Diese Datenbank enthält über 40.000 Dokumente zu Themen aus den Bereichen Formalerschließung – Inhaltserschließung – Information Retrieval.
© 2015 W. Gödert, TH Köln, Institut für Informationswissenschaft / Powered by litecat, BIS Oldenburg (Stand: 28. April 2022)
1Egghe, L. ; Liang, L. ; Rousseau, R.: ¬A relation between h-index and impact factor in the power-law model.
In: Journal of the American Society for Information Science and Technology. 60(2009) no.11, S.2362-2365.
Abstract: Using a power-law model, the two best-known topics in citation analysis, namely the impact factor and the Hirsch index, are unified into one relation (not a function). The validity of our model is, at least in a qualitative way, confirmed by real data.
2Wei, J. ; Zhao, D. ; Liang, L.: Estimating the growth models of news stories on disasters.
In: Journal of the American Society for Information Science and Technology. 60(2009) no.9, S.1741-1755.
Abstract: Understanding the growth models of news stories on disasters is a key issue for efficient disaster management. This article proposes a method to identify three growth models: the Damped Exponential Model, the Normal Model, and the Fluctuating Model. This method is proven to be valid using the 112 disasters occurring between 2003 and 2008. The factors that influence the likelihood of the growth models include disaster types, newsworthy material, disaster severity, and economic development of the affected area. This article suggests that disaster decision-makers can identify the respective likelihood of the three growth models of news stories when a disaster happens, and thereby implement effective measures in response to the disaster situation.
3Liang, L. ; Rousseau, R.: Yield sequences as journal attractivity indicators : "payback times" for Science and Nature.
In: Journal of documentation. 64(2008) no.2, S.229-245.
Abstract: Purpose - The yield period of a journal is defined as the time needed to accumulate the same number of citations as the number of references included during the period of study. Yield sequences are proposed as journal attractivity indicators describing dynamic characteristics of a journal. This paper aims to investigate their use. Design/methodology/approach - As a case study the yield sequences of the journals Nature and Science from 1955 onward are determined. Similarities and dissimilarities between these sequences are discussed and factors affecting yield periods are determined. Findings - The study finds that yield sequences make dynamic aspects of a journal visible, as reflected through citations. Exceptional circumstances (here the publication of Laemmli's paper in 1970 in the journal Nature) become clearly visible. The average number of references per article, the citation distribution and the size of the database used to collect citations are factors influencing yield sequences. Originality/value - A new dynamic indicator for the study of journals is introduced.
Objekt: Science ; Nature
4Egghe, L. ; Liang, L. ; Rousseau, R.: Fundamental properties of rhythm sequences.
In: Journal of the American Society for Information Science and Technology. 59(2008) no.9, S.1469-1478.
Abstract: Fundamental mathematical properties of rhythm sequences are studied. In particular, a set of three axioms for valid rhythm indicators is proposed, and it is shown that the R-indicator satisfies only two out of three but that the R-indicator satisfies all three. This fills a critical, logical gap in the study of these indicator sequences. Matrices leading to a constant R-sequence are called baseline matrices. They are characterized as matrices with constant w-year diachronous impact factors. The relation with classical impact factors is clarified. Using regression analysis matrices with a rhythm sequence that is on average equal to 1 (smaller than 1, larger than 1) are characterized.
5Liang, L.: R-Sequences : relative indicators for the rhythm of science.
In: Journal of the American Society for Information Science and Technology. 56(2005) no.10, S.1045-1049.
Abstract: Like most activities in the world, scientific evolution has its own rhythm. How can this evolutionary rhythm be described and made visible? Do different fields have different rhythms, and how can they be measured? In order to answer these questions a relative indicator, called R-sequence, was designed. This indicator is time dependent, derived from publication and citation data, but independent of the absolute number of publications, as weIl as the absolute number of citations, and can therefore be used in a comparison of different scientific fields, nations, Institutes, or journals. Two caiculation methods of the R-sequence-the triangle method and the parallelogram method-are introduced. As a case study JASIS(T)'s R-sequence has been obtained.