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Document Server@UHasselt (58.393 recursos)

Repository of the University of Hasselt containing publications in the fields of statistics, computer science, information strategies and material from the Institute for behavioural sciences.


Mostrando recursos 1 - 20 de 47

  1. Multiple auhorship in biochemistry and other fields; a case study of the journal of biological chemistry trhoughout 1905-1988

    Yitzhaki, Moshe; Ben-Tamar, David
    Large samples of papers published in the Journal of Biological Chemistry were checked in order to study the multiple authorship pattern throughout the period from 1905 t o 1988 i n an internationally leading scientific journal with an especially high " citation impact". Both measures of mean number of authors per paper and proportion of multi-authored papers show that there has been a consistent growth during nost of the period, best described by a "steps model", expressing recurring sharp increases following relatively steady periods. From 1975 on, however, growth has been accelerating, when measured at five-year intervals. Findings do not support...

  2. Cluster analysis of title overlap in twenty-one library collections in western New York

    Wilson, Frances L.; McGrath, William E.
    Title overlap of 21 libraries in western New York, was described by the Jaccard similarity coefficient. The coefficient has two features appropriate for describing overlap : it is self-normalizing and avoids mutual lack of ownership as a basis for similarity . The matrix of 210 coefficients was submitted t o 4 methods of cluster analysis : single linkage, complete linkage, average linkage and Ward's. Cophenetic correlation coefficients for single, complete, and average linkage, 0.55, 0.69, and 0.74, respectively, suggested that the average linkage was best. Ward's was judged poorest on the basis of visual inspection. Two clusters fran the average linkage method, with...

  3. Bibliometric analysis of publication activity of a scientific research institute

    Vinkler, Peter
    The present paper sumnarizes bi bliometric indicators used for evaluation of publication activity and research progress of research teams in an academic research institute . The main goal of the application of the regularly calculated indicators is to help the researchers in forming an appropriate publication strategy. The Lotka distribution of papers among researchers showed correlation with personal characteristics (position and scientific degree held). The Bradford distribution of papers among journals published by research teams working in different subfields revealed great differences among the subfields. A new indicator (Publication Concentration) is also suggested which yields the percentage of journals used by a research team to publish half of its papers in a...

  4. Representing Canadian geophysics : a bibliometric approach

    Todorov, R.
    Various bibliometric methods are used to obtain an alternative (quantitative) representation of Canadian publication activity in geophysics. First , an online technique for data gathering i s applied to create appropriate sets o f document records from the 1988 INSPEC file and to count selected bibliographic characteristics by using directly the software implemented in the host system. Then, the appearance and co-appearance of classification subdivisions (headings) in the chosen records are utilized to describe the subject structure of Canadian geophysics in terms of headings and their links. Multivariate technique is applied to display the results in the form of two-dimensional inclusion maps.

  5. Chaotic structures in informetrics

    Tabah, Albert N.; Saber, Aaron Jaan
    A sample space of the number of publications in polymer chemistry over a five year period has been subjected to time series data analysis. The technique uses autocorrelation and a subsequent FFT (fast Fourier transform). The analysis shows that the sample space is small but the data appears to have chaotic behaviour. Recomnendations for future work and applications are identified.

  6. Journal productivity in economics

    Ravichandra Rao, I.K.
    A bibliography in economics consisting of 4130 articles from 744 journals i s examined to study the scattering of articles in various journals. It has been observed that the empirical distribution of articles is reverse-J shape with a long tail and distribution is highly positively skewed. Further, it has been observed that 99 % of the journals contain 90 % o f the articles. Only one percent of the journals contribute nearly 10 % of the periodical literature in economics. This study suggest that the negative binomial distribution does not fit the empirical distribution of articles in economics. However, it fits very well...

