  The purpose of this paper is to describe the evaluation of the effectiveness
of the bibliometric technique Bradfordizing in an information retrieval (IR)
scenario. Bradfordizing is used to re-rank topical document sets from
conventional abstracting & indexing (A&I) databases into core and more
peripheral document zones. Bradfordized lists of journal articles and
monographs will be tested in a controlled scenario consisting of different A&I
databases from social and political sciences, economics, psychology and medical
science, 164 standardized IR topics and intellectual assessments of the listed
documents. Does Bradfordizing improve the ratio of relevant documents in the
first third (core) compared to the second and last third (zone 2 and zone 3,
respectively)? The IR tests show that relevance distributions after re-ranking
improve at a significant level if documents in the core are compared with
documents in the succeeding zones. After Bradfordizing of document pools, the
core has a significant better average precision than zone 2, zone 3 and
baseline. This paper should be seen as an argument in favour of alternative
non-textual (bibliometric) re-ranking methods which can be simply applied in
text-based retrieval systems and in particular in A&I databases.
