This chapter illustrates some issues which can be defined as coming under ‘the social networks’ approach, which is composed of both a general paradigm (Degenne, 1983; Degenne and Forsé, 1994; Ferrand and Snijders, 1997; Wellman and Berkowitz, 1988) and various kinds of methodologies (Wasserman and Faust, 1994; Marsden, 1990). In this approach, individuals are seen as actors who behave intentionally and try to manage the gap between desires and prohibitions, goals and resources. Their relations, and the networks they form, are effects and conditions of actions—effects when actors bargain to create or transform relations, conditions when relations provide resources and alternatives, or impose constraints on actions. Then existing relations influence some emerging or other existing relations. Another way of saying this is that some kinds of relations—not all—are interdependent or form ‘systems’.
Sometimes researchers can describe a whole network, that is, all relations of a given kind amongst a given set of people: pupils in a classroom, subset of a local elite, and so on. But such a methodology is often limited to the deep structural description of limited milieus. Sexual research on large populations uses questionnaires administered to randomly selected, a priori unconnected people. The methodology forbids direct description of the whole network, but allows the statistical description of ‘personal networks’ in given populations. In mass surveys it is possible to ask interviewees to describe some personal relationships as elements of their environments. Data provided by such surveys can then be used to define simulation models’ parameters of comprehensive sexual networks (Kretzschmar et al., 1994).
Sex surveys ask individuals to describe some—two, three, more recent—sexual relationships. It is possible to conceptualize sexual links as interdependent if they are reciprocally conditioned, for example, when an existing primary