by deWnition it reXects only ego’s network. Alternatively, acomplete networkprovides
a more comprehensive perspective. Data for a complete network are collected byWrst
identifying a group of actors and then collecting information on relationships
between all of them. Such data can be diYcult to collect for two reasons. First,
identifying connections between all the actors in a network creates a large volume of
data for even a small number of actors. Second, complete networks confront a
problem of boundary speciWcation. As the small world phenomenon demonstrates,
everyone may be (at several removes) connected to everyone else. So where should
the boundary be drawn? Network analysts generally solve this problem in one of two
ways—each of which corresponds to a diVerent technique for gathering the data.
One approach is to specify the boundary at the outset on the basis of non-network
criteria—for example the boundary of the organization or work unit, the policy
sector, or geographical units. In such cases, it is often useful to begin with a complete
list of the individuals, groups, or organizations contained within this boundary. The
researcher then asks each actor on the list about their relationship with every other
actor on the list. A second approach is often used when the boundary is diYcult
to specify ahead of time. In fact, identiWcation of who is part of the network may be
one of the main purposes for gathering data. In this case, snowball sampling is used
to collect network data. Much like egocentric data, this approach starts with a
few focal actors and then asks them about their relationships. It then builds
outward, asking actors speciWed in theWrst round of interviewing who they are
related to. Sampling may continue until the discovery of new actors drops oV.
4PolicyNetworks
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The network analysis literature described above has mostly been developed in
sociology and anthropology. In political science, a largely separate body of research
has developed to study ‘‘policy networks.’’ The policy network literature itself arose
at the conXuence of several streams of research. Among the earliest precursors to
the policy network literature was Heclo and Wildavsky’s ( 1974 ) study of the British
Treasury Department, which uncovered the importance of personal networks
between civil servants and politicians as an important factor shaping policy
decisions. In the USA, development of the policy network concept arose out of
work on ‘‘sub-governments’’—the idea that policy-making and implementation
were controlled by a select group of agencies, legislators, and interest groups.
Working in this tradition, Heclo ( 1978 ) coined the term ‘‘issue network’’ to describe
more diVuse forms of linkage than implied by the terms ‘‘sub-government’’ or
80 christopher ansell