Early Mendeley readers correlate with later citation counts

Counts of the number of readers registered in the social reference manager Mendeley have been proposed as an early impact indicator for journal articles. Although previous research has shown that Mendeley reader counts for articles tend to have a strong positive correlation with synchronous citation counts after a few years, no previous studies have compared early Mendeley reader counts with later citation counts. In response, this first diachronic analysis compares reader counts within a month of publication with citation counts after 20 months for ten fields. There are moderate or strong correlations in eight out of ten fields, with the two exceptions being the smallest categories (n?=?18, 36) with wide confidence intervals. The correlations are higher than the correlations between later citations and early citations, showing that Mendeley reader counts are more useful early impact indicators than citation counts.     

What factors are associated with increasing co-authorship in the social sciences? A case study of Danish Economics and Political Science

We examine the relative strength of short-term citation counts, bibliometric measures such as journal impact factors, and journal rankings in terms of predicting long-run citations. Using a set of articles published in sixty of the highest reputation economics journals in 1994, we find that citations received over fairly short windows (between 1 and 2 years after publication) are much stronger predictors of long-run citation counts compared with journal impact factors or other journal rankings. Our results are robust to a series of robustness checks. These findings suggest department heads and tenure and promotion committees should place greater weight on short-term citations as opposed to article placement when making personnel decisions.     

Comparison of downloads,citations and readership data for two information systems journals

In our article we compare downloads from ScienceDirect, citations from Scopus and readership data from the social reference management system Mendeley for articles from two information systems journals (“Journal of Strategic Information Systems” and “Information and Management”) published between 2002 and 2011. Our study shows a medium to high correlation between downloads and citations (Spearman r = 0.77/0.76) and between downloads and readership data (Spearman r = 0.73/0.66). The correlation between readership data and citations, however, was only medium-sized (Spearman r = 0.51/0.59). These results suggest that there is at least “some” difference between the two usage measures and the citation impact of the analysed information systems articles. As expected, downloads and citations have different obsolescence characteristics. While the highest number of downloads are usually made in the publication year and immediately afterwards, it takes several years until the citation maximum is reached. Furthermore, there was a re-increase in the downloads in later years which might be an indication that citations also have an effect on downloads to some degree.     

The expansion of Google Scholar versus Web of Science: a longitudinal study

Web of Science (WoS) and Google Scholar (GS) are prominent citation services with distinct indexing mechanisms. Comprehensive knowledge about the growth patterns of these two citation services is lacking. We analyzed the development of citation counts in WoS and GS for two classic articles and 56 articles from diverse research fields, making a distinction between retroactive growth (i.e., the relative difference between citation counts up to mid-2005 measured in mid-2005 and citation counts up to mid-2005 measured in April 2013) and actual growth (i.e., the relative difference between citation counts up to mid-2005 measured in April 2013 and citation counts up to April 2013 measured in April 2013). One of the classic articles was used for a citation-by-citation analysis. Results showed that GS has substantially grown in a retroactive manner (median of 170 % across articles), especially for articles that initially had low citations counts in GS as compared to WoS. Retroactive growth of WoS was small, with a median of 2 % across articles. Actual growth percentages were moderately higher for GS than for WoS (medians of 54 vs. 41 %). The citation-by-citation analysis showed that the percentage of citations being unique in WoS was lower for more recent citations (6.8 % for citations from 1995 and later vs. 41 % for citations from before 1995), whereas the opposite was noted for GS (57 vs. 33 %). It is concluded that, since its inception, GS has shown substantial expansion, and that the majority of recent works indexed in WoS are now also retrievable via GS. A discussion is provided on quantity versus quality of citations, threats for WoS, weaknesses of GS, and implications for literature research and research evaluation.     

