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1.
Gabriel-Alexandru Vîiu 《Journal of Informetrics》2018,12(2):401-415
Characteristic scores and scales (CSS) – a well-established scientometric tool for the study of citation counts – have been used to document a striking phenomenon that characterizes citation distributions at high levels of aggregation: irrespective of scientific field and citation window empirical studies find a persistent pattern whereby about 70% of scientific papers belong to the class of poorly cited papers, about 21% belong to the class of fairly cited papers, 6% to that of remarkably cited papers and 3% to the class of outstandingly cited papers. This article aims to advance the understanding of this remarkable result by examining it in the context of the lognormal distribution, a popular model used to describe citation counts across scientific fields. The article shows that the application of the CSS method to lognormal distributions provides a very good fit to the 70–21–6–3% empirical pattern provided these distributions are characterized by a standard deviation parameter in the range of about 0.8–1.3. The CSS pattern is essentially explainable as an epiphenomenon of the lognormal functional form and, more generally, as a consequence of the skewness of science which is manifest in heavy-tailed citation distributions. 相似文献
2.
[目的/意义] 文章的被引频次一直是量化评价一篇论文学术影响力的重要指标。但在不同学科不同年份发表的论文会因该领域研究论文数、引用滞后等因素呈现较大的差异。因此在对比两篇论文时，难以简单依据被引频次的绝对值来评判论文影响力大小。为此，本文设计了一个新的可计算数学模型，使得每篇论文可以有一个标准化的指标，以便对不同学科不同年份发表的论文的学术影响力进行直接比较。[方法/过程] 通过分析2006、2017两年中国科技类学术期刊各学科论文的被引频次分布规律，采用同学科论文被引频次的分布形态最接近对数正态分布的先设条件，提出一种被引频次标准化指数——Paper Citation Standardized Index （简称PCSI，中文"论文引证标准化指数"）。最后以中国科协优秀科技期刊论文评选结果为例，将它们与论文所属学科全部论文进行实证对比研究。[结果/结论] 结果证明，PCSI对不同年份、不同学科论文的被引频次进行了标准化，反映了被引频次的线性差距，是一种较为理想的单篇论文学术影响力比较评价工具。 相似文献
3.
[目的/意义] 文章的被引频次一直是量化评价一篇论文学术影响力的重要指标。但在不同学科不同年份发表的论文会因该领域研究论文数、引用滞后等因素呈现较大的差异。因此在对比两篇论文时，难以简单依据被引频次的绝对值来评判论文影响力大小。为此，本文设计了一个新的可计算数学模型，使得每篇论文可以有一个标准化的指标，以便对不同学科不同年份发表的论文的学术影响力进行直接比较。[方法/过程] 通过分析2006、2017两年中国科技类学术期刊各学科论文的被引频次分布规律，采用同学科论文被引频次的分布形态最接近对数正态分布的先设条件，提出一种被引频次标准化指数——Paper Citation Standardized Index （简称PCSI，中文"论文引证标准化指数"）。最后以中国科协优秀科技期刊论文评选结果为例，将它们与论文所属学科全部论文进行实证对比研究。[结果/结论] 结果证明，PCSI对不同年份、不同学科论文的被引频次进行了标准化，反映了被引频次的线性差距，是一种较为理想的单篇论文学术影响力比较评价工具。 相似文献
4.
Citation numbers are extensively used for assessing the quality of scientific research. The use of raw citation counts is generally misleading, especially when applied to cross-disciplinary comparisons, since the average number of citations received is strongly dependent on the scientific discipline of reference of the paper. Measuring and eliminating biases in citation patterns is crucial for a fair use of citation numbers. Several numerical indicators have been introduced with this aim, but so far a specific statistical test for estimating the fairness of these numerical indicators has not been developed. Here we present a statistical method aimed at estimating the effectiveness of numerical indicators in the suppression of citation biases. The method is simple to implement and can be easily generalized to various scenarios. As a practical example we test, in a controlled case, the fairness of fractional citation count, which has been recently proposed as a tool for cross-discipline comparison. We show that this indicator is not able to remove biases in citation patterns and performs much worse than the rescaling of citation counts with average values. 相似文献
5.
