A modification of the h-index: The hm-index accounts for multi-authored manuscripts

In order to take multiple co-authorship appropriately into account, a straightforward modification of the Hirsch index was recently proposed. Fractionalised counting of the papers yields an appropriate measure which is called the h_m-index. The effect of this procedure is compared in the present work with other variants of the h-index and found to be superior to the fractionalised counting of citations and to the normalization of the h-index with the average number of authors in the h-core. Three fictitious examples for model cases and one empirical case are analysed.     

Woeginger's axiomatisation of the h-index and its relation to the g-index, the h-index and the R-index

Recently Woeginger [Woeginger, G. H. (2008-a). An axiomatic characterization for the Hirsch-index. Mathematical Social Sciences. An axiomatic analysis of Egghe's g-index. Journal of Informetrics] introduced a set of axioms for scientific impact measures. These lead to a characterization of the h-index. In this note we consider a slight generalization and check which of Woeginger's axioms are satisfied by the g-index, the h⁽²⁾-index and the R²-index.     

Examples of simple transformations of the h-index: Qualitative and quantitative conclusions and consequences for other indices

General results on transformations on information production processes (IPPs), involving transformations of the h-index and related indices, are applied in concrete, simple cases: doubling the production per source, doubling the number of sources, doubling the number of sources but halving their production, halving the number of sources but doubling their production (fusion of sources) and, finally, special cases of general power law transformations. In each case we calculate concrete transformation formulae for the h-index h (transformed into h*) and we discuss when we have h* < h, h* = h or h* > h.

These results are then extended to some other h-type indices such as the g-index, the R-index and the weighted h-index.     

Definitions of time series in citation analysis with special attention to the h-index

The structure of different types of time series in citation analysis is revealed, using an adapted form of the Frandsen–Rousseau notation. Special cases where this approach can be used include time series of impact factors and time series of h-indices, or h-type indices. This leads to a tool describing dynamic aspects of citation analysis. Time series of h-indices are calculated in some specific models.     

Citation impact analysis of top ranked computer science journals and their rankings

Citation based approaches, such as the impact factor and h-index, have been used to measure the influence or impact of journals for journal rankings. A survey of the related literature for different disciplines shows that the level of correlation between these citation based approaches is domain dependent. We analyze the correlation between the impact factors and h-indices of the top ranked computer science journals for five different subjects. Our results show that the correlation between these citation based approaches is very low. Since using a different approach can result in different journal rankings, we further combine the different results and then re-rank the journals using a combination method. These new ranking results can be used as a reference for researchers to choose their publication outlets.     

Publication patterns of award-winning forest scientists and implications for the Australian ERA journal ranking

Publication patterns of 79 forest scientists awarded major international forestry prizes during 1990-2010 were compared with the journal classification and ranking promoted as part of the ‘Excellence in Research for Australia’ (ERA) by the Australian Research Council. The data revealed that these scientists exhibited an elite publication performance during the decade before and two decades following their first major award. An analysis of their 1703 articles in 431 journals revealed substantial differences between the journal choices of these elite scientists and the ERA classification and ranking of journals. Implications from these findings are that additional cross-classifications should be added for many journals, and there should be an adjustment to the ranking of several journals relevant to the ERA Field of Research classified as 0705 Forestry Sciences.     

Analysis of the distribution of cited journals according to their positions in the h-core of citing journal listed in Journal Citation Reports

The aim of this study is to analyze some properties of the distribution of journals that are cited in the h-core of citing journals listed in the Journal Citation Reports. Data were obtained from the 2011 edition of JCR available for universities in Spain. The citing journal matrix available in JCR was used to identify the cited journals that appear most frequently in the h-core. The results show that about 70% of citing journals occupy positions other than the first one in the set of journals cited by them. Some properties of the distribution of cited journals that appear in the h-core are also studied, such as the cost, in terms of citations, of occupying a given position, and the spectrum of positions (distribution of frequencies with which a given cited journal appears in different positions). The measures calculated here could be used to define new scientometric indicators.     

欧洲因子(The Euro-FactorTM)--一种评价欧洲期刊质量的新工具

影响因子存在40多年来在科学界备受争论,欧洲因子的提出,对于评价科研水平及期刊质量的标准与方式具有深远的意义。文章介绍了欧洲期刊质量因子(EF)产生的背景与计算公式。     

引用质量加权影响因子评价学术期刊研究-以CSSCI图书情报学期刊评价为例

构建一种考虑引用质量的加权影响因子:IFwh指数,该指数既能反映影响因子与H指数计算简便、设计巧妙的优点,又体现SJR指数与Eigenfactor计算算法中考虑引用质量的思想,以期客观科学地反映期刊的影响力。在详细阐述IFwh指数设计思想的基础上,以CSSCI收录的我国图书情报学期刊为例进行实证研究,一方面检验利用IFwh指数评价学术期刊的可行性;另一方面通过分析IFwh指数评价与影响因子、H指数评价以及CSSCI评价的关系,研究IFwh指数的特性。IFwh指数同样适用于学科专业和科教人员等层面的学术影响力评价。     

Ranking journals using social choice theory methods: A novel approach in bibliometrics

We use data on economic, management and political science journals to produce quantitative estimates of (in)consistency of the evaluations based on six popular bibliometric indicators (impact factor, 5-year impact factor, immediacy index, article influence score, SNIP and SJR). We advocate a new approach to the aggregation of journal rankings. Since the rank aggregation is a multicriteria decision problem, ranking methods from social choice theory may solve it. We apply either a direct ranking method based on the majority rule (the Copeland rule, the Markovian method) or a sorting procedure based on a tournament solution, such as the uncovered set and the minimal externally stable set. We demonstrate that the aggregate rankings reduce the number of contradictions and represent the set of the single-indicator-based rankings better than any of the six rankings themselves.     

