these additional actors constitute the “second order” zone it is a chain method what means that several “order zones” can be defined 26

27 "Introduction in Social Network Analysis
"Introduction in Social Network Analysis. Theoretical Approaches and Empirical Analysis with computer-assisted programmes." II. meeting: Types of networks for SNA From organic solidarity (Durkheim) to information society and network society (Castells) Social capital 27

28 Social Network Analysis: Focus on interactions between individuals/ groups
Node: Any entity in a network (person, system, group, organization) Tie: Relationship/ interaction between two nodes. 28

29 Types of networks Network can be categorized by the nature of the sets of actors and the properties of the ties among them “The number of modes in a network refers to the number of distinct kinds of social entities in the network” (Wasserman/Faust 2008:35) One-mode networks: a single set of actors Two-mode networks: focus on two sets of actors, or one set of actors and one set of events 29

30 One-mode networks: a single set of actors (Wasserman/Faust 2008:36f.)
relations actor attributes 30

31 Actors in one-mode networks
can be a variety of types People Subgroups (consist of people Organizations Collectives / Aggregates: Communities (consists of subgroups of people), nation-states (larger entities, containing many organizations and subgroups) 31

32 Relations in one-mode networks
several kind of relations can be studied: (Wasserman/Faust 2008:37)  individual evaluations: friendship, linking, respect  “measurements of positive or negative affect of one person for another” transactions or transfer of material resources: lending or borrowing; buying or selling, contacts made by one actor of another in order to secure valuable resources, transfer of goods, exchange of gifts, social support ties transfer of non-material resources: communications, sending/receiving information  frequently communications between actors, where ties represent messages transmitted or information received 32

33 Relations in one-mode networks
interactions: “involve the physical interaction of actors or their presence in the same place at the same time” (Wasserman/Faust 2008:38), e.g. sitting next to each other, attending the same party, visiting a person’s home movement: physical (migration from place-to-place), social (movement between occupations or statuses) formal roles: e.g. dictated by power and authority in a management setting kinship: marriage, descent

34 Actor Attributes People can be queried about different features, like
age gender race socioeconomic status place of residence grade in school, etc. 34

35 Two Sets of Actors Relations measure ties between the actors in one set and actors in a second set Such networks are dyadic two-mode networks, “since these relations are functions of dyads in which the first actor and the second actor in the dyad are from different sets” (Wasserman/Faust 2008:39) 35

36 Source: courses. essex. ac
Source: %20Society%20as%20Network.ppt Sociology of networks beware – network analysis takes very distinct forms! sociometry Moreno (psychotherapy) graph theory White (mathematical sociology) social capital Bourdieu (social theory) ‘strength of weak ties’ Granovetter (new ec sociology) networks social exclusion Phillipson (social policy) network culture Terranova (cultural studies) network society Castells (social theory) 36

37 Source: courses. essex. ac
Source: %20Society%20as%20Network.ppt Social networks a way of representing social connections and social relationships, ie family, work, friends, political ties… number of ties? quality of ties? intensity of ties? content of ties? compare ‘network’ and ‘class’ as concepts? Sketch your own network… 37

38 Theories of the Information Society & Network Society

39 The Information Society
Definitions: “Post-industrial society in which information technology (IT) is transforming every aspect of cultural, political, and social life and which is based on the production and distribution of information. It is characterized by the (1) pervasive influence of IT on home, work, and recreational aspects of the individuals daily routine, (2) stratification into new classes—those who are information-rich and those who are information-poor, (3) loosening of the nation state's hold on the lives of individuals and the rise of highly sophisticated criminals who can steal identities and vast sums of money through information related (cyber) crime.” ( Societies that have become dependent upon complex electronic information networks and which allocate a major portion of their resources to information and communication activities” (Melody, 1990: 26-7) 39

40 Theoretical Foundations
“post-industrial society” (Daniel Bell 1973) Characteristics of the post-industrial society: Rise of the service sector Decline of agricultural sector Predominance of information-based work Knowledge as the key factor in the economy “information economy” (Machlup 1962, Porat 1977) 40

41 Webster´s Understanding of the Information Society
Technological Economic Occupational Spatial Cultural 41

42 Manuel Castells’ theory of The Network Society

43 43 43

44 What is a Network Society?
A new techno-economic system (society) key social structures and activities are organized around electronically processes information networks process of transformation to a network society started in the 1970s through the interaction of three main trends: IT revolution crisis of industrialism in both capitalist and statist societies profound cultural challenge and rise of social movements 44

45 Castell’s definition ”A network society is a society whose social structure is made of networks powered by microelectronics-based information and communication technologies.” ”Social structure: the org. arrangements of humans in relations of production, consumption, reproduction, experience and power expressed in meaningful communication coded by culture.” ”A network is a set of interconnected nodes. A network has no center, just nodes” Castells (2004) in The Network Society. A Cross-cultural perspective, (p. 3) 45

