共查询到20条相似文献，搜索用时 31 毫秒
1.
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
2.
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
3.
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. 相似文献
4.
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
5.
Journal weighted impact factor: A proposal 总被引：3，自引：0，他引：3
The impact factor of a journal reflects the frequency with which the journal's articles are cited. It is the best available measure of journal quality. For calculation of impact factor, we just count the number of citations, no matter how prestigious the citing journal is. We think that impact factor as a measure of journal quality, may be improved if in its calculation, we not only take into account the number of citations, but also incorporate a factor reflecting the prestige of the citing journals relative to the cited journal. In calculation of this proposed “weighted impact factor,” each citation has a coefficient (weight) the value of which is 1 if the citing journal is as prestigious as the cited journal; is >1 if the citing journal is more prestigious than the cited journal; and is <1 if the citing journal has a lower standing than the cited journal. In this way, journals receiving many citations from prestigious journals are considered prestigious themselves and those cited by low-status journals seek little credit. By considering both the number of citations and the prestige of the citing journals, we expect the weighted impact factor be a better scientometrics measure of journal quality. 相似文献
6.
Journal metrics are employed for the assessment of scientific scholar journals from a general bibliometric perspective. In this context, the Thomson Reuters journal impact factors (JIFs) are the citation-based indicators most used. The 2-year journal impact factor (2-JIF) counts citations to one and two year old articles, while the 5-year journal impact factor (5-JIF) counts citations from one to five year old articles. Nevertheless, these indicators are not comparable among fields of science for two reasons: (i) each field has a different impact maturity time, and (ii) because of systematic differences in publication and citation behavior across disciplines. In fact, the 5-JIF firstly appeared in the Journal Citation Reports (JCR) in 2007 with the purpose of making more comparable impacts in fields in which impact matures slowly. However, there is not an optimal fixed impact maturity time valid for all the fields. In some of them two years provides a good performance whereas in others three or more years are necessary. Therefore, there is a problem when comparing a journal from a field in which impact matures slowly with a journal from a field in which impact matures rapidly. In this work, we propose the 2-year maximum journal impact factor (2M-JIF), a new impact indicator that considers the 2-year rolling citation time window of maximum impact instead of the previous 2-year time window. Finally, an empirical application comparing 2-JIF, 5-JIF, and 2M-JIF shows that the maximum rolling target window reduces the between-group variance with respect to the within-group variance in a random sample of about six hundred journals from eight different fields. 相似文献
7.
Bibliometric data indexed through the Institute for Scientific Information were analyzed for 45 communication journals. Several measures were included to identify the most widely cited journals in the field, including (a) journal impact factor, (b) five-year journal impact, (c) article influence, and (d) journal relatedness. Results serve to expand on findings by Feeley (2008) with respect to overall and within-field influence of communication journals whose analysis covered 2002 through 2005 and 19 journals. Results indicate stability in journal impact ratings over time and several journals (e.g., Communication Research, Human Communication Research, Journal of Communication, Communication Monographs, and Communication Theory) are highly central in the communication journal citation network. 相似文献
8.
[目的/意义] 分析JCR最新公布的"影响因子百分位"指标的特点以及其对期刊评价的影响。[方法/过程] 从影响因子百分位的内涵分析入手,比较其与影响因子的统计学特征,在因子分析的基础上,采用多元回归和分位数回归研究影响因子百分位与其他文献计量指标之间的关系,同时采用Spearman相关系数分析其与其他文献计量指标的关系。[结果/结论] 研究结果表明,影响因子百分位改变了影响因子的统计学特征;影响因子较低的一些期刊,转换成影响因子百分位后相对值更低,其他期刊转换成影响因子百分位后相对值更高;影响因子百分位与其他文献计量指标相关程度中等;当影响因子百分位较低时,影响因子相关指标的弹性系数较高,当影响因子百分位处于中等时,总量指标及特征因子指标的回归系数较低;影响因子百分位并不适宜作为其中一个指标用于期刊多属性评价。 相似文献
9.
Ioana Robu Denisa Marineanu Ileana Aciu Sally Wood‐Lamont 《Health information and libraries journal》2001,18(2):91-98
The paper articulates the problems of journal publication in a relatively small country such as Romania where locally (i.e. nationally) published journals include most of the national medical scientific output. The starting point was a study ordered by the Cluj University of Medicine and Pharmacy Scientific Council, for the purpose of obtaining an objectively ranked list of all current Romanian biomedical journals that could be used in the evaluation of the scientific activity of the university academic staff. Sixty‐five current biomedical journals were identified—of which more than half were new titles that had appeared over the past 5 years. None of these are included in the Science Citation Index or Journal Citation Reports (JCR). A set of criteria was used for ranking the journals: peer review, inclusion in international databases, publication time lag, language of articles and abstracts, journal specific index and domestic impact factor. The period covered, along with tools and formulas used are presented. The problems of Romanian biomedical journals as well as ways of improving publishing standards are discussed. Also emphasized is the necessity for increased awareness in the medical scholarly community and the role of the library in this respect. 相似文献
10.
The journal impact factor (JIF) has been questioned considerably during its development in the past half-century because of its inconsistency with scholarly reputation evaluations of scientific journals. This paper proposes a publication delay adjusted impact factor (PDAIF) which takes publication delay into consideration to reduce the negative effect on the quality of the impact factor determination. Based on citation data collected from Journal Citation Reports and publication delay data extracted from the journals’ official websites, the PDAIFs for journals from business-related disciplines are calculated. The results show that PDAIF values are, on average, more than 50% higher than JIF results. Furthermore, journal ranking based on PDAIF shows very high consistency with reputation-based journal rankings. Moreover, based on a case study of journals published by ELSEVIER and INFORMS, we find that PDAIF will bring a greater impact factor increase for journals with longer publication delay because of reducing that negative influence. Finally, insightful and practical suggestions to shorten the publication delay are provided. 相似文献
11.
