Although bibliometrics has been a separate research field for many years, there is still no uniformity in the way bibliometric analyses are applied to individual researchers. Therefore, this study aims to set up proposals how to evaluate individual researchers working in the natural and life sciences. 2005 saw the introduction of the h index, which gives information about a researcher's productivity and the impact of his or her publications in a single number (h is the number of publications with at least h citations); however, it is not possible to cover the multidimensional complexity of research performance and to undertake inter-personal comparisons with this number. This study therefore includes recommendations for a set of indicators to be used for evaluating researchers. Our proposals relate to the selection of data on which an evaluation is based, the analysis of the data and the presentation of the results.
How to analyse percentile impact data meaningfully in bibliometrics: The statistical analysis of distributions, percentile rank classes and top-cited papers
Which percentile-based approach should be preferred for calculating normalized citation impact values? An empirical comparison of five approaches including a newly developed citation-rank approach (P100)
How to improve the prediction based on citation impact percentiles for years shortly after the publication date?
Bornmann、Leydesdorff和Wang的研究结果表明，考虑期刊影响力可以提高对长期引文影响力的预测。本文进一步探讨了在短引文窗口的基础上，通过考虑期刊影响力和其他变量，如作者数、被引文献数和页数，改进引文影响力测量的可能性。该数据集包含1980年发表并在Web of Science（WoS，Thomson Reuters）中索引的475，391篇期刊论文，以及这些论文的所有年度引用计数（从1980年到2010年）。作为引文影响力的指标，我们使用了使用Hazen（1914）方法计算的引文数量。我们的研究结果表明，引文影响测量确实可以改进：如果在统计分析中考虑影响引文影响的一般因素，长期引文影响的解释方差可以大大增加。然而，这种增长只有在使用出版后不久的年份时才能看到，而在使用以后的年份时则看不到。
The substantive and practical significance of citation impact differences between institutions: Guidelines for the analysis of percentiles using effect sizes and confidence intervals
How much do different ways of calculating percentiles influence the derived performance indicators? - A case study
文献计量指标可以通过比较特定的引文记录与参考文献集的数量来确定。然而，在计算引文数量时存在着一种模糊性，因为通常在百分位数等级之间的边界处会发现大量具有相同引用计数的论文。本案例研究的引用期刊欧洲物理学快报（EPL）在比较所有的物理论文从Web of Science显示的偏差，由于不同的方式来处理并列论文的高被引出版物的百分比的评估。如果被引用次数达到阈值的论文都被认为是高引用或都被认为不是高引用，则可能会出现强烈的偏倚。
Percentiles are statistics pointing to the standing of a paper's citation impact relative to other papers in a given citation distribution. Percentile Ranks (PRs) often play an important role in evaluating the impact of scholars, institutions, and lines of study. Because PRs are so important for the assessment of scholarly impact, and because citation practices differ greatly across time and fields, various percentile approaches have been proposed to time- and field-normalize citations. Unfortunately, current popular methods often face significant problems in time- and field-normalization, inc…
Using percentile shares, one can visualize and analyze the skewness in bibliometric data across disciplines and over time. The resulting figures can be intuitively interpreted and are more suitable for detailed analysis of the effects of independent and control variables on distributions than regression analysis. We show this by using percentile shares to analyze so-called "factors influencing citation impact" (FICs; e.g., the impact factor of the publishing journal) across year and disciplines. All articles (n= 2,961,789) covered by WoS in 1990 (n= 637,301), 2000 (n= 919,485), and 2010 (n= 1,…
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 devi…
Recently, the integrated impact indicator (I3) indicator was introduced where citations are weighted in accordance with the percentile rank class of each publication in a set of publications. I3 can also be used as a field-normalized indicator. Field-normalization is common practice in bibliometrics, especially when institutions and countries are compared. Publication and citation practices are so different among fields that citation impact is normalized for cross-field comparisons. In this study, we test the ability of the indicator to discriminate between quality levels of papers as defined …
Remaining problems with the "New Crown Indicator" (MNCS) of the CWTS
