Bibliometrics is a statistical number obtained after a biomedical publication. It is a score that is given to a medical paper which reflects the impact of the research in science. It can also be used for medical books, websites, conference proceedings and policy documents. In simple terms, it is a measure of the impact of research [1]. It is traditionally used by librarians and currently researchers use it for:

  • Providing evidence of the impact of their research output in their curriculum vitae when applying for jobs, promotion or research funding

  • Investigating new or emerging areas of research

  • Finding potential research collaborators

  • Choosing in which journals to publish their research

1 What Are the Various Bibliometric Scores?

Traditionally, the academic success of a doctor was determined by the number of papers he or she published in any journal and this was later changed to papers published in peer-reviewed journals. As academia progressed there was a need to have a yardstick so that rather than only quantity, the quality of the papers became important. This led to the use of certain scores like the impact factor and h-index. However, with the widespread use of social media, new generation scores have evolved. There are now more than two dozen bibliometric scores available. These scores can be classified into two broad categories (Fig. 34.1):

  1. 1.

    Classical or traditional scores—These are based on the number of citations each article gets and are well known to the majority of us. Examples are of this are the Impact factor of a journal, the H-index and citation score

  2. 2.

    Alternative metrics—With medical research increasing many new metrics like SCImago (SJR), the Eigenfactor score (ES), the source-normalized impact per paper (SNIP) called simple metrics or hybrid metrics such as Altmetrics and Plum analytics have evolved. These take into consideration newer factors like the number of downloads, social media mentions and post-publication reviews. These scores have their own strength and limitations and will be discussed later [2]

Fig. 34.1
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Various bibliometric scores

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2 What Does Citation Mean?

Citation is the bibliographic acknowledgment of a previously published article [3]. The number of times an article has been quoted is its citation index [4]. In other words, the index is a process that allows us to track the use of an idea by other authors and is a measure of a paper’s importance.

Citation establishes the informational ‘ancestry’ or ‘hierarchy’ of a particular idea as it is expressed in the literature. This ancestry is to be cited by the author of the current manuscript. For example, if an original paper on the ‘Role of endoscopy in patients with fatty liver’ contains 12 citations, each of these 12 references can work as potentially referable facts to support the text mentioned in any future article.

Careful and accurate citation helps the authors of the original paper gain respect and acknowledgment. It also helps to develop a network between the original and new researchers. Citation indexing has many advantages as it excludes the need for intellectual indexing and overcomes language barriers and is highly effective, reliable and quick [5]. However, according to one survey, approximately 44% of all published papers are never cited. Thus, if you manage even a single citation you are in the top 56% in your field and with 10 or more citations you have reached the top 24% of the most cited works worldwide. If you get 100 citations you are in the top 1.8% [6].

3 How Is the Citation Index Calculated?

The Citation Index counts the number of times an article has been cited by other authors over a certain time period to judge the impact of its publication. The caveat, however, is that there is no single citation site that gathers such information and stores such data on published manuscripts. For a complete analysis of the impact of a manuscript, the authors require help from many different sites which carry this information and include The Web of Science, Scopus and Google Scholar [7].

What Citation Indexing does is to record a ‘heading or title’ for each reference or ‘citation’ that these current authors make in their journal articles and trace it back to each previously published article or book. In short, they keep a database of all the published articles and match them via pre-designed algorithms to locate when a previously published work is mentioned in a new study, as a reference.

4 What Is The Journal Impact Factor?

The journal impact factor is calculated by Clarivate analytics once in three years and depicts the performance of the journal in the previous 2 years.

The impact factor of a journal is a Scientometric índex that measures the intellectual influence of that journal and is calculated from the data of the total number citations achieved by it for papers published in it, in the preceding 2 years. It was initially used by librarians to decide whether or not to purchase a journal but is now used as a tool for judging the quality of a journal since it only uses data from the recent past. Thus, it is often used to rank the relative importance of a journal within its domain; journals with higher impact factors are often deemed to be more important than those with lower ones. The Impact Factor is calculated in any given year, as the frequency of citations, received in that year, of manuscripts published in that journal during the two preceding years, divided by the total number of ‘citable items’ printed in that journal during the 2 preceding years [1, 2, 7, 8].

For example, the 2020 IF for a journal is calculated as follows:

  • a = the number of times articles published in 2018–2019 were cited in indexed journals during 2020

  • b = the number of articles or reviews published in 2018–2019

  • Impact factor = a/b

The articles which are not included in the denominator are editorials, letters to editors, medical news, obituaries, rectification notices and meeting abstracts. Thus, original articles and reviews are the most important for journals in calculating their impact factors.