A multilevel meta-analysis of studies reporting correlations between the h index and 37 different h index variants

This paper presents the first meta-analysis of studies that computed correlations between the h index and variants of the h index (such as the g index; in total 37 different variants) that have been proposed and discussed in the literature. A high correlation between the h index and its variants would indicate that the h index variants hardly provide added information to the h index. This meta-analysis included 135 correlation coefficients from 32 studies. The studies were based on a total sample size of N = 9005; on average, each study had a sample size of n = 257. The results of a three-level cross-classified mixed-effects meta-analysis show a high correlation between the h index and its variants: Depending on the model, the mean correlation coefficient varies between .8 and .9. This means that there is redundancy between most of the h index variants and the h index. There is a statistically significant study-to-study variation of the correlation coefficients in the information they yield. The lowest correlation coefficients with the h index are found for the h index variants MII and m index. Hence, these h index variants make a non-redundant contribution to the h index.     

MEDLINE数据库收录的中文医学期刊来源指标分析

对MEDLINE数据库收录的中文生物医学相关期刊的来源指标进行了分析,并与期刊所在学科的各指标的平均值作了对比。结果发现,MEDLINE收录的中文医学期刊文献量不大,平均每刊刊载约260篇,每篇论文平均有5个作者、17条参考文献,文献的引用半衰期为6.175年。MEDLINE收录的中文医学期刊并不侧重海外论文的发表,似乎能吸引更多的基金论文。     

JCR五年期影响因子探析

使用期刊引证报告(JCR)6015种期刊数据,以统计学方法探索性地分析5年期影响因子IF5的特点.结果显示,IF5作为具有代表性的平均性期刊评价指标,能更好地反映多数期刊被引高峰,总体符合布拉德福分布.IF5与2年期影响因子IF存在排序相关,也有显著统计学差异,两者测评结果在较好和较差期刊上相对一致,但在多数水平居中的期刊上存在区别.最后,给出Ifa指数测度两种影响因子的差别和Ifb指数综合两种影响因子的评价信息.     

Measuring the Quality of Contributions of Saudi Authors to LIS Journals Using Journal Impact Factor (JIF), SCImago Journal Rank (SJR), and Google Scholar Metrics (GSM)

This research study evaluates the quality of articles published by Saudi and expatriate authors in foreign Library and Information Science (LIS) journals using three popular metrics for ranking journals—Journal Impact Factor (JIF), SCImago Journal Rank (SJR), and Google Scholar Metrics (GSM). The reason for using multiple metrics is to see how closely or differently journals are ranked by the three different methods of citation analysis. However, the 2012 JIF list of journals is too small, almost half the size of the SJR and GSM lists, which inhibited one-to-one comparison among the impact factors of the thirty-six journals selected by Saudi authors for publishing articles. Only seventeen journals were found common to all the three lists, limiting the usefulness of the data. A basic problem is that Saudi LIS authors generally lack the level of competency in the English language required to achieve publication in the most prominent LIS journals. The study will have implications for authors, directors, and deans of all types of academic libraries; chairmen and deans of library schools; and the Saudi Library Association. Hopefully these entities will take necessary steps to prepare and motivate both academics and practicing librarians to improve the quality of their research and publications and thus get published in higher ranked journals.     

Coverage and citation impact of oncological journals in the Web of Science and Scopus

This paper reviews a number of studies comparing Thomson Scientific’s Web of Science (WoS) and Elsevier’s Scopus. It collates their journal coverage in an important medical subfield: oncology. It is found that all WoS-covered oncological journals (n = 126) are indexed in Scopus, but that Scopus covers many more journals (an additional n = 106). However, the latter group tends to have much lower impact factors than WoS covered journals. Among the top 25% of sources with the highest impact factors in Scopus, 94% is indexed in the WoS, and for the bottom 25% only 6%. In short, in oncology the WoS is a genuine subset of Scopus, and tends to cover the best journals from it in terms of citation impact per paper. Although Scopus covers 90% more oncological journals compared to WoS, the average Scopus-based impact factor for journals indexed by both databases is only 2.6% higher than that based on WoS data. Results reflect fundamental differences in coverage policies: the WoS based on Eugene Garfield’s concepts of covering a selective set of most frequently used (cited) journals; Scopus with broad coverage, more similar to large disciplinary literature databases. The paper also found that ‘classical’, WoS-based impact factors strongly correlate with a new, Scopus-based metric, SCImago Journal Rank (SJR), one of a series of new indicators founded on earlier work by Pinski and Narin [Pinski, G., & Narin F. (1976). Citation influence for journal aggregates of scientific publications: Theory, with application to the literature of physics. Information Processing and Management, 12, 297–312] that weight citations according to the prestige of the citing journal (Spearman’s rho = 0.93). Four lines of future research are proposed.     

Journal ranking should depend on the level of aggregation

Journal ranking is becoming more important in assessing the quality of academic research. Several indices have been suggested for this purpose, typically on the basis of a citation graph between the journals. We follow an axiomatic approach and find an impossibility theorem: any self-consistent ranking method, which satisfies a natural monotonicity property, should depend on the level of aggregation. Our result presents a trade-off between two axiomatic properties and reveals a dilemma of aggregation.