  A survey can be represented by a bipartite network as it has two types of
nodes, participants and items in which participants can only interact with
items. We introduce an agreement threshold to take a minimal projection of the
participants linked by shared responses in order to identify opinion-based
groups. We show that in American National Election Studies-data, this can
identify polarisation along political attitudes. We also take a projection of
attitudes that are linked by how participants respond to them. This can be used
to show which attitudes are commonly held together in different countries or
communities.