5 What Are the Limitations of the Impact Factor?

Garfield first proposed the concept of the Impact Factor in 1955 in a paper published in the journal ‘Science’ [9]. Subsequently, Thompson Reuters divided manuscripts into non-citable (editorials, letters to editors, medical news, obituaries, rectification notices, meeting abstracts, biographical items) and citable items. The problems with the impact factor are that when non-citable items are cited, they are counted in the numerator, but excluded from the denominator thus increasing its value. These citations from non-citation papers are called ‘free lunches’ [10, 11]. It was found that the impact factor of the Lancet was reduced by almost 40% when just counting citations of the citable items, and Nature’s Impact factor would be reduced by some 30% by including letters. Thus, the numerators and denominators are important. For calculation of the impact factor and a little change in any one of them can cause substantial variations [12].

The impact factor provides a general understanding of a journal without giving importance to individual articles. Also, journals that are not in English have a low impact factor, especially if the title, abstract and keywords are not in English [13].Many articles have multiple authors and with this, there are chances that if their own work is cited the impact factor will be high [14, 15].

6 What Are the Recommendations of the World Association of Medical Editors (WAME) on the Impact Factor?

The impact factor is broadly viewed by authors and academic institutions as a measure of a journal’s standing and also has usefulness in the authors’ career in academic medicine. However, the impact factor can be pretentious by a number of features unrelated to journal quality, including self-citation by a journal, publication timing, and types of articles published. The following recommendations have been made by the WAME: [16].

  • ‘More research is needed to evaluate the impact factor and other measures of journal and article quality’

  • ‘Journal editors should look beyond the impact factor as a summary statistic and present other indicators of journal visibility, such as circulation, number of published articles, and the distribution of the citations. Such demographics of a journal should be regularly published to inform journal readers and authors’.

  • ‘Journal editors have the responsibility to educate their readers, authors, administrators, and their scientific community in general about the impact factor and its relevance, as well as about other measures of journal and article quality’.

7 What Is Self-citation?

A self-citation is a quotation to a manuscript written by the author earlier which is quoted by him or herself in a fresh manuscript on the same topic.

Although it is not considered unethical to have self-citations, extreme self-citation is unethical. Examples of this are that there are more than one hundred thousand researchers in the world who have self-citations from more than 50% of their own work or citations from their co-authors, with the median self-citation rate being 12.7%. From India, Sundarapandian Vaidyanathan is famous for self-citation. He has received 94% of his citations from himself or his co-authors up to 2017 [17].

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8 What Are the Impact Factors of the Top Indian Journals?

There are many Indian journals some of which are specialty based and others for a general readership. The aim of all these medical journals is to disseminate new scientific knowledge among physicians, clinicians and researchers so as to improve the patient that is imparted. The exact number is not known but an estimate is that there are about two hundred. The impact factor for the top 20 Indian medical journals is given in Table 34.1. Unfortunately, all are rather low.

Table 34.1 Impact Factors of some important Indian Medical Journals
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9 What Are the Impact Factors of Some Important International Medical Journals?

PubMed includes more than thirty thousand journals and PubMed Central has approximately two thousand journals listed in their databases. Every year, several new journals on all medical specialties are being added. Journals are published either by well-established academic institutions and societies or private organizations (Table 34.2).

Table 34.2 Impact factors of the top five international journals
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A manuscript published in a journal with a high impact factor carries great prestige not only for the authors but their departments and institutions as well.

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10 Should We Publish in a Journal with a High Impact Factor?

The impact factor of a journal usually, but not always, reflects the quality of a manuscript and its acceptance among readers [14, 15]. However, it is now so widely used as a guide for academic promotion, etc. that there has been some criticism of its dominance. For instance, the National Health and Medical Research Council an Australia-based research funding agency is against using the impact factor. The San Francisco declaration in 2020 concluded that one should not judge a journal just by looking at its impact factor as it does not reflect the quality of all the papers in the journal. They recommend:

  • Removing the use of journal-based metrics, such as journal Impact Factors, in funding, appointment, and promotion considerations

  • Evaluating research on its own qualities rather than on the basis of the journal in which the research is published

  • Using the opportunities provided by online publication (such as relaxing unnecessary limits on the number of words, figures, and references in articles, and exploring new indicators of significance and impact).

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11 What Is the h-index?

The h-index is also known as the ‘Hirsch index’ and was introduced in 2005. The ‘h-index’ is an author-level metric that attempts to measure both the productivity and citation impact of the publications of a scientist or scholar. It is a more specific method of finding the impact of a scientist using citation analysis which measures not only the quality but also the quantity of his publications. For example, if a researcher has an h-index of 10 it means that he has published at least 10 papers for which they have received at least 10 citations [2, 17].

The h-index for an author is thus a score that measures the productivity and citation impact of the publications by a scientist. An h index of 20 is good, 40 is outstanding and 60 is truly exceptional (Table 34.3).