Bibliometric analysis of diabetes mellitus research output from Middle Eastern Arab countries during the period (1996–2012)

The main objective of this study was to analyze research productivity originating from Middle East Arab (MEA) countries in the field of diabetes mellitus (DM). Data from January 1, 1996 till December 31, 2012 were searched for documents with specific words in diabetes as a “source title” and a list of 13 MEA countries as affiliation country. Research productivity was evaluated based on number of publications, citation analysis, indexing in Institute for Scientific Information and impact factor (IF). The 13 MEA countries published a total of 479 documents in 41 diabetes journals. This number represents 0.75 % of the total documents produced globally in the field of DM. The number of published documents increased by around fivefold from early 2000 to 2012. Of the 41 journal titles retrieved, 24 (58.5 %) had their IF listed in the journal citation reports 2012. Forty-two documents (14.5 %) were published in journals that had no official IF. The total number of citations for documents published from MEA countries in the field of DM, at the time of data analysis, was 5,565 with an h index of 35. The median (inter-quartile range) citation for documents from the 13 MEA countries was 4 (1–11). The top productive institution in the field of DM was United Arab Emirates University with 51 documents (10.6 %). Authors from MEA countries collaborated mostly with authors in countries like United Kingdom, USA, and Germany. The present data show promising and relatively good diabetes research productivity in MEA countries especially after 2008.     

Nitrogen research at watershed scale: a bibliometric analysis during 1959–2011

Because of enhanced anthropogenic nitrogen input, eutrophication, hypoxia, and acidification threaten the health of aquatic ecosystems. To better understand the current state of research and emerging trends in this area, a bibliometric approach was applied to quantitatively evaluate global nitrogen research at the watershed scale. Using 9,748 articles selected from among 10,163 returned by a search in the Science Citation Index Expanded (SCI-Expanded) database from 1900 to 2011, spatial and temporal characteristics of the articles, authors, institutions, countries, and keywords are presented, and focal research areas are derived. Compared with the annual increase in all articles in the SCI-Expanded (4.5 %), the studies on nitrogen in watersheds increased more quickly (11.2 %), indicating an increasing interest in this area. The relationship between authors and their output was evaluated by a two-step function, in which 6,074 authors (26.8 %) publishing on this topic were key scientists who contributed 56.4 % of the total articles. Based on the number of authors, first authors, international collaborators, and citations, four types of authors were analyzed using cluster methods. The influence of the authors, institutions and countries was also analyzed in terms of publication and citation, and a co-occurrence analysis was used to assess cooperation among countries and research hotpots. The keywords were compared among countries to assist our understanding of interests of research and modes. From the analysis of the primary subjects and the co-occurrence of keywords, studies involving nitrogen’s environmental effects, the nitrogen process and models are increasing, which indicates that they are likely to become a primary research focus in the near future.     

On the relationship between citations of publication output and Hirsch index h of authors: conceptualization of tapered Hirsch index h T, circular citation area radius R and citation acceleration a

The nature of the empirical proportionality constant A in the relation L = Ah ² between total number of citations L of the publication output of an author and his/her Hirsch index h is analyzed using data of the publication output and citations for six scientists elected to the membership of the Royal Society in 2006 and 199 professors working in different institutions in Poland. The main problem with the h index of different authors calculated by using the above relation is that it underestimates the ranking of scientists publishing papers receiving very high citations and results in high values of A. It was found that the value of the Hirsch constant A for different scientists is associated with the discreteness of h and is related to the tapered Hirsch index h _T by A ^1/2 ≈ 1.21h _T. To overcome the drawback of a wide range of A associated with the discreteness of h for different authors, a simple index, the radius R of circular citation area, defined as R = (L/π)^1/2 ≈ h, is suggested. This circular citation area radius R is easy to calculate and improves the ranking of scientists publishing high-impact papers. Finally, after introducing the concept of citation acceleration a = L/t ² = π(R/t)² (t is publication duration of a scientist), some general features of citations of publication output of Polish professors are described in terms of their citability. Analysis of the data of Polish professors in terms of citation acceleration a shows that: (1) the citability of the papers of a majority of physics and chemistry professors is much higher than that of technical sciences professors, and (2) increasing fraction of conference papers as well as non-English papers and engagement in administrative functions of professors result in decreasing citability of their overall publication output.     

