THE BRADFORD DISTRIBUTION
| Published date | 01 March 1967 |
| Date | 01 March 1967 |
| DOI | https://doi.org/10.1108/eb026430 |
| Pages | 197-207 |
| Author | FERDINAND F. LEIMKUHLER |
| Subject Matter | Information & knowledge management,Library & information science |
THE BRADFORD DISTRIBUTION
FERDINAND F. LEIMKUHLER
Professor
of Industrial Engineering, Purdue University,
Lafayette, Indiana
The distribution of references in
a
collection of pertinent source documents
can be described and predicted by the relation
where the parameter β is related to the subject field and the completeness
of the collection. The model is used to predict the reference yield of
ab-
stracting journals in a search for thermophysical property data. It is used
also to explain differences among various literature studies of the past in
terms of differences in subject and comprehensiveness of search. The
model
is
derived from S. C. Bradford's 'law of scattering' and
is
called the
Bradford Distribution.
INTRODUCTION
THE CURRENT REVOLUTION in computer-aided, micro-analytic
techniques of information retrieval was largely justified by earlier studies
of the literature used in scientific research. These studies showed that re-
searcher interest was widely scattered among formal titles and classifica-
tions and much more extensive than the coverage provided by existing
bibliographic services. The most important measure of scatter used in em-
pirical studies
is
'title dispersion' which
is
defined
as
the degree to which the
useful literature of
a
given subject area is scattered through a number of
different books and journals. Stevens3 made a comparative analysis of title
dispersion data from eight studies
as
shown in Table
1.
By inspection of this
data, he concluded that the dispersion is smaller in pure science, greater in
technology, and greatest in the humanities.
Of particular interest
is
the work of S. C. Bradford.1 He studied the title
dispersion of useful papers in two
areas:
applied geophysics and lubrication,
by arranging the source titles in order of productivity and then dividing
them into three approximately equal groups
as
shown in Table
2.
Bradford
concluded that the
ratios
of the
titles in
successive
zones
followed
a
common
pattern, and proposed the following 'law of scattering':
If scientific journals are arranged in order of decreasing productivity of
articles on a given subject, they may be divided into a nucleus of
perio-
dicals more particularly devoted to the subject, and several groups or
zones containing the same number of articles as the nucleus, where the
197
To continue reading
Request your trial