Table 34.3 Generalizations of the h-index, according to Hirsch
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12 What Are Strengths and Limitations of h-index?

The h-index is easy to calculate. It combines the research output and impact factor [18]. However, it cannot be used as a measure to compare two investigators in different fields of medicine, as there is field-related variation and also citation pattern. The h-index is considered to be a more accurate performance of research than the impact factor. The young investigator has a disadvantage because with time both research output and impact will change with time. The h-index is a better marker as it combines impact factor and research output that the other indices use which depend on a single parameter like the total number of citations or citation per paper. The h-index does not look into various co-authors and gives equal credit to all of them. It excludes poorly cited articles but it does not exclude self-citation. This could lead to an inflated h-score. Senior faculty are likely to have better h-indexes as their research performance will get better with time.

Many versions of the h-index have been used to overcome its limitations. However, none of them are perfect. The G-Index is another marker that considers the citation for top publications of the author; however, it is not widely accepted [2]. The e-index attempts to differentiate between researchers with similar h-indexes [19].

13 In Which Journal Should You Preferably Publish Your Work: Indian Or International?

It is a common tendency for Indian researchers to try and get their work published in international journals rather than in Indian journals because it reaches a wider audience and commands more prestige—even among Indian selection bodies.

This practice demoralizes a researcher because not only is it difficult to get accepted but there is a certain bias against articles from developing countries as generally being of poor quality and not being relevant to the majority of the journal’s readers. Repeated rejections also cause long delays in publication.

However, till the quality of our own journals improves we will have to aspire towards what is best.

14 What Is the Cite Score (CS)?

The cite score is the average number of citations that a biomedical manuscript received over the last 3 years. This score was started by Elsevier Publishers in 2016. In contrast to the impact factor, this score is given to all cited articles including editorials, letters to editors, conference papers and other articles indexed by Scopus. Elsevier believes that the cite score provides a comprehensive, transparent view of the journal [20].

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15 What Is the Scimago Journal Rank (SJR)?

This was developed from the Scopus database by Elsevier. SJR is calculated by.

The Weight value based on the subject field and Quality and Reputation of the journal. This overcomes the problems of specialties that have a smaller number of experts. This score takes into account the citations which an article has received in the last 3 years. It uses an algorithm to handle self-citation and the overall score calculation is complex is open access and available free online at www.scimagojr.com. India is among the top ten countries and the only developing country included if the Scimago Journal Rank (SJR) is used. The average citation parameters are listed in Table 34.4 [2, 21].

Table 34.4 Top ten countries with high Scimago Journal Rank
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16 What Is Eigen factor Metrics?

The Eigenfactor metrics give two scores called Eigenfactor score and article influence score. It calculates the number of times the article has been cited in the last 5 years. It is relatively a new metric and is a paid score. In simple words, Eigenfactor is basically a measure of how many people read the journal and think its contents are important. Eigenfactor also takes into account self-citation. Usually, the Eigenfactor score is combined with other scores [2, 22].

17 What Is Altmetrics?

Altmetrics takes into account the digital attention which an article receives. There is a mechanism to track and prevent self-citation. It can also track repeated posts by the same person. All non-journal sources like social media, Wikipedia, blogs and mainstream news are used. It is represented by a colourful donut (Fig. 34.2). The scores can be checked using the website Altmetric.com. the only drawback of this score is that social attention does not necessarily mean a good quality article. The data coverage started in 2011, older articles are not covered by this score [2, 23].

Fig. 34.2
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Altmetrics donut

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18 What Is the Plum X Metric?

This was founded in 2012 but was acquired by Elsevier in 2017. It is integrated with Scopus PlumX Metrics, providing insights into the ways people interact with individual pieces of research output (articles, conference proceedings, book chapters, and many more) in the online environment. Examples include: when research is mentioned in the news or is tweeted about. Collectively known as PlumX Metrics, these metrics are divided into five categories to help make sense of the huge amounts of data involved and to enable analysis by comparing like with like (Fig. 34.3) [2, 24].

Fig. 34.3
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PlumX Metrics

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19 What Is ORCID?

It is Open Researcher and Contributor’s Identification. It is given at the time of registration and submission of an article online. This helps to track all articles with the same number and also tracks the article’s responses on social media [25].

20 Conclusions

  • Once an article has a PubMed citation it means that it is MEDLINE-indexed, manuscripts deposited in PMC and also in the NCBI Bookshelf.

  • The impact factors of Indian journals are very much lower than those of international journals.

  • The h-index is calculated for the authors’ most cited papers and the number of citations that they have received in other publications.

  • Bibliometric scores are required by universities and other academic institutions for the promotion and also for research funding

  • The newer scores like Eigenfactor score, PageRank index, source normalized impact per paper, plum analytics and Altemetrics are new generation indexes.