Detecting latent referential articles based on their vitality performance in the latest 2 years

In this paper, we propose a methodology to detect latent referential articles through a universal, citation-based investigation. We discuss articles’ dynamic vitality performance, concealed in their citation distributions, in order to understand the mechanisms that govern which articles are likely to be referenced in the future. Articles have diverse vitality performances expressed in the amount of citations obtained in different time periods. Through an examination of the correlation between articles’ future citation count and their past citations, we establish the optimal time period during which it is best to forecast articles’ future referential possibilities. The results show that the latest 2 years is the optimal time period. In other words, the correlation between the articles’ future citation count and their past citation count reaches a maximum value in the most recent 2-year period. The articles with a higher vitality performance in the most recent 2 years have a higher ratio of being cited as references in the future. These results help, not only, in understanding mechanisms of generating references, but also provide an additional indicator for decision makers to evaluate the academic performance of individuals according to their citation performance in the latest 2 years.     

Methodological quality in clinical trials and bibliometric indicators: no evidence of correlations

Citation frequencies and journal impact factors (JIFs) are being used more and more to assess the quality of research and allocate research resources. If these bibliometric indicators are not an adequate predictor of research quality, there could be severe negative consequences for research. To analyse to which extent citation frequencies and journal impact factors correlate with the methodological quality of clinical research articles included in an SBU systematic review of antibiotic prophylaxis in surgery. All 212 eligible original articles were extracted from the SBU systematic review “Antibiotic Prophylaxis in Surgery” and categorized according to their methodological rigourness as high, moderate or low quality articles. Median of citation frequencies and JIFs were compared between the methodological quality groups using Kruskal–Wallis non-parametric test. An in-depth study of low-quality studies with higher citation frequencies/JIFs was also conducted. No significant differences were found in median citation frequencies (p = 0.453) or JIFs (p = 0.185) between the three quality groups. Studies that had high citation frequencies/JIFs but were assessed as low-quality lacked control groups, had high dropout rates or low internal validity. This study of antibiotic prophylaxis in surgery does not support the hypothesis that bibliometric indicators are a valid instrument for assessing methodological quality in clinical trials. This is a worrying observation, since bibliometric indicators have a major influence on research funding. However, further studies in other areas are needed.     

A quantitative analysis of Antarctic related articles in humanities and social sciences appearing in the world core journals

To demonstrate the importance and the actual research situation of Antarctic studies in the humanities and social sciences, we collected data from the SSCI and A&HCI covering a period of over 100 years and focused on the number of articles published each year, major journals, types of document, authors and their countries publishing the most articles, collaboration, the major research subjects covered, and citations. Comparisons were also made with the Arctic studies to show some similarities and differences. The results suggest that the research in the fields of humanities and social sciences has been in the long-run developing without interruption over 100 years. With regard to the number of articles in high-capacity journals, Geographical Journal performs best, followed by the Petermanns Geographische Mitteilungen and Scottish Geographical Magazine. The documentation is rather scattered without a strong cohesion, while book review and article are the two most common types of document. There haven’t many stable collaborated teams on Antarctic topics. Joyner, Savours, and Beck are the three authors having the highest number of publications. USA is the most active country while the most active research institute is University of Tasmania in Australia. The Antarctic expedition has been the main theme lasted for centuries. In addition, the research in the fields of humanities and social sciences has generated a lot of high-impact articles, among which the article entitled “Chemical concentrations of pollutant lead aerosols, terrestrial dusts and sea salts in Greenland and Antarctic snow strata” enjoys the highest citation counts.     

