Scatter and obsolescence of journals cited in theses and dissertations of librarianship

This article analyzes the bibliometric features (the number of pages, completion years, the fields of subject, the number of citations, and their distribution by types of sources and years) of 100 theses and dissertations completed at the Department of Librarianship of Hacettepe University between 1974 and 2002. Almost a quarter (24%) of all dissertations were on university libraries, followed by public libraries (9%). Doctoral dissertations were, on average, twice as long as master's theses and contained 2.5 times more citations. Monographs received more citations (50%) than journal articles did (42%). Recently completed theses and dissertations contained more citations to electronic publications. Fourteen (or 3.2% of all) journal titles (including Türk Kütüphaneciliği, College & Research Libraries, and Journal of the American Society for Information Science) received almost half (48.9%) of all citations. Eighty percent of journal titles were cited infrequently. No correlation was found between the frequency of citations of the most frequently cited journals and their impact factors. Cited journal titles in master's and doctoral theses and dissertations overlapped significantly. Similarly, journal titles cited in dissertations also overlapped significantly with those that were cited in the journal articles published in the professional literature. The distribution of citations to foreign journal titles fit Bradford's Law of Scattering. The mean half-life of all cited sources was 9 years. Sources cited in master's dissertations were relatively more current. Single authorship was the norm in cited resources. Coupled with in-library use data, findings of the present study can be used to identify the core journal titles in librarianship as well as to evaluate the existing library collections to decide which journal titles to keep, discard, or relegate to off-site storage areas.     

A case study of the arbitrariness of the h-index and the highly-cited-publications indicator

The arbitrariness of the h-index becomes evident, when one requires q × h instead of h citations as the threshold for the definition of the index, thus changing the size of the core of the most influential publications of a dataset. I analyze the citation records of 26 physicists in order to determine how much the prefactor q influences the ranking. Likewise, the arbitrariness of the highly-cited-publications indicator is due to the threshold value, given either as an absolute number of citations or as a percentage of highly cited papers. The analysis of the 26 citation records shows that the changes in the rankings in dependence on these thresholds are rather large and comparable with the respective changes for the h-index.     

Double rank analysis for research assessment

Reliable methods for the assessment of research success are still in discussion. One method, which uses the likelihood of publishing very highly cited papers, has been validated in terms of Nobel prizes garnered. However, this method cannot be applied widely because it uses the fraction of publications in the upper tail of citation distribution that follows a power law, which includes a low number of publications in most countries and institutions. To achieve the same purpose without restrictions, we have developed the double rank analysis, in which publications that have a low number of citations are also included. By ranking publications by their number of citations from highest to lowest, publications from institutions or countries have two ranking numbers: one for their internal and another one for world positions; the internal ranking number can be expressed as a function of the world ranking number. In log–log double rank plots, a large number of publications fit a straight line; extrapolation allows estimating the likelihood of publishing the highest cited publication. The straight line derives from a power law behavior of the double rank that occurs because citations follow lognormal distributions with values of μ and σ that vary within narrow limits.     

The influence of missing publications on the Hirsch index

We show that usually the influence on the Hirsch index of missing highly cited articles is much smaller than the number of missing articles. This statement is shown by a combinatorial argument. We further show, by using a continuous power law model, that the influence of missing articles is largest when the total number of publications is small, and non-existing when the number of publications is very large. The same conclusion can be drawn for missing citations. Hence, the h-index is resilient to missing articles and to missing citations.     

How to derive an advantage from the arbitrariness of the g-index

The definition of the g-index is as arbitrary as that of the h-index, because the threshold number g² of citations to the g most cited papers can be modified by a prefactor at one's discretion, thus taking into account more or less of the highly cited publications within a dataset. In a case study I investigate the citation records of 26 physicists and show that the prefactor influences the ranking in terms of the generalized g-index less than for the generalized h-index. I propose specifically a prefactor of 2 for the g-index, because then the resulting values are of the same order of magnitude as for the common h-index. In this way one can avoid the disadvantage of the original g-index, namely that the values are usually substantially larger than for the h-index and thus the precision problem is substantially larger; while the advantages of the g-index over the h-index are kept. Like for the generalized h-index, also for the generalized g-index different prefactors might be more useful for investigations which concentrate only on top scientists with high citation frequencies or on junior researchers with small numbers of citations.     

