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)
41Rousseau, R. ; Zuccala, A.: ¬A classification of author co-citations : definitions and search strategies.
In: Journal of the American Society for Information Science and Technology. 55(2004) no.6, S.513-529.
Abstract: The term author co-citation is defined and classified according to four distinct forms: the pure first-author co-citation, the pure author co-citation, the general author co-citation, and the special co-authorlco-citation. Each form can be used to obtain one count in an author co-citation study, based an a binary counting rule, which either recognizes the co-citedness of two authors in a given reference list (1) or does not (0). Most studies using author co-citations have relied solely an first-author cocitation counts as evidence of an author's oeuvre or body of work contributed to a research field. In this article, we argue that an author's contribution to a selected field of study should not be limited, but should be based an his/her complete list of publications, regardless of author ranking. We discuss the implications associated with using each co-citation form and show where simple first-author co-citations fit within our classification scheme. Examples are given to substantiate each author co-citation form defined in our classification, including a set of sample Dialog(TM) searches using references extracted from the SciSearch database.
Themenfeld: Citation indexing ; Informetrie
42Egghe, L. ; Rousseau, R.: ¬A measure for the cohesion of weighted networks.
In: Journal of the American Society for Information Science and technology. 54(2003) no.3, S.193-202.
Abstract: Measurement of the degree of interconnectedness in graph like networks of hyperlinks or citations can indicate the existence of research fields and assist in comparative evaluation of research efforts. In this issue we begin with Egghe and Rousseau who review compactness measures and investigate the compactness of a network as a weighted graph with dissimilarity values characterizing the arcs between nodes. They make use of a generalization of the Botofogo, Rivlin, Shneiderman, (BRS) compaction measure which treats the distance between unreachable nodes not as infinity but rather as the number of nodes in the network. The dissimilarity values are determined by summing the reciprocals of the weights of the arcs in the shortest chain between two nodes where no weight is smaller than one. The BRS measure is then the maximum value for the sum of the dissimilarity measures less the actual sum divided by the difference between the maximum and minimum. The Wiener index, the sum of all elements in the dissimilarity matrix divided by two, is then computed for Small's particle physics co-citation data as well as the BRS measure, the dissimilarity values and shortest paths. The compactness measure for the weighted network is smaller than for the un-weighted. When the bibliographic coupling network is utilized it is shown to be less compact than the co-citation network which indicates that the new measure produces results that confirm to an obvious case.
43Ahlgren, P. ; Jarneving, B. ; Rousseau, R.: Requirements for a cocitation similarity measure, with special reference to Pearson's correlation coefficient.
In: Journal of the American Society for Information Science and technology. 54(2003) no.6, S.549-568.
Abstract: Ahlgren, Jarneving, and. Rousseau review accepted procedures for author co-citation analysis first pointing out that since in the raw data matrix the row and column values are identical i,e, the co-citation count of two authors, there is no clear choice for diagonal values. They suggest the number of times an author has been co-cited with himself excluding self citation rather than the common treatment as zeros or as missing values. When the matrix is converted to a similarity matrix the normal procedure is to create a matrix of Pearson's r coefficients between data vectors. Ranking by r and by co-citation frequency and by intuition can easily yield three different orders. It would seem necessary that the adding of zeros to the matrix will not affect the value or the relative order of similarity measures but it is shown that this is not the case with Pearson's r. Using 913 bibliographic descriptions form the Web of Science of articles form JASIS and Scientometrics, authors names were extracted, edited and 12 information retrieval authors and 12 bibliometric authors each from the top 100 most cited were selected. Co-citation and r value (diagonal elements treated as missing) matrices were constructed, and then reconstructed in expanded form. Adding zeros can both change the r value and the ordering of the authors based upon that value. A chi-squared distance measure would not violate these requirements, nor would the cosine coefficient. It is also argued that co-citation data is ordinal data since there is no assurance of an absolute zero number of co-citations, and thus Pearson is not appropriate. The number of ties in co-citation data make the use of the Spearman rank order coefficient problematic.
Themenfeld: Informetrie ; Citation indexing
44Rousseau, R.: Journal evaluation : technical and practical issues.
In: Library trends. 50(2002) no.3, S.418-439.