46 Castells, M. (1991), The Informational City
Castells, M. (1991), The Informational City. Information Technologies, Economic Restructuring, and the Urban-Regional Process, Oxford and Cambridge, Basil Blackwell network society is a social order embodying a logic like ‘space of flows’ space of flows is the material organization of time-sharing social practices that work through flows flows are purposeful, repetitive, programmable sequences of exchange and interaction between physically disjointed positions held by social actors in the economic, political, and symbolic structures of society presence and absence are critical sources of domination and change in our society 46 46

47 Castells, M. (1991), The Informational City
New information technologies are integrating the world in global networks of instrumentality In the new, informational mode of development the source of productivity lies in the technology of knowledge generation, information processing, and symbol communication the action of knowledge is the main source of productivity 47 47

48 network-theoretical considerations
Granovetter’s (1977) linkage of network morphology with action, by considering strong and weak network ties strong relations are multiplex and weak ones uniplex among strong relations: tendency of cluster formation linkage between different clusters can only occur by weak ties that form bridges Strength of Weak Ties is the ability to open up closed networks 48

49 On social capital “Social capital is defined by its function. It is not a single entity but a variety of different entities, with two elements in common: They all consist of some aspect of social structures, and they facilitate certain actions of actors - whether persons or corporate actors - within the structure. Like other forms of capital, social capital is productive, making possible the achievement of certain ends that in its absence would not be possible. Like physical capital and human capital, social capital is not completely fungible but may be specific to certain activities. A given form of social capital that is valuable in facilitating certain actions may be useless or even harmful for others. Unlike other forms of capital, social capital inheres in the structure of relations between actors and among actors. It is not lodged either in the actors themselves or in physical implements of production” (Coleman 1988: 98). 49

50 On social capital Putnam considers civic development in both North and South Italy South: vicious spiral of clientelism, patron-client relations and amoral familism, ‘force private violence and family provide a primitive substitute for civic community’ “Social trust, norms of reciprocity, networks of civic engagement, and successful cooperation are mutually reinforcing. Effective collaborative institutions require interpersonal skills and trust, but those skills and trust are also inculcated and reinforced by organized collaboration” (Putnam 1993: 180). 50

51 On social capital Fukuyama defines social capital as a given set of informal norms and values, which all members of a group share, and which facilitate cooperation between the group members ability and capacity to communicate in an uncomplicated way and to cooperate is ‘spontaneous solidarity’ which is an important part of social capital 51

52 "Introduction in Social Network Analysis
"Introduction in Social Network Analysis. Theoretical Approaches and Empirical Analysis with computer-assisted programmes." III. meeting: Sociometry Centrality, Brokerage, Prestige, Matrices, Density within social networks Introduction in the computer programme „Vennmaker“ Introduction in the computer programme „Pajek“ 52

53 Basic sociograms 53

54 Sociometry word sociometry comes from the Latin “socius,” meaning social and the Latin “metrum,” meaning measure a way of measuring the degree of relatedness among people a powerful tool for assessing dynamics and development in groups devoted to therapy or training Jacob Levy Moreno used sociometric techniques to assign residents to various residential cottages “Sociometry is that it is a methodology for tracking the energy vectors of interpersonal relationships in a group. It shows the patterns of how individuals associate with each other when acting as a group toward a specified end or goal” (Criswell 1960, p. 140). “the mathematical study of psychological properties of populations, the experimental technique of and the results obtained by application of quantitative methods” (Moreno, 1953, pp ) is based on the fact that people make choices in interpersonal relationships (Hoffman 2001)

55 55

56 Density actual number of connections in a network
expressed as a proportion of the total possible number of connections figure between 0 and 1 56

57 A simple relational matrix in which presence/absence of a relation is indicated by a 1 or 0 respectively: who drinks with whom? Tom Dick Sally Fred Alice 1 57

58 Note that in this case there is unnecessary repetition of information: if Tom drinks with Sally then Sally drinks with Tom Tom Sally 1 We need to be mindful of this in any calculations we may make. We have one relationship here, not two. 58

59 59

60 60

61 Centrality Important or prominent actors are those that are linked or involved with other actors extensively A person with extensive contacts (links) or communications with many other people central actor is one involved in many ties.

62 Betweenness Centrality
If two non-adjacent actors j and k want to interact and actor i is on the path between j and k, then i may have some control over the interactions between j and k Betweenness measures this control of i over other pairs of actors Thus, if i is on the paths of many such interactions, then i is an important actor.

63 Brokerage roles Sunbelt XXIV, Portorož, 2004 63 63

64 Prestige a more refined measure of prominence of an actor than centrality a prestigious actor is one who is object of extensive ties as a recipient Difference between centrality and prestige: centrality focuses on out-links prestige focuses on in-links

65 Programs for analysing networks : more than 50 We can only focus on few programs Egonet Visone Vennmaker Pajek Ucinet

66 Egonet is a program for the collection and analysis of egocentric network data is designed to allow the researcher to enter the questions they wish to ask, and output, among other things a data set where the unit of analysis is the respondent It is also designed to generate an adjacency matrix for each respondent

67 Visone visone is a long-term research project, in which models and algorithms to integrate and advance the analysis and visualization of social networks are being developed important part of visone is the design and implementation of a software tool intended for research and teaching in social network analysis designed to allow experts and novices alike to apply innovative and advanced visual methods with ease and accuracy

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