Compare methods

	Relative Specialization / Activity Index	Garfield's Law of Concentration
Field	Bibliometrics	Bibliometrics
Family	Process / pipeline	Process / pipeline
Year of origin	1986	1972
Originator	J. Davidson Frame (activity index); András Schubert & Tibor Braun (relative indicators)	Eugene Garfield
Type	Normalized bibliometric indicator of revealed research specialization	Descriptive bibliometric law and core-journal identification pipeline
Seminal source	Schubert, A., & Braun, T. (1986). Relative indicators and relational charts for comparative assessment of publication output and citation impact. Scientometrics, 9(5-6), 281-291.	Garfield, E. (1972). Citation analysis as a tool in journal evaluation. Science, 178(4060), 471-479.
Aliases	Activity Index, Relative Specialization Index, Revealed Comparative Advantage in Science, Attractivity Index	Law of Concentration, Core Journal Concentration, Garfield Concentration Law
Related	3	3
Summary	The Relative Specialization Index and the closely related Activity Index measure how much a country, institution, or other unit concentrates its research effort in a given field relative to a global benchmark. The Activity Index, popularized by J. Davidson Frame in the 1970s, compares a unit's share of its own output devoted to a field against the world's share of output in that field: a value above 1 means the unit is more active (more specialized) in that field than the world average, and below 1 means less. András Schubert and Tibor Braun's relative-indicator framework formalized this family and introduced bounded, symmetric variants and 'relational charts' that pair publication activity with citation 'attractivity'. These indices are the scientometric analogue of revealed comparative advantage in trade and are central to national and institutional research-profiling.	Garfield's Law of Concentration is the bibliometric principle that the bulk of the significant scientific literature is concentrated in a relatively small, largely multidisciplinary core of journals. Formulated by Eugene Garfield — founder of the Science Citation Index — and presented in his 1972 Science paper 'Citation analysis as a tool in journal evaluation', the law observes that when journals are ranked by how often they are cited, a core of perhaps 500 to 1,000 journals accounts for the overwhelming majority of all citations across all fields. Garfield framed it as a generalization and corollary of Bradford's earlier law of scattering: the long tail of any one discipline's literature is in large part composed of the cores of other disciplines, so a single multidisciplinary core covers science as a whole. The law underpins the rationale for selective, citation-based journal indexing.