Waltman等人（2010年; arXiv：1003.2167）在其题为“Towards a new crown indicator：some theoretical considerations”的文章中指出，莱顿CWTS的“旧冠指标”在数学上不一致，应该采用“新冠指标”中应用的标准化。“尽管我们现在同意统计标准化，但“新冠指标”继承了“旧”指标的科学计量学问题，即把期刊的学科类别作为标准，对科学领域之间的引用行为差异进行标准化。我们进一步注意到，“平均值”不是测量偏态分布之间差异的适当统计量。在不改变“MNS”的缩写的情况下，可以定义“中位数标准化引文评分”。“这将使新冠指标与百分位数方法直接相关，例如，美国国家科学委员会的科学和工程指标（2010年）中使用的百分位数方法。根据定义，中位数等于第50百分位数。因此，该指标可以很容易地扩展为1%（=第99百分位）最高引用论文（Bornmann等人，印刷中）。必须使用非参数统计的表面上的缺点被可能的精度增益所补偿。
The prediction of the long-term impact of a scientific article is challenging task, addressed by the bibliometrician through resorting to a proxy whose reliability increases with the breadth of the citation window. In the national research assessment exercises using metrics the citation window is necessarily short, but in some cases is sufficient to advise the use of simple citations. For the Italian VQR 2011-2014, the choice was instead made to adopt a linear weighted combination of citations and journal metric percentiles, with weights differentiated by discipline and year. Given the strateg…
We have studied the efficiency of research in the EU by a percentile-based citation approach that analyzes the distribution of country papers among the world papers. Going up in the citation scale, the frequency of papers from efficient countries increases while the frequency from inefficient countries decreases. In the percentile-based approach, this trend, which is permanent at any citation level, is measured by the ep index that equals the Ptop 1%/Ptop 10% ratio. By using the ep index we demonstrate that EU research on fast-evolving technological topics is less efficient than the world aver…
There are different citation habits in the research fields that influence the obsolescence of the research literature. We analyze the distinctive obsolescence of research literature in disciplinary journals in eight scientific subfields based on cited references distribution, as a synchronous approach. We use both Negative Binomial (NB) and Poisson distributions to capture this obsolescence. The corpus being examined is published in 2019 and covers 22,559 papers citing 872,442 references. Moreover, three measures to analyze the tail of the distribution are proposed: (i) cited reference surviva…
The use of bibliometric indicators would simplify research assessments. The 2014 Research Excellence Framework (REF) is a peer review assessment of UK universities, whose results can be taken as benchmarks for bibliometric indicators. In this study we use the REF results to investigate whether the ep index and a top percentile of most cited papers could substitute for peer review. The probability that a random university's paper reaches a certain top percentile in the global distribution of papers is a power of the ep index, which can be calculated from the citation-based distribution of unive…
The top 1 percent most highly cited articles are watched closely as the vanguards of the sciences. Using Web of Science data, one can find that China had overtaken the USA in the relative participation in the top 1 percent in 2019, after outcompeting the EU on this indicator in 2015. However, this finding contrasts with repeated reports of Western agencies that the quality of Chinese output in science is lagging other advanced nations, even as it has caught up in numbers of articles. The difference between the results presented here and the previous results depends mainly upon field normalizat…
We conducted a large-scale analysis of around 10,000 scientific articles, from the period 2007-2016, to study the bibliometric or formal aspects influencing citations. A transversal analysis was conducted disaggregating the articles into more than one hundred scientific areas and two groups, one experimental and one control, each with a random sample of around five thousand documents. The experimental group comprised a random sample of the top 1% most cited articles in each field and year of publication (highly cited articles), and the control group a random sample of the remaining articles in…
How are excellent (highly cited) papers defined in bibliometrics? A quantitative analysis of the literature
在过去的几十年里，卓越研究的主题受到越来越多的关注（在科学政策中），越来越多的文献计量学研究已经出版，涉及优秀论文。然而，在这些研究中使用了许多不同的方法来识别优秀论文。本定量分析的文献已经进行，以获得这些方法的概述和“平均”或“最常见”的文献计量学的做法的指示。在Web of Science上搜索得到了321篇论文，涉及“高引用”，“最多引用”，“顶级引用”和“最频繁引用”。在321篇文献中，有16篇无法用于本研究。在本研究分析的约80%的论文中，提供了一个定量定义来识别优秀论文。对于涉及绝对数量的定义，选择一定数量的顶级引用论文（58%）或引用次数最少的论文（17%）。大约23%的人从事百分位等级的工作。在这些论文中，有一个前7.6%（算术平均值）或前3%（中位数）的算术平均值。排名前1%的人在论文中使用频率最高，其次是排名前10%的人。有了本研究中提出的阈值，未来将有可能根据文献计量学家的“平均”或“最常见”实践来识别优秀论文。