The effect of document types and sizes on the scaling relationship between citations and co-authorship patterns in management journals

The aim of this paper is to explore the power-law relationship between citation-based performance (CBP) and co-authorship patterns for papers in management journals by analyzing its behavior according to the type of documents (articles and reviews) and the number of pages of documents. We analyzed 36,241 papers that received 239,172 citations. The scaling exponent of CBP for article papers was larger than for reviews. Citations to articles increased 2^1.67 or 3.18 times each time the number of article papers published in a year in management journals doubled. The citations to reviews increased 2^1.29 or 2.45 times each time the number of reviews published in a year in management journals doubled. The scaling exponent for the power-law relationship of citation-based performance according to number of pages of papers was 1.44 ± 0.05 for articles and 1.25 ± 0.05 for reviews. The citations to articles increased faster than citation to reviews. The scaling exponent for the power-law of citation-based performance to co-authored articles was higher than single-authored articles. For reviews the scaling exponent was the same for the relationship between citation based performance and the number of reviews. Citations increased faster in single authored reviews than co-authored reviews.     

A bibliometric analysis of the performance of <Emphasis Type="Italic">Water Research</Emphasis>

This paper presents a detailed chronological survey of papers published in the journal titled Water Research which started publication since 1967. This current investigation reviews publication patterns between 1967 and 2008. An analysis of the research performance according to publication output, distribution of words in article title, author keywords, and keywords plus. Performances of countries, institutes, and authors, including total, single, collaborative, first author, and corresponding author publications were analyzed. The most-frequently cited articles each year and the articles of the highest impact in 2008 were also reported. Results showed that “activated sludge” was the most frequently used author keyword, followed by “adsorption,” and “drinking water.” Authors from 114 different countries/territories published in the journal, with the most articles submitted by authors from the USA.     

Citation time window choice for research impact evaluation

This paper aims to inform choice of citation time window for research evaluation, by answering three questions: (1) How accurate is it to use citation counts in short time windows to approximate total citations? (2) How does citation ageing vary by research fields, document types, publication months, and total citations? (3) Can field normalization improve the accuracy of using short citation time windows? We investigate the 31-year life time non-self-citation processes of all Thomson Reuters Web of Science journal papers published in 1980. The correlation between non-self-citation counts in each time window and total non-self-citations in all 31 years is calculated, and it is lower for more highly cited papers than less highly cited ones. There are significant differences in citation ageing between different research fields, document types, total citation counts, and publication months. However, the within group differences are more striking; many papers in the slowest ageing field may still age faster than many papers in the fastest ageing field. Furthermore, field normalization cannot improve the accuracy of using short citation time windows. Implications and recommendations for choosing adequate citation time windows are discussed.     

The use of citation speed to understand the effects of a multi-institutional science center

The extent to which an article attracts citations has long been of interest. However, recent research has emphasized not just the receipt but also the pacing of citation. Citation speed has been shown to be affected by journal prestige and self-citation but also public funding of research. Amidst these viewpoints, this paper explores the speed of article citation of a multi-institutional, multi-disciplinary publicly funded research center relative to that of a comparison group of articles. Results indicate that articles by authors affiliated with the center are significantly more likely to have early-cited papers within the year of publication than the random comparison group, with controls by field also being significant. Implications for the ability of a publicly funded center to attract attention toward articles are discussed.     

Selecting scientific excellence through committee peer review - A citation analysis of publications previously published to approval or rejection of post-doctoral research fellowship applicants

Summary We investigated committee peer review for awarding long-term fellowships to post-doctoral researchers as practiced by the Boehringer Ingelheim Fonds (B.I.F.) - a foundation for the promotion of basic research in biomedicine. Assessing the validity of selection decisions requires a generally accepted criterion for research impact. A widely used approach is to use citation counts as a proxy for the impact of scientific research. Therefore, a citation analysis for articles published previous to the applicants' approval or rejection for a B.I.F. fellowship was conducted. Based on our model estimation (negative binomial regression model), journal articles that had been published by applicants approved for a fellowship award (n = 64) prior to applying for the B.I.F. fellowship award can be expected to have 37% (straight counts of citations) and 49% (complete counts of citations) more citations than articles that had been published by rejected applicants (n = 333). Furthermore, comparison with international scientific reference values revealed (a) that articles published by successful and non-successful applicants are cited considerably more often than the “average” publication and (b) that excellent research performance can be expected more of successful than non-successful applicants. The findings confirm that the foundation is not only achieving its goal of selecting the best junior scientists for fellowship awards, but also successfully attracting highly talented young scientists to apply for B.I.F. fellowships.     

