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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...