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
6.
《Journal of Informetrics》2023,17(1):101356
Scholarly citations – widely seen as tangible measures of the impact and significance of academic papers – guide critical decisions by research administrators and policy makers. The citation distributions form characteristic patterns that can be revealed by big-data analysis. However, the citation dynamics varies significantly among subject areas, countries etc. The problem is how to quantify those differences, separate global and local citation characteristics. Here, we carry out an extensive analysis of the power-law relationship between the total citation count and the h-index to detect a functional dependence among its parameters for different science domains. The results demonstrate that the statistical structure of the citation indicators admits representation by a global scale and a set of local exponents. The scale parameters are evaluated for different research actors – individual researchers and entire countries – employing subject- and affiliation-based divisions of science into domains. The results can inform research assessment and classification into subject areas; the proposed divide-and-conquer approach can be applied to hidden scales in other power-law systems. 相似文献
7.
Jiang Wu 《Journal of Informetrics》2013,7(1):63-71
Using the dataset based on Thomson Reuters Scientific “Web of Science” the distributions of some well-known indicators, such as h-index and g-index, were investigated, and different citation behaviors across different scientific fields resulting from their field dependences were found. To develop a field-independent index, two scaling methods, based on average citation of subject category and journal, were used to normalize the citation received by each paper of a certain author. The distributions of the generalized h-indices in different fields were found to follow a lognormal function with mean and standard deviation of approximately ?0.8 and 0.8, respectively. A field-independent index fi-index was then proposed, and its distribution was found to satisfy a universal power-law function with scaling exponent α approaching 3.0. Both the power-law and the lognormal universality of the distributions verified the field independence of these indicators. However, deciding which of the scaling methods is the better one is necessary for the validation of the field-independent index. 相似文献
8.
Using an initial dataset consisting of 18.5 million distinct authors and 15 million distinct articles published in the period 2000–2016, which are classified into 29 broad scientific fields, we search for regularities at the individual level for very productive authors with citation distributions of a certain size, and for the existence of a macro-micro relationship between the skewness of a scientific field citation distribution and the characteristics of the individual citation distributions of the authors belonging to the field. Our main results are the following three. Firstly, although the skewness of individual citation distributions varies greatly within each field, their average skewness is of a similar order of magnitude in all fields. Secondly, as in the previous literature, field citation distributions are highly skewed and the degree of skewness is very similar across fields. Thirdly, the skewness of field citation distributions is essentially explained in terms of the average skewness of individual authors, as well as individuals’ differences in mean citation rates and the number of publications per author. These results have important conceptual and practical consequences: to understand the skewness of field citation distributions at any aggregate level we must simply explain the skewness of the individual citation distributions of their very productive authors. 相似文献
9.
For comparisons of citation impacts across fields and over time, bibliometricians normalize the observed citation counts with reference to an expected citation value. Percentile-based approaches have been proposed as a non-parametric alternative to parametric central-tendency statistics. Percentiles are based on an ordered set of citation counts in a reference set, whereby the fraction of papers at or below the citation counts of a focal paper is used as an indicator for its relative citation impact in the set. In this study, we pursue two related objectives: (1) although different percentile-based approaches have been developed, an approach is hitherto missing that satisfies a number of criteria such as scaling of the percentile ranks from zero (all other papers perform better) to 100 (all other papers perform worse), and solving the problem with tied citation ranks unambiguously. We introduce a new citation-rank approach having these properties, namely P100; (2) we compare the reliability of P100 empirically with other percentile-based approaches, such as the approaches developed by the SCImago group, the Centre for Science and Technology Studies (CWTS), and Thomson Reuters (InCites), using all papers published in 1980 in Thomson Reuters Web of Science (WoS). How accurately can the different approaches predict the long-term citation impact in 2010 (in year 31) using citation impact measured in previous time windows (years 1–30)? The comparison of the approaches shows that the method used by InCites overestimates citation impact (because of using the highest percentile rank when papers are assigned to more than a single subject category) whereas the SCImago indicator shows higher power in predicting the long-term citation impact on the basis of citation rates in early years. Since the results show a disadvantage in this predictive ability for P100 against the other approaches, there is still room for further improvements. 相似文献
10.