An improved method for analyzing square scientometric transaction matrices

Modeling the number of citations from one journal to another may be done by assuming independent contributions from the referencing journal and from the cited journal. Empirical and theoretical evidence, however, indicates that self-citations are different from interjournal citations. For this reason a model is proposed that separates the analysis of selfcitations from inter-citations. In addition, a model is proposed that adjusts the expected citation counts by the journal to journal similarity. Computational procedures for fitting coefficients of the models to the observed citation pattern are described along with a statistical method for evaluating the validity of the model.     

Correlation between impact and collaboration

We obtained data of statistical significance to verify the intuitive impression that collaboration leads to higher impact. We selected eight scientific journals to analyze the correlations between the number of citations and the number of coauthors. For different journals, the single-authored articles always contained the lowest citations. The citations to those articles with fewer than five coauthors are lower than the average citations of the journal. We also provided a simple measurement to the value of authorship with regards to the increase number of citations. Compared to the citation distribution, similar but smaller fluctuations appeared in the coauthor distribution. Around 70% of the citations were accumulated in 30% of the papers, while 60% of the coauthors appeared in 40% of the papers. We find that predicting the citation number from the coauthor number can be more reliable than predicting the coauthor number from the citation number. For both citation distribution and coauthor distribution, the standard deviation is larger than the average value. We caution the use of such an unrepresentative average value. The average value can be biased significantly by extreme minority, and might not reflect the majority.     

Classic articles on social work field in Social Science Citation Index: a bibliometric analysis

This study aimed to identify and analyze characteristics of classic articles published in the Web of Science social work subject category from 1856 to 2011. Articles that have been cited at least 50 times were assessed regarding publication outputs, distribution of outputs in journals, publications of authors, institutions, countries as well as citation life cycles of articles with the highest total citations since its publication up to 2011 and the highest citations in 2011. Five bibliometric indicators were used to evaluate source countries, institutions, and authors. Results showed that 721 of the most highly referenced articles, published between 1957 and 2008, had been cited at least 50 times. Child Abuse & Neglect and American Journal of Community Psychology published the most classic articles. USA produced 89 % of classic articles and also published the most number of single, internationally collaborative, first author, and corresponding author classic articles. The top 38 productive institutions were all located in the US. The University of Illinois was the most productive institution for the total classic articles while University of California, Los Angeles produced the most inter-institutionally collaborative articles and Arizona State University published the most single institution articles. Furthermore, a new indicator, Y-index was successfully applied to evaluate publication characteristics of authors and institutions. High percentage of authors had the same numbers of first author and corresponding author status of classic articles in social work field.     

Usage versus citation behaviours in four subject areas

This study puts an emphasis on the disciplinary differences observed for the behaviour of citations and downloads. This was exemplified by studying citations over the last 10 years in four selected fields, namely, arts and humanities, computer science, economics, econometrics, and finance, and oncology. Differences in obsolescence characteristics were studied using synchronic as well as diachronic counts. Furthermore, differences between document types were taken into consideration and correlations between journal impact and journal usage measures were calculated. The number of downloads per document remains almost constant for all four observed areas within the last four years, varying from approximately 180 (oncology) to 300 (economics). The percentage of downloaded documents is higher than 90 % for all areas. The number of citations per document ranges from one (arts and humanities) to three (oncology). The percentages of cited documents range from 40 to 56 %. According to our study, 50–140 downloads correspond to one citation. A differentiation according to document type reveals further download- and citation-specific characteristics for the observed subject areas. This study points to the fact that citations can only measure the impact in the ‘publish or perish’ community; however, this approach is neither applicable to the whole scientific community nor to society in general. Downloads may not be a perfect proxy to estimate the overall usage. Nevertheless, they measure at least the intention to use the downloaded material, which is invaluable information in order to better understand publication and communication processes. Usage metrics should consider the unique nature of downloads and ought to reflect their intrinsic differences from citations.