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In a recent paper, Egghe [Egghe, L. (in press). Mathematical derivation of the impact factor distribution. Journal of Informetrics] presents a mathematical analysis of the rank-order distribution of journal impact factors. The analysis is based on the central limit theorem. We criticize the empirical relevance of Egghe's analysis. More specifically, we argue that Egghe's analysis relies on an unrealistic assumption and we show that the analysis is not in agreement with empirical data. 相似文献
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《Journal of Informetrics》2008,2(1):101-105
Egghe and Proot [Egghe, L., & Proot, G. (2007). The estimation of the number of lost multi-copy documents: A new type of informetrics theory. Journal of Informetrics] introduce a simple probabilistic model to estimate the number of lost multi-copy documents based on the numbers of retrieved ones. We show that their model in practice can essentially be described by the well-known Poisson approximation to the binomial. This enables us to adopt a traditional maximum likelihood estimation (MLE) approach which allows the construction of (approximate) confidence intervals for the parameters of interest, thereby resolving an open problem left by the authors. We further show that the general estimation problem is a variant of a well-known unseen species problem. This work should be viewed as supplementing that of Egghe and Proot [Egghe, L., & Proot, G. (2007). The estimation of the number of lost multi-copy documents: A new type of informetrics theory. Journal of Informetrics]. It turns out that their results are broadly in line with those produced by this rather more robust statistical analysis. 相似文献
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《Journal of Informetrics》2007,1(1):59-67
Statistical distributions in the production of information are most often studied in the framework of Lotkaian informetrics. In this paper, we recall some results of basic theory of Lotkaian informetrics, then we transpose methods (Theorem 1) applied to Lotkaian distributions by Leo Egghe (Theorem 2) to the exponential distributions (Theorem 3, Theorem 4). We give examples and compare the results (Theorem 5). Finally, we propose to widen the problem using the concept of exponential informetric process (Theorem 6). 相似文献
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《Journal of Informetrics》2014,8(1):241-251
This study established a technological impact factor (TIF) derived from journal impact factor (JIF), which is proposed to evaluate journals from the aspect of practical innovation. This impact factor mainly examines the influence of journal articles on patents by calculating the number of patents cited to a journal divided by the number of articles published in that particular journal. The values of TIF for five-year (TIF5) and ten-year (TIF10) periods at the journal level and aggregated TIF values (TIFAGG_5 and TIFAGG_10) at the category level were provided and compared to the JIF. The results reveal that journals with higher TIF values showed varied performances in the JCR, while the top ten journals on JIF5 showed consistent good performance in TIFs. Journals in three selected categories – Electrical & Electronic Engineering, Research & Experimental Medicine, and Organic Chemistry – showed that TIF5 and TIF10 values are not strongly correlated with JIF5. Thus, TIFs can provide a new indicator for evaluating journals from the aspect of practical innovation. 相似文献
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J.C. Valderrama-Zurian D. Melero-Fuentes R. Aleixandre-Benavent 《Journal of Informetrics》2019,13(1):434-448
Eponyms are very common in some scientific fields, and they are a fundamental part of the language and historical culture of researchers, as many people have given their names to procedures, laws, formulas, tests, hypotheses, diseases and numerous processes. Despite being etymologically empty terms, some of these names are so deeply rooted that it would be very difficult to do without them. In this paper, 2313 eponyms are analysed from 16,787 bibliometric documents indexed in the Web of Science Core Collection database. A total of 187 eponyms were identified, most of which belong to the areas of information science, statistics and economics. The most frequent eponyms were Hirsch (325), Lotka (214), Bradford (186), Price (146), Egghe (76), Garfield (74) and Zipf (59). Among the most frequent eponyms, the most contemporary, Hirsch and Egghe, were referenced in the same year they were incorporated into the scientific literature. All conceptual networks have the term bibliometrics as their core, except the Hirsch network, in which the term h-index is more central. Currently, the debate continues in the scientific literature, with arguments for and against the use of eponyms. 相似文献
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篇均来源期刊标准影响(SNIP)为荷兰学者Moed教授于2010年提出的全新期刊评价指标,旨在对不同主题领域的期刊影响力进行评价,为验证这一评价指标在期刊评价实践中的效用,利用SPSS18.0数据统计分析软件对Scopus数据库中24种外文期刊的SNIP与SJR、h指数以及影响因子进行实证对比分析;以CSSCI为来源数据库统计分析国内6种图书情报学期刊的IF值与SNIP值。分析结果证明,SNIP与其他3个指标之间存在较强的相关性,在期刊评价实践中具有可行性。 相似文献
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In a recent paper in the Journal of Informetrics, Habibzadeh and Yadollahie [Habibzadeh, F., & Yadollahie, M. (2008). Journal weighted impact factor: A proposal. Journal of Informetrics, 2(2), 164–172] propose a journal weighted impact factor (WIF). Unlike the ordinary impact factor, the WIF of a journal takes into account the prestige or the influence of citing journals. In this communication, we show that the way in which Habibzadeh and Yadollahie calculate the WIF of a journal has some serious problems. Due to these problems, a ranking of journals based on WIF can be misleading. We also indicate how the problems can be solved by changing the way in which the WIF of a journal is calculated. 相似文献
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根据武书连"2012中国大学综合实力排行榜"和2012年版《中国科技期刊引证报告》的数据,对综合实力排名前10位的高校(排名)和其学报影响因子按学科分别进行了统计学相关性分析,同时对全国自然科学、人文社科类高校学报影响因子与其所属高校的排名进行了统计学相关性分析。结果表明,在一定条件下高校学报的影响因子与其高校排名存在一定相关性,但总体而言,相关性不强。 相似文献
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Despite the huge amount of literature concerning the h-index, few papers have been devoted to its statistical analysis when a probabilistic distribution is assumed for citation counts. The present contribution mainly aims to divulge the inferential techniques recently introduced by Pratelli et al. (2012), by explaining the details for proper point and set estimation of the theoretical h-index. Moreover, some new achievements on simultaneous inference – addressed to produce suitable scholar comparisons – are carried out. Finally, the analysis of the citation dataset for the Nobel Laureates (in the last five years) and for the Fields medallists (from 2002 onward) is considered in order to exemplify the theoretical issues. 相似文献