The hyperlinking pattern of open-access journals in library and information science: A cited citing reference study

Using 17 open-access journals published without interruption between 2000 and 2004 in the field of library and information science, this study compares the pattern of cited/citing hyperlinked references of Web-based scholarly electronic articles under various citation ranges in terms of language, file format, source and top-level domain. While the patterns of cited references were manually examined by counting the live hyperlinked-cited references, the patterns of citing references were examined by using the cited by tag in Google Scholar. The analysis indicates that although language, top-level domain, and file format of citations did not differ significantly for articles under different citation ranges, sources of citation differed significantly for articles in different citation ranges. Articles with fewer citations mostly cite less-scholarly sources such as Web pages, whereas articles with a higher number of citations mostly cite scholarly sources such as journal articles, etc. The findings suggest that 8 out of 17 OA journals in LIS have significant research impact in the scholarly communication process.     

Information sources in library and information science doctoral research

A citation analysis of 61 library science and information science dissertations revealed some interesting publication patterns. About 80% of the citations are to single authors, and as in analyses of periodical literature, males are cited more than females overall (about 61% to 39%). In dissertations related to school or public libraries, the male/female distribution is less disparate; for studies in academic or special libraries two thirds of the authors are male, and male authorship is 75% when only information science dissertations are analyzed. Journal articles are cited more than books, book chapters, proceedings, theses, and other formats with College & Research Libraries and Journal of the American Society for Information Science used most. Library and information science is impacted by several other disciplines, primarily education, computer science, health/medicine, psychology, communications, and business. Authors cited in dissertations represent a somewhat less parochial list in terms of citing U.S. publications than authors cited in studies analyzing journal citations; over half of all works cited were published within the last 10 years.     

Author-team diversity and the impact of scientific publications: Evidence from physics research at a national science lab

In the second half of the 20th century, scientific research in physics, chemistry, and engineering began to focus on the use of large government-funded laboratories. This shift toward so-called big science also brought about a concomitant change in scientific work itself, with a sustained trend toward the use of highly specialized scientific teams, elevating the role of team characteristics on scientific outputs. The actual impact of scientific knowledge is commonly measured by how often peer-reviewed publications are, in turn, cited by other researchers. Therefore, how characteristics such as author team seniority, affiliation diversity, and size affect the overall impact of team publications was examined. Citation information and author demographics were reviewed for 123 articles published in Physical Review Letters from 2004 to 2006 and written by 476 scientists who used the National High Magnetic Field Laboratory's facilities. Correlation analysis indicated that author teams that were more multi-institutional and had homogeneous seniority tended to have more senior scientists. In addition, the analysis suggests that more mixed seniority author teams were likely to be less institutionally dispersed. Quantile regression was used to examine the relationships between author-team characteristics and publication impact. The analysis indicated that both weighted average seniority and average seniority had a negative relationship with the number of citations the publication received. Furthermore, the analysis also showed a positive relationship between first-author seniority and the number of citations, and a negative relationship between the number of authors and the number of citations.     

An index for evaluating journals in a small domestic citation index database whose citation rate is generally very low: A test based on the Korea Citation Index (KCI) database

This study describes the meaning of and the formula for S-index, which is a novel evaluation index based on the number of citations of each article in a particular journal and the rank of the article according to the number of citations. This study compares S-index with Impact Factor (IF), which is the most well-known evaluation index, using the Korea Citation Index data. It is shown that S-index is positively correlated with the number of articles published in a journal. Tapered h-index (h_T-index), which is based on all articles of a journal like S-index, is compared with S-index. It is shown that there is a very strong positive correlation between S-index and h_T-index. Although S-index is similar to h_T-index, S-index has a slightly better differentiating power and ranks the journal with evenly cited articles higher.     

《编辑学报》高被引论文分析

以中国知网<中国学术文献网络出版总库>为统计源,从文献引证的角度分析<编辑学报>高被引论文的分布规律.研究结果表明:该数据库共收录<编辑学报>1989-2009年原文3 508篇,被引文献2545篇,被引率为73%,总被引频次为1万5 863,单篇最高被引频次71;较少的论文拥有较高的被引频次,基本符合"二八定律";前100篇高被引论文中,栏目高被引论文数最多的是<理论研究>(46篇),个人高被引论文数最多的是游苏宁(6篇);前10篇高被引论文每年都在被引用,具有旺盛的生命力.     

