Bradford ranking conventions and their application to a growing literature

Abstract

If you would like to write for this, or any other Emerald publication, then please use our Emerald for Authors service information about how to choose which publication to write for and submission guidelines are available for all. Please visit www.emeraldinsight.com/authors for more information. About Emerald www.emeraldinsight.comEmerald is a global publisher linking research and practice to the benefit of society. The company manages a portfolio of more than 290 journals and over 2,350 books and book series volumes, as well as providing an extensive range of online products and additional customer resources and services.Emerald is both COUNTER 4 and TRANSFER compliant. The organization is a partner of the Committee on Publication Ethics (COPE) and also works with Portico and the LOCKSS initiative for digital archive preservation.Bradford distributions describe the relationship between 'journal productivities' and 'journal rankings by productivity'. However, different ranking conventions exist, implying some ambiguity as to what the Bradford distribution 'is'. A need accordingly arises for a standard ranking convention to assist comparisons between empirical data, and also comparisons between empirical data and theoretical models. Five ranking conventions are described including the one used originally by Bradford, along with suggested distinctions between 'Bradford data set', 'Bradford distribution', 'Bradford graph', 'Bradford log graph', 'Bradford model' and 'Bradford's Law'. Constructions such as the Lotka distribution, Groos droop (generalised to accommodate growth as well as fall-off in the Bradford log graph), Brookes hooks, and the slope and intercept of the Bradford log graph are clarified on this basis. Concepts or procedures questioned include: (1) 'core journal', from the Bradfordian viewpoint; (2) the use of traditional statistical inferential procedures applied to Bradford data; and (3) R(n) as a maximum (rather than median or mean) value at tied-rank values.The framework established is selectively illustrated in regard to a growing humanities literature, where particular attention was paid to generating a self-consistent and complete Bradford data set. No significant Groos effects were apparent, lending confirmation to the 'Law' as originally expressed by Bradford. Other empirical conclusions drawn are: (1) Brookes's parameter 's' is unsatisfactory as a measure of subject breadth and appears instead to reflect the size of the document corpus on a given subject, an alternative measure of subject breadth being suggested; (2) a terminal Brookes 'hook' for describing journals that (temporarily) produce zero articles provides a theoretically meaningful, although arbitrarily conditioned, extension to the Bradford graph; (3) the Lotka model of the related journal frequency distribution, which is unaffected by choice of rank convention, is more accurate than a logarithmic model of that distribution; and (4) the randomness underlying article production processes determines significant variations in journal...

Does Bradford's Law of Scattering predict the size of the literature in Cochrane Reviews?

“…When journals were tied in terms of articles published, they were ranked according to convention ''C1'' in Heine (1998) [4]. This convention gives journals that produce the same number of articles an arbitrary and sequential rank from the previously ranked journal, rather than assigning all the journals the same rank.…”

“…The middle third (Zone 2) includes the journals that have had an average amount of citations, and the bottom third (Zone 3 or tail) comprises the long tail of journals that are seldom cited and regarded as of marginal importance to the subject [2]. Researchers have defined a subject area in lexical, semantic, and subject scattering terms [3], and some argue that problems in defining ''subject'' may not matter, provided it is applied consistently [4].…”

Bradford's Law and its relevance to researchers

“…Such scepticism adds weight to Urquhart's claim that librarianship cannot be viewed as "an exact science" and that laws within the discipline do not deal in absolutes [1, p. 83]. In addition, as Heine recognises, there is a significant lack of standardisation in investigations relating to Bradford's Law; he highlights a range of semantic ambiguities in the inherent concepts and variations in mathematical practices that may be applied in work in this area [17].…”

“…"Journals", in this sense, was defined as including annuals such as Advances in Librarianship and the Annual Review of Information Science and Technology but proceedings of yearly conferences were ignored as they were believed to constitute a separate entity. Since the interpretation of the concept of "journal" is so fundamental to work involving Bradford's Law, it is, as Heine comments, surprising that this issue has attracted little discussion in the literature [17], and, in the absence of useful guidance from elsewhere, the researcher had no alternative but to make his own ruling. Shenton's records of the citations have been revisited for this paper in order to explore the value of Bradford's Law to describe, in statistical terms, the distribution, within the journals, of the papers cited.…”

Practical potentials of Bradford's law: a critical examination of the received view

“…The same is not generally true either of the social sciences or of the humanities. However, Bradford's law has been examined in both the social sciences and the humanities (e.g., Donohue, 1972;Heine, 1998;von Ungern-Sternberg, 2000;Yeon-Kyoung, 1994). Bradford's law in relation to questions concerning theoretical frameworks accepted by the majority has, as far as we know, never been examined or discussed.…”