In the double rank analysis of research publications, the local rank position of a country or institution publication is expressed as a function of the world rank position. Excluding some highly or lowly cited publications, the double rank plot fits well with a power law, which can be explained because citations for local and world publications follow lognormal distributions. We report here that the distribution of the number of country or institution publications in world percentiles is a double rank distribution that can be fitted to a power law. Only the data points in high percentiles deviate from it when the local and world μ parameters of the lognormal distributions are very different. The likelihood of publishing very highly cited papers can be calculated from the power law that can be fitted either to the upper tail of the citation distribution or to the percentile-based double rank distribution. The great advantage of the latter method is that it has universal application, because it is based on all publications and not just on highly cited publications. Furthermore, this method extends the application of the well-established percentile approach to very low percentiles where breakthroughs are reported but paper counts cannot be performed. 相似文献
11.
抽取2005—2006年中山大学公共卫生学院硕士研究生的学位论文共202篇,以其中的148篇MPH学位论文为研究组,54篇公共卫生全日制研究生学位论文为对照组,比较分析了两组学位论文引文规律及信息需求的差异。结果表明,MPH组的引文量及外文文献的引用率均低于全日制组,且引文率及外文文献引用率存在学科间差异;两组引文类型基本一致,但各类引文所占比例不同,普赖斯指数和半衰期也存在差异。建议通过多种方式提高MPH研究生的信息检索技巧、文献吸收能力。 相似文献
12.
文章以中国科学引文数据库（CSCD）的中文核心库科技期刊及其发表的论文为研究样本,运用因子分析法对中文科技期刊原创指数进行实证研究。选取10个衡量期刊原创水平的指数（内核指数、黏性指数、贡献指数、特色指数、专业指数、全媒体指数、数字化指数、首发指数、国际作者指数、国际编纂指数）,使用主成分分析法提取4个原创因子（原创内容因子、品牌特质因子、媒体传播因子、国际化因子）,构建具有3级指标的中文科技期刊原创指数体系。研究表明,中文科技期刊需以原创为本,培育品牌意识,治理学术乱象,增强核心竞争力,打造具有原创力的出版物,以此建立良好的原创生态圈。 相似文献
13.
[目的/意义]确定基于引用关系提取关键文献时各种方法的优缺点、适用场合,从而使用户快速捕捉领域重要文献,掌握领域概貌。[方法/过程]基于文献引用关系,从文献被引频次、文献引用网络、文献共被引网络3个角度,结合HistCite、CiteSpace等软件探讨领域关键文献的识别方法,通过同源数据的实际验证,对不同方法进行判别比较。[结果/结论]基于被引频次的方法更适合选择特定领域中哪些文献对总体文献的科学进步产生重大影响角度提取关键文献,对应的关键文献集合呈现非常分散的特性;基于引用网络的方法更适合从特定领域研究动态提取发展过程中的关键文献,对应的关键文献集合呈现非常明显的集中特性;基于共被引网络的方法更适合从特定领域研究基础角度提取关键文献,对应的关键文献集合呈现较强的集中性,且能发现原始采集中未发现的大量关键文献。 相似文献
14.
O. V. Fedorets 《Scientific and Technical Information Processing》2011,38(3):166-172
The standard impact factor allows one to compare scientific journals only within particular scientific subjects. To overcome
this limitation, another indicator of citation, viz., the thematically weighted impact factor (TWIF), is proposed. This indicator
allows one to compare journals of various subjects and takes the fact that a journal belongs to several subjects into account.
Information on the thematic headings of a journal and the value of a standard impact factor is necessary for calculation of
the indicator. The TWIF, which is calculated according to the citation index of Journal Citation Reports, is investigated in this article. 相似文献
15.