Contributing factors to long‐term citation count in marine and freshwater biology articles

Researchers have investigated factors thought to affect the total number of citations in various academic disciplines, and some general trends have emerged. However, there are still limited data for many fields, including aquatic sciences. Using papers published in 2003–2005 (n = 785), we investigated marine and freshwater biology articles to identify factors that may contribute to the probability of citation and for cumulative citation counts over 10 years. We found no relationships with probability of citation; however, we found evidence that for those that were cited at least once, cumulative citations were related to several factors. Articles cited by books received more citations than those never cited by books, which we hypothesized to be indicative of the impact an article may have in the field. We also found that articles first cited within 2 years of publication received more cumulative citations than those first cited after 2 years. We found no evidence that self‐citation (as the first citation) had a significant effect on total citations. Our findings were compared with previous studies in other disciplines, and it was found that aquatic science citation patterns are comparable to fields in science and technology but less so to humanities and social sciences.     

Mapping the literature of health care management: an update

Objective:This study aims to identify the core journals cited in the health care management literature and to determine their coverage in the foremost bibliographic databases used by the discipline.Methods:Using the methodology outlined by the Medical Library Association''s Nursing and Allied Health Resource Section (NAHRS) protocol for “Mapping the Literature of Nursing and Allied Health Professions,” this study updates an earlier study published in 2007. Cited references from articles published in a three-year range (2016–2018) were collected from five health care management journals. Using Bradford''s Law of Scattering, cited journal titles were tabulated and ranked according to the number of times cited. Eleven databases were used to determine coverage of the most highly cited journal titles for all source journals, as well as for a subset of practitioner-oriented journals.Results:The most highly cited sources were journals, followed by government documents, Internet resources, books, and miscellaneous resources. The databases with the most complete coverage of Zone 1 and 2 were Scopus, Web of Science Core Collection, and PubMed, while the worst performing databases were Health Business Elite, ABI/Inform, and Business Source Complete.Conclusions:The literature of health care management has expanded rapidly in the last decade, with cumulative citations increasing by 76.6% and the number of cited journal titles increasing by nearly 70% since the original study. Coverage of the core journals in popular databases remains high, although specialized health care management and business databases did not perform as well as general or biomedical databases.     

An alternative axiomatization of the Hirsch index

We axiomatize the well-known Hirsch index (h-index), which evaluates researcher productivity and impact on a field, and formalize a new axiom called head-independence. Under head-independence, a decrease, to some extent, in the number of citations of “frequently cited papers” has no effect on the index. Together with symmetry and axiom D, head-independence uniquely characterizes the h-index on a certain domain of indices. Some relationships between our axiomatization and those in the literature are also investigated.     

Comparing scientific and technological impact of biomedical research

Traditionally, the number of citations that a scholarly paper receives from other papers is used as the proxy of its scientific impact. Yet citations can come from domains outside the scientific community, and one such example is through patented technologies—paper can be cited by patents, achieving technological impact. While the scientific impact of papers has been extensively studied, the technological aspect remains less known in the literature. Here we aim to fill this gap by presenting a comparative study on how 919 thousand biomedical papers are cited by U.S. patents and by other papers over time. We observe a positive correlation between citations from patents and from papers, but there is little overlap between the two domains in either the most cited papers, or papers with the most delayed recognition. We also find that the two types of citations exhibit distinct temporal variations, with patent citations lagging behind paper citations for a median of 6 years for the majority of papers. Our work contributes to the understanding of the technological impact of papers.     

Cover effects on citations uncovered: Evidence from Nature

We study the effects of an article featured on the cover of the journal Nature on citations to all articles published by its authors. Based on 30 years of bibliometric data, we find that cover articles are cited significantly more than non-cover articles, with this difference being long-lasting. However, when considering all articles (past and future) by Nature authors, we find that the publication of a cover article causes citations to previous articles by its authors to decline relative to citations to articles by non-cover authors.     

The h-index: A case of the tail wagging the dog?

