The Netherlands CLIQUES , CLUBS AND CLANS

In the analysis of social networks adequate concepts are necessary to indicate various types and configurations of social groups such as peer groups, coteries, acquaintance groups, etc. The problem has theoretically been argued convincingly by e.g. Kadushin (1968), who introduced the general concept of "social circle". In the actual empirical study of social networks there is therefore a need for adequate operational and analytically useful concepts to represent such more or less closely knit groups. Many of these can be developed with the help of the theory of graphs and networks. A well-known concept, more or less corresponding to that of the peer group is the clique: a group all members of which are in contact with each other or are friends, know each other, etc. However, similar concepts will be necessary to denote less closely knit, yet significantly homogeneous social groups, such as "acquaintance groups", where every pair of members, if they are not in mutual contact, have mutual acquaintances, or common third contacts, etc. In this latter type of social group an important aspect is brought out by the question of whether the homogeneity of a social group is due to its position in a larger social network in which it is embedded, or whether it is a property of the group itself as a more or less autarchic unit, independent of the surrounding social network. In the first case, for instance, a group may be as closely knit as an "acquaintance network",