Abstract: This essay provides an overview of journal evaluation indicators. It highlights the strengths and weaknesses of different indicators, together with their range of applicability. The definition of a "quality journal," different notions of impact factors, the meaning of ranking journals, and possible biases in citation databases are also discussed. Attention is given to using the journal impact in evaluation studies. The quality of a journal is a multifaceted notion. Journals can be evaluated for different purposes, and hence the results of such evaluation exercises can be quite different depending on the indicator(s) used. The impact factor, in one of its versions, is probably the most used indicator when it comes to gauging the visibility of a journal on the research front. Generalized impact factors, over periods longer than the traditional two years, are better indicators for the long-term value of a journal. As with all evaluation studies, care must be exercised when considering journal impact factors as a quality indicator. It seems best to use a whole battery of indicators (including several impact factors) and to change this group of indicators depending on the purpose of the evaluation study. Nowadays it goes without saying that special attention is paid to e-journals and specific indicators for this type of journal.
Anmerkung: Artikel in einem Themenheft "Current theory in library and information science"
45Kretschmer, H. ; Rousseau, R.: Author inflation leads to a breakdown of Lotka's law : in and out of context.
In: Journal of the American Society for Information Science and technology. 52(2001) no.8, S.610-614.
Abstract: Fractional counting of authors of multi-authored papers has been shown to lead to a breakdown of Lotka's Law despite its robust character under most circumstances. Kretschmer and Rousseau use the normal count method of full credit for each author on two five-year bibliographies from each of 13 Dutch physics institutes where high co-authorship is a common occurrence. Kolmogorov-Smirnov tests were preformed to see if the Lotka distribution fit the data. All bibliographies up to 40 authors fit acceptably; no bibliography with a paper with over 100 authors fits the distribution. The underlying traditional "success breeds success" mechanism assumes new items on a one by one basis, but Egghe's generalized model would still account for the process. It seems unlikely that Lotka's Law will hold in a high co-authorship environment.
46Egghe, L. ; Rousseau, R. ; Hooydonk, G. van: Methods for accrediting publications to authors or countries : consequences for evaluation studies.
In: Journal of the American Society for Information Science. 51(2000) no.2, S.145-157.
Abstract: One aim of science evaluation studies is to determine quantitatively the contribution of different players (authors, departments, countries) to the whole system. This information is then used to study the evolution of the system, for instance to gauge the results of special national or international programs. Taking articles as our basic data, we want to determine the exact relative contribution of each coauthor or each country. These numbers are brought together to obtain country scores, or department scores, etc. It turns out, as we will show in this article, that different scoring methods can yield totally different rankings. Conseqeuntly, a ranking between countries, universities, research groups or authors, based on one particular accrediting methods does not contain an absolute truth about their relative importance
47Egghe, L. ; Rousseau, R.: ¬The influence of publication delays on the observed aging distribution of scientific literature.
In: Journal of the American Society for Information Science. 51(2000) no.2, S.158-165.
Abstract: Observed aging curves are influenced by publication delays. In this article, we show how the 'undisturbed' aging function and the publication delay combine to give the observed aging function. This combination is performed by a mathematical operation known as convolution. Examples are given, such as the convolution of 2 Poisson distributions, 2 exponential distributions, a 2 lognormal distributions. A paradox is observed between theory and real data
48Egghe, L. ; Rousseau, R.: Aging, obsolescence, impact, growth, and utilization : definitions and relations.
In: Journal of the American Society for Information Science. 51(2000) no.11, S.1004-1017.
Abstract: The notions aging, obsolescence, impact, growth, utilization, and their relations are studied. It is shown how to correct an observed citation distribution for growth, once the growth distribution is known. The relation of this correction procedure with the calculation of impact measures is explained. More interestingly, we have shown how the influence of growth on aging can be studied over a complete period as a whole. Here, the difference between the so-called average and global aging distributions is the main factor. Our main result is that growth can influence aging but that it does not cause aging. A short overview of some classical articles on this topic is given. Results of these earlier works are placed in the framework set up in this article
49Egghe, L. ; Rousseau, R.: Topological aspects of information retrieval.
In: Journal of the American Society for Information Science. 49(1998) no.13, S.1144-1160.