From the way that it was initially defined (Hirsch, 2005), the h-index naturally encourages focus on the most highly cited publications of an author and this in turn has led to (predominantly) a rank-based approach to its investigation. However, Hirsch (2005) and Burrell (2007a) both adopted a frequency-based approach leading to general conjectures regarding the relationship between the h-index and the author's publication and citation rates as well as his/her career length. Here we apply the distributional results of Burrell, 2007a, Burrell, 2013b to three published data sets to show that a good estimate of the h-index can often be obtained knowing only the number of publications and the number of citations. (Exceptions can occur when an author has one or more “outliers” in the upper tail of the citation distribution.) In other words, maybe the main body of the distribution determines the h-index, not the wild wagging of the tail. Furthermore, the simple geometric distribution turns out to be the key.     

A research impact indicator for institutions

This paper introduces a new impact indicator for the research effort of a university, ⁿh₃. The number of documents or the number of citations obtained by an institution are used frequently in international ranking of institutions. However, these are very dependent on the size and this is inducing mergers with the apparent sole goal of improving the research ranking. The alternative is to use the ratio of the two measures, the mean citation rate, that is size independent but it has been shown to fluctuate along the time as a consequence of its dependence on a very small number of documents with an extremely good citation performance. In the last few years, the popularity of the Hirsch index as an indicator of the research performance of individual researchers led to its application to journals and institutions. However, the original aim of this h index of giving a mixed measure of the number of documents published and their impact as measured by the citations collected along the time is totally undesirable for institutions as the overall size may be considered irrelevant for the impact evaluation of research. Furthermore, the h index when applied to institutions tends to retain a very small number of documents making all other research production irrelevant for this indicator. The ⁿh₃ index proposed here is designed to measure solely the impact of research in a way that is independent of the size of the institution and is made relatively stable by making a 20-year estimate of the citations of the documents produced in a single year.     

Characterizing in-text citations in scientific articles: A large-scale analysis

We report characteristics of in-text citations in over five million full text articles from two large databases – the PubMed Central Open Access subset and Elsevier journals – as functions of time, textual progression, and scientific field. The purpose of this study is to understand the characteristics of in-text citations in a detailed way prior to pursuing other studies focused on answering more substantive research questions. As such, we have analyzed in-text citations in several ways and report many findings here. Perhaps most significantly, we find that there are large field-level differences that are reflected in position within the text, citation interval (or reference age), and citation counts of references. In general, the fields of Biomedical and Health Sciences, Life and Earth Sciences, and Physical Sciences and Engineering have similar reference distributions, although they vary in their specifics. The two remaining fields, Mathematics and Computer Science and Social Science and Humanities, have different reference distributions from the other three fields and between themselves. We also show that in all fields the numbers of sentences, references, and in-text mentions per article have increased over time, and that there are field-level and temporal differences in the numbers of in-text mentions per reference. A final finding is that references mentioned only once tend to be much more highly cited than those mentioned multiple times.     

Infectious diseases citation patterns: mapping the literature 2008–2010

Objectives:

The research identified the publication types and ages most frequently cited in the infectious diseases literature and the most commonly cited journals.

Methods:

From 2008–2010, 5,056 articles in 5 infectious diseases journals cited 166,650 items. Two random samples were drawn: one (n = 1,060) from the total set of citations and one (n = 1,060) from the citations to journal articles. For each sample citation, publication type and date, age of cited item, and inclusion of uniform resource locator (URL) were collected. For each item in the cited journal articles sample, journal title, publication date, and age of the cited article were collected. Bradford zones were used for further analysis.

Results:

Journal articles (91%, n = 963) made up the bulk of cited items, followed by miscellaneous items (4.6%, n = 49). Dates of publication for cited items ranged from 1933–2010 (mean = 2001, mode = 2007). Over half (50.2%, n = 483) of cited journal articles were published within the previous 5 years. The journal article citations included 358 unique journal titles.

Discussion:

The citations to current and older publications in a range of disciplines, heavy citation of journals, and citation of miscellaneous and government documents revealed the depth and breadth of resources needed for the study of infectious diseases.

Highlights

• Literature on infectious diseases is multidisciplinary, encompassing medical specialties, public health, and the medical sciences.
• Infectious disease publications cite journal articles more than 90% of the time. Cited journal articles greatly range in age at citation: more than a quarter were over 10 years old.
• Infectious disease citation patterns resemble clinical medicine citation patterns more than public health citation patterns.

Implications

• Infectious disease professionals need access to general medicine titles as well as infectious disease, immunology, virology, microbiology, and public health literature.
• Librarians serving infectious disease researchers and practitioners should provide access to older materials, especially journal back files, to support the cyclical needs of their patrons.