Social Networks 165
important to know the following basic differentiations concerning scope and
methodology made within social network analysis.
A structural analysis can be performed for either a global or an ego-
centered network.10 For complete or global networks, an excellent source
material would be needed—a source or sources that would reveal all extant
informal relationships. Criteria for differentiating between members of the
network and non-members would have to be defined as well. Even in appli-
cation to modern networks, neither the source problem nor the problem of
membership definition can be solved satisfactorily. Instead, often ego-centered
networks are analyzed. Such ego-centered or personal networks comprise the
set of relationships a certain person has. This seems to be a reasonable method
to approach the Hanseatic commercial exchange networks.
Networks can also be reconstructed on the empirical basis of either a single
type of relationship or multiple sorts of personal connections.11 A network
that is based only on one type of relationship is called a one-mode network.
However, when a person has many relations, it is called a two-mode or multi-
mode network. Both approaches can describe historical, informal social struc-
tures. One example of a one-mode network is the common membership of
people in the Hanseatic towns’ official societies or fraternities (see below).
Kinship and commercial exchange relations, for instance, would make a two-
mode network out of it. Two-mode networks are “real” networks because sev-
eral distinct layers of social structure are interwoven in them.
Finally, closeness within a social network can vary depending on whether
the measurement of closeness is relation-based or position-based.12 In a
relation-based approach, closeness of network members is thought of as cohe-
siveness. Individuals are close to each other because they are located near to
each other within the network and because they do have intensive personal
contact. This method can be used for identifying and describing Hanseatic
social networks as far as opportunities to get in contact, either personally or by
letter, can be analyzed. In contrast, with a position-based approach, people are
connected through structurally equivalent positions within a social network,
not by personal contact. Hence, closeness is not a result of personal relation-
ship; it stems exclusively from structural equivalence. By this approach social
roles are identified, but it also goes beyond the original idea of a social net-
work being based on social contact. The position-based approach could be
10 Trezzini, “Konzepte und Methoden” (see footnote 6), 380.
11 Trezzini, “Konzepte und Methoden” (see footnote 6), 379f.
12 Trezzini, “Konzepte und Methoden” (see footnote 6), 382f.; Kappelhoff, “Cliquenanalyse”
(see footnote 7), 39–41.