Abstract: Let (DS, DQ, sim) be a retrieval system consisting of a document space DS, a query space QS, and a function sim, expressing the similarity between a document and a query. Following D.M. Everett and S.C. Cater (1992), we introduce topologies on the document space. These topologies are generated by the similarity function sim and the query space QS. 3 topologies will be studied: the retrieval topology, the similarity topology and the (pseudo-)metric one. It is shown that the retrieval topology is the coarsest of the three, while the (pseudo-)metric is the strongest. These 3 topologies are generally different, reflecting distinct topological aspects of information retrieval. We present necessary and sufficient conditions for these topological aspects to be equal
50Egghe, L. ; Rousseau, R.: ¬A theoretical study of recall and precision using a topological approach to information retrieval.
In: Information processing and management. 34(1998) nos.2/3, S.191-218.
Abstract: Topologies for information retrieval systems are generated by certain subsets, called retrievals. Shows how recall and precision can be expressed using only retrievals. Investigates different types of retrieval systems: both threshold systems and close match systems and both optimal and non optimal retrieval. Highlights the relation with the hypergeometric and some non-standard distributions
51Egghe, L. ; Rousseau, R.: Duality in information retrieval and the hypegeometric distribution.
In: Journal of documentation. 53(1997) no.5, S.499-496.
Abstract: Asserts that duality is an important topic in informetrics, especially in connection with the classical informetric laws. Yet this concept is less studied in information retrieval. It deals with the unification or symmetry between queries and documents, search formulation versus indexing, and relevant versus retrieved documents. Elaborates these ideas and highlights the connection with the hypergeometric distribution
Inhalt: Vgl. auch unter: http://www.emeraldinsight.com/10.1108/EUM0000000007208.
52Egghe, L. ; Rousseau, R.: Averaging and globalising quotients of informetric and scientometric data.
In: Journal of information science. 22(1996) no.3, S.165-170.
Abstract: It is possible, using ISI's Journal Citation Report (JCR), to calculate average impact factors (AIF) for LCR's subject categories but it can be more useful to know the global Impact Factor (GIF) of a subject category and compare the 2 values. Reports results of a study to compare the relationships between AIFs and GIFs of subjects, based on the particular case of the average impact factor of a subfield versus the impact factor of this subfield as a whole, the difference being studied between an average of quotients, denoted as AQ, and a global average, obtained as a quotient of averages, and denoted as GQ. In the case of impact factors, AQ becomes the average impact factor of a field, and GQ becomes its global impact factor. Discusses a number of applications of this technique in the context of informetrics and scientometrics
53Harvey, L. ; Rousseau, R.: Development of text-editing skill : from semantic and syntactic mappings to procedures.
In: Human-computer interaction. 10(1995) no.4, S.345-400.
Abstract: Considers whether joint syntax (a single step linking object and procedure) or disjoint, 2 step, processes are best suited to particular tasks of text editing. Finds that specific procedures are not necessarily faster to use than general ones. users of joint editors consulted the help menu less often and for longer and experienced a greater workload than users of disjoint editors. The experiment shows that general text editing procedures obeying a disjoint systax minimize workload. Specific objects and joint syntax are advanced features that should be reserved for experienced users
54Rousseau, R.: Bradford curves.
In: Information processing and management. 30(1994) no.2, S.267-277.
Abstract: It is shown that generalized Leimkuhler functions give proper fits to a large variety of Bradford curves, including those exhibited a so-called Groos droop or a rising tail
56Rousseau, R.: Use of an existing thesaurus in a knowledge based indexing and retrieval system.
In: Annals of library science and documentation. 38(1991) no.4, S.127-130.
Abstract: A simple heuristic method is proposed to use an existing thesaurus for weighted indexing
57Egghe, L. ; Rousseau, R.: Introduction to informetrics : quantitative methods in library, documentation and information science.
Amsterdam : Elsevier, 1990. XI,450 S.
Compass: Information science / Statistical mathematics
LCSH: Library statistics ; Information science / Statistical methods ; Documentation / Statistical methods ; Library science / Statistical methods
BK: 06.60 / Bibliotheksbenutzung
GHBS: AUB (DU) ; TLZ (DU) ; TKW (DU) ; TWD (DU) ; AYV (DU) ; BCGS (FH K) ; AUX (PB) ; AYQ (PB)
LCC: Z669.8.E38 1990
RVK: AN 70400 Allgemeines / Buch- und Bibliothekswesen, Informationswissenschaft / Bibliothekswesen / Bibliotheksverwaltung / Bibliotheksanalyse, -statistik