《Journal of Informetrics》2022,16(4):101341
We study an agent-based model for generating citation distributions in complex networks of scientific papers, where a fraction of citations is allotted according to the preferential attachment rule (rich get richer) and the remainder is allocated accidentally (purely at random, uniformly). Previously, we derived and analysed such a process in the context of describing individual authors, but now we apply it to scientific journals in computer and information sciences. Based on the large DBLP dataset as well as the CORE (Computing Research and Education Association of Australasia) journal ranking, we find that the impact of journals is correlated with the degree of accidentality of their citation distribution. Citations to impactful journals tend to be more preferential, while citations to lower-ranked journals are distributed in a more accidental manner. Further, applied fields of research such as artificial intelligence seem to be driven by a stronger preferential component – and hence have a higher degree of inequality – than the more theoretical ones, e.g., mathematics and computation theory. 相似文献
16.
17.
文章对我国6个学科的社科学术期刊3类评价指标及其相互间的相关性进行分析。研究表明:分学科而言,3个特征指标之间相关性不明显;3个转载指标间具有较强的相关关系,特别是综合指数和转载量、转载率之间具有强相关性;除了复合即年指标外,其他引用指标间均呈现出一定程度的正相关关系,影响力指数与其他引用指标间呈现出较强的相关关系,复合影响因子、复合他引影响因子、5年复合影响因子两两间呈强相关关系;期刊特征指标与转载指标、引用指标之间的相关性均不显著。转载指标与引用指标间具有中度的相关关系。评价体系不宜同时使用正相关度较强的多项指标,或者应适当控制其总权重;期刊选文时不应太注重基金论文比、平均引文数等特征指标,应注重论文的学术质量。总体上看,高等院校学报和专业社科期刊相比,3类评价指标之间的相关性差异不明显,高等院校学报人不必因为影响力的原因而纠结是否进行专业化发展,而应该根据自身资源条件选择发展策略。 相似文献
18.
《Journal of Informetrics》2007,1(3):185-192
In this paper, we propose two methods for scoring scientific output based on statistical quantile plotting. First, a rescaling of journal impact factors for scoring scientific output on a macro level is proposed. It is based on normal quantile plotting which allows to transform impact data over several subject categories to a standardized distribution. This can be used in comparing scientific output of larger entities such as departments working in quite different areas of research. Next, as an alternative to the Hirsch index [Hirsch, J.E. (2005). An index to quantify an individuals scientific research output. Proceedings of the National Academy of Sciences of the United States of America, 102(46), 16569–16572], the extreme value index is proposed as an indicator for assessment of the research performance of individual scientists. In case of Lotkaian–Zipf–Pareto behaviour of citation counts of an individual, the extreme value index can be interpreted as the slope in a Pareto–Zipf quantile plot. This index, in contrast to the Hirsch index, is not influenced by the number of publications but stresses the decay of the statistical tail of citation counts. It appears to be much less sensitive to the science field than the Hirsch index. 相似文献
19.
The scientific impact of a publication can be determined not only based on the number of times it is cited but also based on the citation speed with which its content is noted by the scientific community. Here we present the citation speed index as a meaningful complement to the h index: whereas for the calculation of the h index the impact of publications is based on number of citations, for the calculation of the speed index it is the number of months that have elapsed since the first citation, the citation speed with which the results of publications find reception in the scientific community. The speed index is defined as follows: a group of papers has the index s if for s of its Np papers the first citation was at least s months ago, and for the other (Np ? s) papers the first citation was ≤s months ago. 相似文献
20.
针对Z指数不能实现跨学科领域期刊评价的缺陷,文章通过引入学科规范化引文影响力修正不同学科的引用差异,改进Z指数并提出ZCNCI指数。通过分析ZCNCI指数与Z指数、P指数、SNIP、标准化特征因子、影响因子百分位等指标的相关性和差异性,验证ZCNCI指数跨学科期刊评价的效力。结果表明,ZCNCI指数延续了Z指数综合反映期刊数量、质量和被引分布特征的优势,与Z指数、P指数、标准化特征因子的相关性较高,且克服了SNIP、影响因子百分位的评价缺陷,在跨学科期刊评价中的综合表现较好。ZCNCI指数具有跨学科期刊评价效力,可用于跨学科期刊评价。 相似文献