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1 – 10 of over 3000The Bradford law is explored theoretically by means of a very mixed Poisson model which, it is claimed, elucidates the uncertainties surrounding the law and its applications. It…
Abstract
The Bradford law is explored theoretically by means of a very mixed Poisson model which, it is claimed, elucidates the uncertainties surrounding the law and its applications. It is argued that Bradford succeeded in formulating an empirical regularity which has pure and hybrid forms but that all the variants can be subsumed under a simple logarithmic law which, for reasons explained, escapes exact expression in conventional frequency terms. The theoretical aspects discussed include the hybridity of form, estimations, sampling problems, the stability of ranks, homogeneity of data, and tests of significance. Some numerical examples, some simulated and some drawn from social contexts outside bibliography, are used both to illustrate theoretical issues and also to indicate the wide generality of the Bradford law. Possible applications and developments of the theory are indicated.
Haitun has recently shown that empirical distributions are of two types—‘Gaussian’ and ‘Zipfian’—characterized by the presence or absence of moments. Gaussian‐type distributions…
Abstract
Haitun has recently shown that empirical distributions are of two types—‘Gaussian’ and ‘Zipfian’—characterized by the presence or absence of moments. Gaussian‐type distributions arise only in physical contexts: Zipfian only in social contexts. As the whole of modern statistical theory is based on Gaussian distributions, Haitun thus shows that its application to social statistics, including cognitive statistics, is ‘inadmissible’. A new statistical theory based on ‘Zipfian’ distributions is therefore needed for the social sciences. Laplace's notorious ‘law of succession’, which has evaded derivation by classical probability theory, is shown to be the ‘Zipfian’ frequency analogue of the Bradford law. It is argued that these two laws together provide the most convenient analytical instruments for the exploration of social science data. Some implications of these findings for the quantitative analysis of information systems are briefly discussed.
Cristina Faba-Pérez and Ana-María Cordero-González
– The purpose of this paper was to check the validity of Bradford’s Law in the contemporary world of academic electronic mailing lists.
Abstract
Purpose
The purpose of this paper was to check the validity of Bradford’s Law in the contemporary world of academic electronic mailing lists.
Design/methodology/approach
The present research study applied Bradford’s Law to academic electronic mailing lists to determine: whether, on the Internet, mailing lists and the posts sent to them follow the same distribution as scientific journals and the articles published in them with respect to the original form of Bradford’s Law; and whether the behaviour of the Bradford distributions differs depending on the type of academic discipline (social studies or sciences) and subject category (documentation and education, medicine and life sciences) to which the list belongs. As a prior step, the utility of mailing lists was analysed during the 10-year period of 2002-2011, together with their expected future in terms of ratifying the applicability of the Law.
Findings
The results showed that, in general, electronic mailing lists are continuing to be used, and that Bradford’s Law is indeed satisfied, especially in the science subject categories, coherent with the fact that Bradford’s Law in cybermetrics holds only for fairly narrow (closed) and well-defined (homogeneous) environments.
Originality/value
The originality of the present research study was to check the validity of the historic Bradford’s Law in the contemporary world of Internet.
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Jeppe Nicolaisen and Birger Hjørland
The purpose of this research is to examine the practical potentials of Bradford's law in relation to core‐journal identification.
Abstract
Purpose
The purpose of this research is to examine the practical potentials of Bradford's law in relation to core‐journal identification.
Design/methodology/approach
Literature studies and empirical tests (Bradford analyses).
Findings
Literature studies reveal that the concept of “subject” has never been explicitly addressed in relation to Bradford's law. The results of two empirical tests (Bradford analyses) demonstrate that different operationalizations of the concept of “subject” produce quite different lists of core‐journals. Further, an empirical test reveals that Bradford analyses function discriminatorily against minority views.
Practical implications
Bradford analysis can no longer be regarded as an objective and neutral method. The received view on Bradford's law needs to be revised.
Originality/value
The paper questions one of the old dogmas of the field.
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In this paper we start from the well‐known fact that from the law of Lotka
Any statistical regularities found in documentation should be fully exploited to produce estimates or predictions and to save documentalists work. But present formulations of the…
Abstract
Any statistical regularities found in documentation should be fully exploited to produce estimates or predictions and to save documentalists work. But present formulations of the Bradford distribution demand penetrating search for peripheral papers and tedious computation in application. The present paper shows that the Bradford distribution is closely related to the Zipf distribution. It requires data on only the most productive journals, is mathematically simple and amenable to graphical methods if a proposed idea of the ‘completeness’ of a search is accepted. For comparability of results, certain conditions, which include a specified minimum level of productivity of journals, need to be standardized. A standard form is suggested. It is found, however, that a modified form of the Bradford distribution is required when Bradford‐type collections of journals are merged into larger collections, when ‘saturation’ of the most productive journals occurs.
The purpose of this paper is to develop a standard procedure for Bradford analysis: export citations from research databases to a bibliographic management tool, separate the…
Abstract
Purpose
The purpose of this paper is to develop a standard procedure for Bradford analysis: export citations from research databases to a bibliographic management tool, separate the desired citation fields with bibliographic output styles, and then manipulate the empirical data, formulate graph and analyze linearity with Microsoft Excel.
Design/methodology/approach
The methodology mainly employed by the paper is to test the theory of Bradford's law of scattering. Based on research work and experiments, a standard procedure for Bradford analysis is to be developed.
Findings
A standard procedure for Bradford analysis is developed. The study also shows that the literature in systems librarianship follows Bradford distribution.
Originality/value
Many fields or disciplines of literature have been found to follow Bradford's law, which seems to offer a great potential promise for solving library problems. However, empirical Bradford analysis demands tedious computation, and sophisticated graphical formulation. This paper develops an easy operational procedure for Bradford analysis, which will shed light on problem solving in a similar bibliometric analysis.
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An exact, discrete formulation of Bradford's law describing the distribution of articles in journals is derived by showing that Bradford's law is a special case of the…
Abstract
An exact, discrete formulation of Bradford's law describing the distribution of articles in journals is derived by showing that Bradford's law is a special case of the Zipf‐Mandelbrot ‘rank frequency’ law. A relatively simple method is presented for fitting the model to empirical data and estimating the number of journals and articles in a subject collection. This method is demonstrated with an example application.
A probabilistic mechanism is proposed to describe various forms of the Bradford phenomenon reported in bibliometric research. This leads to a stochastic process termed the Waring…
Abstract
A probabilistic mechanism is proposed to describe various forms of the Bradford phenomenon reported in bibliometric research. This leads to a stochastic process termed the Waring process, a special case of which seems to conform with the general features of ‘Bradford's Law’. The presence of a time parameter in the model emphasises that we are considering dynamic systems and allows the possibility of predictions being made.
Bradford distributions describe the relationship between ‘journal productivities’ and ‘journal rankings by productivity’. However, different ranking conventions exist, implying…
Abstract
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.
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