  7. A citation analysis of clinical trials; are definitive studies less cited than others ?

    Peritz, Bluma C.
    A citation analysis of 316 clinical trials published in 1979 and 1980 in two major medical journals : New England Journal of Medicine and Lancet arrives at an apparently paradoxical finding.: large trials, carried out according t o modern designs involving randomized and double-blind allocation procedures, tend to be less cited than other, less rigorous studies. The explanation put forward in this paper revolves around the idea that heuristic value is an important determinant of citedness. Since studies designed to yield final conclusions are likely to be preceded by smaller and more tentative trials , new ideas, concepts and approaches are more...

  8. Quality assessment of schistosomiasis literature

    Pao, Miranda Lee; Goffman, William
    Average impact per paper, a refinement of the use of impact factor, was used to assess the quality of publications produced by a small group of sponsored researchers. The average impact per paper associated with half of the literature published by grantees has been shown to exceed those taken from the total literature at large. Moreover, this indicator appears to be stable over the five years tested. Compared with the schistosomiasis literature as a whole, the subset contributed by the grantees has consistently produced higher averaqe impact scores. These results stronqly suggest that substantial research support sustained over a significant period could foster high quality research.

  9. Production and dissemination of the Mexian biomemdical journals, with some considerations of the latin American/Caribbean region

    Macias-Chapula, Cesar A.
    A quantitative analysis of 67 Mexican Biomedical Journals (MBMJ), according to their editorship, frequency of publication, subject classification and "in-depth" biomedical coverage, was performed. The inclusion of these journals in six major secondary sources (Index Medicus, Excerpta Medica, Biological Abstracts, Index Medicus Latinoamericano, Chemical Abstracts, and Science Citation Index) was also examined. A comparative analysis o f the MBMJ with other Latin American and Caribbean Biomedical Journals (LABMJ), as covered by these sources, was performed. Science Citation Index' Journal Citation Reports was used to analyse the citation pattern of the only MBMJ (Archives de Investigacion Medica) covered by Science Citation Index. Again, a comparison...

  10. Text to reference ratios in scientific journals

    Little, Anne E.; Harris, Roma M.; Nicholls, Paul T.
    I n 1987, Peter Junars, the editor of Limnology and Oceanography, reported that the ratio of printed pages of text t o nunber of references had decreased during the period 1980 to 1987. I n other words, authors were using an increasing nunber o f references - an observation which was o f sane concern because Limnozoology and Oceanography publishes only a fixed nunber of pages per year. I n the present study, an attempt was made t o detenine whether journals from other scientific disciplines (botany, physical chemistry, and geology) were undergoing a similar change i n the ratio of text t...

  11. Social stratification of authors revealed from the coauthorship network

    Kretschmer, Hildrun
    Seven bibliographies frm the fields of medicine, physics and social sciences were used. The authors were classified by groups i n accordance with the number of publications per author. Studies were made t o detenine the statistically expected number of coauthorships by proceeding fran assuming an independence of coauthorship between authors from the number of their publications. Hypothesis : The proportion of the sum of coauthorship found between authors with the same number of publications t o the sun of the statistically expected one i s larger than the proportion of the sum of coauthorships found between authors with a different...

  12. Growth and citation selection rates in rapidly growing sciences from date stacking and bibliographic databases

    Hall, D.H.
    Growth of literature in a field was taken as an indicator of the growth of the field as a whole. Stacked citation dataatid the yearly accumulation of literature were found for 3 fields i n the geosciences : Geology and Geophysics of Mars (1962-1985), Magnetic Stratigraphy (1957-1977) and early Seismology (1600-1750). The yearly accumulation for the first two fields was found from a computerized bibliographic database (GEOREF). That for early Seismology was found from a published bibliography. Phases of logistic growth and of exponential growth as well as several periods of constant rate of selection of citations were found.

  13. Criteria of Gaussian/non-Gaussian nature of distrubution and populations

    Haitun, S.D.
    The use of Gaussian distributions in approximations of samples of non-Gaussian populations leads to irreproducible results. Non-Gaussian distribution ~ should be used i n these cases. The criteria of Gaussianhon-Gaussian nature for distributions are distinct , thus making it possible to unequivocally show which distribution and at which values o f parameters i s Gaussianlnon-Gaussian. For populations, the criteria are more blurred. An alternative is to use only Zipfian distributions as approximations. The correctness o f various distributions (GIGP, GW etc) and the methods of their use in informetrics and scientometrics is analysed.

