Bradford's Law

Bradford's Law is a statistical law discovered by Samuel C. Bradford in 1934 in the field of bibliometrics . It describes the distribution of articles on a specific topic among various specialist journals or periodicals that actually do not deal with this topic or do not deal directly with it. This law and the studies on which it is based were published in the journal Engineering in 1934 .

description

Bradford's motivation was the large number of specialist journals and similar weekly media on specific subject areas and the associated high costs for regular procurement and archiving for libraries and similar institutions.

Bradford was particularly keen to highlight the "loss" of information when there is only a limited amount of specialist journals, known as "core journals" that are specifically related to a particular topic.

A selection of magazines is divided into zones on a specific topic. The first zone is the core; here you will find those journals that specifically deal with the selected subject area. The following zones contain magazines with a different focus, but which still contain articles on the subject.

According to Bradford's law, the same number of articles on a given topic are found in groups of , etc. different journals. The parameter corresponds to the ratio of the number of magazines between two consecutive zones. Bradford's Law provides for the distribution of articles on a focus topic in core journals, related journals, and remaining journals. Bradford concluded that limiting only to core journals meant about 2/3 information loss. ${\ displaystyle n ^ {1}}$ ${\ displaystyle n ^ {2}}$ ${\ displaystyle n}$

The law was formulated mathematically in 1948 by Brian C. Vickery (1918-2009) under the name Bradford's Law of Scattering and is a power law that can also be transferred to other areas, such as websites and social systems . A simplified variant of a comparable distribution is known as the 80/20 rule .

Examples

For example, if there are 4 core journals in a subject area that publish 10 relevant articles in a certain period and 10 additional articles are in 12 other journals during the same period, then the factor for the subject area is . For 10 further relevant articles, n times more journals have to be searched, i.e. 4, 12, 36, 108 ... In addition, it can happen that further relevant articles are available, but with a strongly decreasing probability. ${\ displaystyle n = 12/4 = 3}$

Bradford made his law after examining a bibliography on geophysics with a total of 326 journals. He found that 9 journals contained 429 articles, 59 had 499 articles, and the remaining 258 had 404 articles.

application

Bradford's law can roughly be used to determine the point at which it makes sense to start a new magazine for a particular subject (around half of all start-ups do not exist). To be successful with a new core journal, the total number of articles published must grow at least in accordance with Bradford's law.

The law can also be used to plan magazine purchases in libraries and the effort required for research ( Bradfordizing ). It follows from Bradford's law that one should not limit oneself to the core journals when searching for literature, but should do extensive research. The rule thus confirms the principle that all scientific disciplines are interrelated. The success of general journals such as Science and Nature can be explained by interdisciplinarity .

literature

Ursula Lelle, Michaela Lambach, Barbara Kremmling: Samuel Clement Bradford and his “Law of Scattering” . Frankfurt am Main: Society for Information and Documentation mbH, 1984. An introductory presentation with a selection bibliography.
BC Brookes : "Sources of information on specific subjects" by SC Bradford . In: Journal of Information Science, Vol. 10 (1985) pp. 173-175 (introduction to reprinting of SC Bradford's 1934 paper).
Stefan Hauff: Bradford's Law . Term paper at the FH Potsdam, 1999 ( PDF )
Hjørland, Birger: Scattering. In: Core Concepts in Library and Information Science: [1]
Hjørland, Birger; Nicolaisen, Jeppe (2005): Bradford's Law of Scattering: Ambiguities in the Concept of "Subject". In: F. Crestani and I. Ruthven (Eds.): CoLIS 2005, LNCS 3507, pp. 96 - 106, 2005. ( full text with PDF link )
on this: Umstätter, Walther (2005): Notes on Birger Hjørland and Jeppe Nicolaisen: Bradford's Law of Scattering: Ambiguities in the Concept of "Subject". In: LIBREAS - Library Ideas 3/2005 full text

Web links

FH Potsdam: Bradford's Law (PDF file; 83 kB)

swell

^ Samuel Bradford: Sources of Information on Specific Subjects . In: Engineering. 137: 85-86 (1934); Reprinted in: Journal of Information Science. Vol. 10 (1985) pp. 176-180.
^ Brian C. Vickery: Bradford's Law of Scattering . In: Journal of Documentation 4, 1948, pp. 198-203.

[1] Samuel Bradford: Sources of Information on Specific Subjects . In: Engineering. 137: 85-86 (1934); Reprinted in: Journal of Information Science. Vol. 10 (1985) pp. 176-180.

[2] Brian C. Vickery: Bradford's Law of Scattering . In: Journal of Documentation 4, 1948, pp. 198-203.