  The analysis of bibliometric networks, such as co-authorship, bibliographic
coupling, and co-citation networks, has received a considerable amount of
attention. Much less attention has been paid to the construction of these
networks. We point out that different approaches can be taken to construct a
bibliometric network. Normally the full counting approach is used, but we
propose an alternative fractional counting approach. The basic idea of the
fractional counting approach is that each action, such as co-authoring or
citing a publication, should have equal weight, regardless of for instance the
number of authors, citations, or references of a publication. We present two
empirical analyses in which the full and fractional counting approaches yield
very different results. These analyses deal with co-authorship networks of
universities and bibliographic coupling networks of journals. Based on
theoretical considerations and on the empirical analyses, we conclude that for
many purposes the fractional counting approach is preferable over the full
counting one.