《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
12.
基于引用期刊质量的影响因子修正法 总被引：1，自引：0，他引：1
长期以来学术期刊影响因子的计算仅仅统计被引用文章的篇数而没有考虑引用期刊的学术质量,这种计算方法有不尽合理之处.认为在计算影响因子时应充分考虑引用期刊的质量,建议以引用文献的期刊质量为权重对原影响因子公式进行修正.经统计学模拟计算表明,修正后的公式能更客观地对期刊进行评价,这将有利于建立起更公正、合理的期刊评价体系. 相似文献
13.
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. 相似文献
14.
This paper focuses on a fresh and fair way to determine a ranking of science journals according to the “number of citations-to
and articles published,” data used by SCI Journal Citation Reports of ISI to determine journal ranking by “impact factor.”
Impact is considered a latent variable defined by a set of items (citations and articles published). The theoretical background
is Item Response Theory, which suggests that, if we can understand how each item in a set of items operates with an object,
then we can estimate a measure for the object. The Rasch model is the most common formulation of that theory. This technique
is here applied to the citations and articles published of 62 medical journals (objects) to provide a Rasch measure for these
journals which is compared with the current “impact factor” computation. 相似文献
15.
自然科学期刊自引对影响因子的"调控" 总被引：14，自引：0，他引：14
本文利用《中国科技期刊引证报告》,重新计算了其中几个学科的一些期刊除去自引后的影响因子,并对去除前和去除后的影响因子与期刊排名进行了对比,以考察期刊自引对影响因子和期刊排名的影响。调查发现目前个别期刊过度自引已经使期刊排名发生了失真。最后对如何遏制这种现象提出了一些建议。 相似文献
16.
《Journal of Informetrics》2014,8(1):162-174
We have developed a (freeware) routine for “Referenced Publication Years Spectroscopy” (RPYS) and apply this method to the historiography of “iMetrics,” that is, the junction of the journals Scientometrics, Informetrics, and the relevant subset of JASIST (approx. 20%) that shapes the intellectual space for the development of information metrics (bibliometrics, scientometrics, informetrics, and webometrics). The application to information metrics (our own field of research) provides us with the opportunity to validate this methodology, and to add a reflection about using citations for the historical reconstruction. The results show that the field is rooted in individual contributions of the 1920s to 1950s (e.g., Alfred J. Lotka), and was then shaped intellectually in the early 1960s by a confluence of the history of science (Derek de Solla Price), documentation (e.g., Michael M. Kessler's “bibliographic coupling”), and “citation indexing” (Eugene Garfield). Institutional development at the interfaces between science studies and information science has been reinforced by the new journal Informetrics since 2007. In a concluding reflection, we return to the question of how the historiography of science using algorithmic means—in terms of citation practices—can be different from an intellectual history of the field based, for example, on reading source materials. 相似文献
17.
Antonio Quesada 《Journal of Informetrics》2009,3(2):158-160
The Hirsch index is a number that synthesizes a researcher's output. It is the maximum number h such that the researcher has h papers with at least h citations each. Woeginger [Woeginger, G. J. (2008a). An axiomatic characterization of the Hirsch-index. Mathematical Social Sciences, 56(2), 224–232; Woeginger, G. J. (2008b). A symmetry axiom for scientific impact indices. Journal of Informetrics, 2(3), 298–303] characterizes the Hirsch index when indices are assumed to be integer-valued. In this note, the Hirsch index is characterized, when indices are allowed to be real-valued, by adding to Woeginger's monotonicity two axioms in a way related to the concept of monotonicity. 相似文献
18.
Aspasia Togia 《Behavioral & Social Sciences Librarian》2013,32(2):86-102
The purpose of this study was to examine the impact factor of cognitive psychology journals indexed in the Science and Social Sciences edition of Journal Citation Reports (JCR) database over a period of 10 consecutive years. Cognitive psychology journals were indexed in 11 different subject categories of the database. Their mean impact factor ranged from 1.580 to 2.526. In relation to the subject categories of the Social Sciences edition, cognitive psychology journals were placed between the fourth and the sixth position for the years 2007–2009. Lower positions were observed in relation to the categories in the Science edition. Calculation of the intraclass correlation coefficient showed that cognitive psychology journals were relatively stable in the examined period. 相似文献
19.
中文期刊影响因子与网络影响因子和外部链接数的关系研究 总被引：49，自引：2，他引：47
学术期刊是科学信息的重要载体,而Internet是方便信息交流的新兴场所.因此,现在越来越多的学术期刊建立了自己的网站,于是期刊网站的评价也越来越受到人们的关注.本文以部分工程类中文期刊为例,利用AllTheWeb搜索它们网站的外部链接数,并计算其网络影响因子,然后将中国科学技术信息研究所(ISTIC)2001年底公布的2000年期刊影响因子与它们一一对应比较,发现期刊的影响因子与期刊网站的网络影响因子和外部链接数之间均存在着有意义的相关关系,因此,网站的外部链接数和网络影响因子均可作为网站评价的重要指标. 相似文献
20.
Carmelita Pickett 《资料收集管理》2013,38(4):260-275
This study analyzes the coverage of black studies journals as compared to women's studies journals in Web of Science, Academic Search Complete, and ArticleFirst. This study also examines black studies bibliographies and directories to identify journals that are suitable for inclusion in Journal Citation Reports and consequently Web of Science and evaluates seven black studies journals using the Thomson Reuters journal selection process. 相似文献