  14. The cumulative advantage function. A mathematical formulation based on conditional expectations and its application to scientometric distributions

    Glänzel, Wolfgang; Schubert, Andras
    Cumulative advantage principle is a specific law underlying several social, particularly , bibliometric and scientometric processes. This phenomenon was described by single- and multiple-urn models (Price (1976). Tague (1981)). A theoretical model for cumulative advantage growth was developed by Schubert and Glaenzel (1984). This paper presents an exact measure of the cumulative advantage effect based on conditional expectations. For a given bibliometric random variable X (e.g. publication activity , citation rate) the cumulative advantage function i s defined as d k ) = E(iK-k)[(X-k) b O)/E(X). The 'extent of advantage' is studied on the basis of limit properties of this function. The behavior...

  15. Elements of concentration theory

    Egghe, Leo
    We review some concentration measures proposed in the literature and present a set of principles that good concentration measures must fulfill . We moreover look into some of the consequences of these principles. The transfer principle is extended to yield a new family of principles, denoted E(p), but a concentration measure can only satisfy E(p) for at most one p. We discuss briefly the issue of sensitivity to transfers and show that Heine's dispersion measures are related to some well-known concentration measures.

  16. New Bradfordian laws equivalent with old Lotka, evolving from a source-item argument

    Egghe, Leo
    Based on the duality techniques in a previous paper (L. Egghe, The duality o f informetric systems with applications to the empirical laws), we study general relationships between Bradfordian and Lotka laws. This results in new Bradfordian laws which are B equivalent with the well-known Lotka laws $(n) = - (a > 1). The new method also sheds some light on the question why a < 2 i s more common than a > 2. Also, the general law of Leimkuhler, as found by Rousseau, i s reproved and shown to be equivalent with the above mentioned laws. Fitting methods are applied...

  17. The unification of addresses in scientific publications

    De Bruin, R.E.; Moed, H.F.
    Addresses in scientific publications contain a large number of variations. This phenomenon has serious consequences for the availability of information and for evaluative bibliometrics. Organizations are difficult to identify and become "scattered' in rankings. To solve this problem, we developed a strategy of unification, i.e. classification of all variations by one name. To begin with, we sorted on the first part of the address. Next, we unified these addresses by the name of an overall organization (such as a university). We did so by analyzing the publication data. For some countries we performed further research in handbooks and encyclopedias. We solved the problem...

  18. Empirical prediction of library circulations based on negative binomial processes

    Burrell, Quentin L.
    The empirical method for prediction o f library circulations i n the presence of ageing recently proposed by Burrell i s extended t o cover mixtures of negative binomial processes. This makes the method more flexible but requires assumptions about an unknown parameter. Predictions using this method are compared with the earlier ones based on mixtures of Poisson processes.

  19. Perfect Bradford multipliers : a definition and empirical investigation

    Brooks, Terrence A.
    This study analyzed two literatures for Bradford multipliers calculated b the methods o f Egghe (forthcoming) and Goffman and Warren (1969). Bradford partitionings were evaluated with Pratt's (1977) index of class concentration. Perfect Bradford partitions had a Pratt index of zero. Bradford multipliers associated with these partitions were defined as perfect Bradford multipliers. A search for partitions with a Pratt index of zero revealed that both literatures have many perfect multipliers. An implication o f these results i s that the Bradford multiplier can take a range of values. It was observed t h a t there i s usually one perfect...

  20. Biblio-, sciento-, infor-metrics?? what are we talking about ?

    Brookes, B.C.
    This paper traces the origins of informatics, scientometrics and informetrics in the USSR and Hungary; the origins of information science, information studies and bibliometrics in Britain and the USA, and their interactions with library studies. Finaly, three different contexts are suggested in which the three '-metrics' have distinctive and important rules.

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