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Ludo Waltman Nees Jan van Eck Thed N. van Leeuwen Martijn S. Visser 《Journal of Informetrics》2013,7(2):272-285
The SNIP (source normalized impact per paper) indicator is an indicator of the citation impact of scientific journals. The indicator, introduced by Henk Moed in 2010, is included in Elsevier's Scopus database. The SNIP indicator uses a source normalized approach to correct for differences in citation practices between scientific fields. The strength of this approach is that it does not require a field classification system in which the boundaries of fields are explicitly defined.In this paper, a number of modifications that were recently made to the SNIP indicator are explained, and the advantages of the resulting revised SNIP indicator are pointed out. It is argued that the original SNIP indicator has some counterintuitive properties, and it is shown mathematically that the revised SNIP indicator does not have these properties. Empirically, the differences between the original SNIP indicator and the revised one turn out to be relatively small, although some systematic differences can be observed. Relations with other source normalized indicators proposed in the literature are discussed as well. 相似文献
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Experimental data [Mansilla, R., Köppen, E., Cocho, G., & Miramontes, P. (2007). On the behavior of journal impact factor rank-order distribution. Journal of Informetrics, 1(2), 155–160] reveal that, if one ranks a set of journals (e.g. in a field) in decreasing order of their impact factors, the rank distribution of the logarithm of these impact factors has a typical S-shape: first a convex decrease, followed by a concave decrease. In this paper we give a mathematical formula for this distribution and explain the S-shape. Also the experimentally found smaller convex part and larger concave part is explained. If one studies the rank distribution of the impact factors themselves, we now prove that we have the same S-shape but with inflection point in μ, the average of the impact factors. These distributions are valid for any type of impact factor (any publication period and any citation period). They are even valid for any sample average rank distribution. 相似文献
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The g-index is a well-known index for measuring and comparing the output of scientific researchers, which has been introduced by Leo Egghe in 2006 as an improvement of the Hirsch-index. This article gives an axiomatic characterization of the g-index in terms of three natural axioms. 相似文献
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Michael Schreiber 《Journal of Informetrics》2010,4(4):647-651
The Hirsch index h and the g index proposed by Egghe as well as the f index and the t index proposed by Tol are shown to be special cases of a family of Hirsch index variants, based on the generalized mean with exponent p. Inequalities between the different indices are derived from the generalized mean inequality. The graphical determination of the indices is shown for one example. 相似文献
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Lutz Bornmann Alexander Tekles Helena H. Zhang Fred Y. Ye 《Journal of Informetrics》2019,13(4):100979
Lee et al. (2015) – based on Uzzi et al. (2013) – and Wang et al. (2017) proposed scores based on cited references (cited journals) data which can be used to measure the novelty of papers (named as novelty scores U and W in this study). Although previous research has used novelty scores in various empirical analyses, no study has been published up to now – to the best of our knowledge – which quantitatively tested the convergent validity of novelty scores: do these scores measure what they propose to measure? Using novelty assessments by faculty members (FMs) at F1000Prime for comparison, we tested the convergent validity of the two novelty scores (U and W). FMs’ assessments do not only refer to the quality of biomedical papers, but also to their characteristics (by assigning certain tags to the papers): for example, are the presented findings or formulated hypotheses novel (tags “new findings” and “hypothesis”)? We used these and other tags to investigate the convergent validity of both novelty scores. Our study reveals different results for the novelty scores: the results for novelty score U are mostly in agreement with previously formulated expectations. We found, for instance, that for a standard deviation (one unit) increase in novelty score U, the expected number of assignments of the “new finding” tag increase by 7.47%. The results for novelty score W, however, do not reflect convergent validity with the FMs’ assessments: only the results for some tags are in agreement with the expectations. Thus, we propose – based on our results – the use of novelty score U for measuring novelty quantitatively, but question the use of novelty score W. 相似文献
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《Journal of Informetrics》2014,8(3):491-492
We clarify the content of the article “Impact coverage of the success-index” by Leo Egghe and show that its real contribution is showing that for a Lotkaian system it is possible to determine a threshold value as a function of the system's parameters such that the value of the success-index corresponding to this threshold value is equal to the h-index and similar indices. It is observed that these results do not strictly hold in discrete systems. 相似文献
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This study investigates the relationship between cultural orientation (individualistic or collectivistic culture) and consumers' attribution styles (dispositional and situational attributions) as well as the consequences of attribution styles on brand evaluation and purchase intention. The study also examines how people perceive different types of negative celebrity information (self-oriented and other-oriented negative information) and how their identification with a celebrity endorser affects their response to negative information. The findings suggest that culture influences how consumers – having been exposed to negative celebrity information – make attributions. Dispositional attributions lead to more negative brand evaluation as well as to negative purchase intention. Other-oriented negative information leads to, among Korean consumers, more negative brand evaluation. Finally, the study found that consumers highly identified with a celebrity endorser are less likely to be influenced by negative celebrity information. 相似文献
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