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Research Metrics@HKUL: Journal Level Metrics

Journal Level Metrics

Journal Level Metrics

Journal metrics measure the performance and impact of scholarly journals which allow users to rank or compare journals by making use of citation data. It could be useful for researchers to identify significant journals in a particular field and make their publishing strategies aiming to maximize the reach and influence of their work.

Below is a summary of the commonly used journal metrics:

Provided by Clarivate

Provided by Elsevier

1. Journal Impact Factor (JIF)

2. Journal Citation Indicator (JCI)

1. CiteScore

2. SCImago Journal Rank (SJR)

3. Source Normalized Impact per Paper (SNIP)

Note:

Not all journals are covered in the journal metrics. Only those journals indexed in specific citation databases have corresponding metrics available. In other words, indicators available at Clarivate cover titles indexed in the Web of Science, while those provided by Elsevier cover titles that are indexed in Scopus.

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Clarivate

Journal Impact Factor (JIF)

By Clarivate

 

The Journal Impact Factor (JIF) is a ratio which divides a journal’s received citations by a count of its published articles. It indicates an average citation number for articles from a journal in a particular year and the calculation only covers articles published in a journal in the prior two years. The higher the JIF number, the higher impact the journal is supposed to have.

Let’s take an example of the JIF 2020 calculation:

If the JIF 2020 for a journal is 2.58, it means the citable items published in this journal in 2018 & 2019 have been, on average, cited 2.58 times in 2020.

 

Source: Understanding Journal Citation Reports Metrics (Sep 2021)

 

Pros and Cons

Well-known and simple

JIF is a commonly used metric and well-known to scholars, researchers, and relevant professionals. Its simplicity allows others to understand easily.

However, it is considered that there are deficiencies in the use of JIFs:

Without consideration of research fields

Publishing and citation habits may vary across disciplines. Some research field areas may generally have a lower citation rate compared to other fields, and hence journals in some smaller or less common research fields may have a lower JIF that makes them look disadvantaged.

As a result, it is important to note that comparing JIF across disciplines would not be useful. For instance, the journal ranked first in Infectious Diseases has a JIF of 25.071 in 2020 while the journal ranked first in Sociology only got a JIF of 9.654 in the same year.

Short time span

As only articles published in the preceding two years are included in the JIF calculation, it is considered as a short time period for various disciplines. For some journals, lead time from manuscript submission to publication can last for 2 years. 

Concerns on data manipulation

Since the JIF calculation only takes citation counts into account, there are concerns that it could be possible to intentionally boost citation counts by publishing high amounts of review articles or referencing excessive papers from a journal, as a result, getting a higher number of JIF.

 

Source: Mingers , J., & Leydesdorff , L. (2015). A review of theory and practice in scientometrics . European Journal of Operational
Research, 246(1), 1 19. https://doi.org/10.1016/j.ejor.2015.04.002

 

JIF Quartile & JIF Percentile

Both the JIF Quartile and JIF Percentile indicate ranking of a journal based on the JIF score by comparing it with others in the same JCR subject category. 

JIF Quartile shows a journal’s quartile ranking, whether the journal falls in Q1, Q2, Q3 or Q4. For example, if a journal falls in Q1, that means the journal is performing better than at least 75% of other journals within the same JCR subject category.

JIF Percentile shows a percentile ranking of a journal with a particular JCR subject category. For instance, a journal with a JIF percentile of 91 means that it performs better than 91% of other journals in the same JCR subject category. 

 

Source: Understanding Journal Citation Reports Metrics (Sep 2021)

Journal Citation Indicator (JCI)

By Clarivate

Journal Citation Indicator (JCI) is another impact metric assessing performance of a journal with considerations of categories, publication years, and document type. It is a category-normalized metric calculated for all journals indexed in the Web of Science Core Collection. The metric was first introduced in 2021.

The formation of JCI is the average number of the Category-Normalized Citation Impact (CNCI) of the journal’s articles and reviews published in the prior three-year period.

The average JCI in a subject category is 1. A journal with a JCI of 1.0 means the published papers across the journal received citations equal to the average (mean) for the subject category. If a journal obtained a JCI of 2.0 means it has twice more citation impact than the average in that category.

 

Comparison between JIF and JCI

  JIF JCI
Journal Coverage Not all Web of Science Core Collection journal is included Includes all Web of Science Core Collection journals
Nature of Metric Citation metric Field-normalized citation metric
Time Period for Citation Counts citations made in the current year Counts citations across the whole time period following publication, up to the end of the current year
Time Period for Articles and Reviews Counts items published in the preceding 2 years of the JCR year Counts items published in the preceding 3 years of the JCR year
Early Access (EA) Content from 2020 Onward Included Included
Unlinked Citation Included Not included
Fractional Counting Not included Not included
Citation Sources Coverage Counts all document types from journals, books, and conference proceedings in the WoS Core Collection
Journal Items Coverage Counts the citable items only (articles and reviews)

Source: Introducing the Journal Citation Indicator, A new approach to measure the citation impact of journals in the Web of Science Core Collection (Sep 2021)

Retrieving JIF and JCI of a journal

Both the JIF and JCI can also be retrieved on the journal profile on InCites Journal Citation Reports of Clarivate.

Step 1

Access InCites Journal Citation Reports via Find@HKUL.

Step 2

After HKUL Authentication, enter the name of the journal to perform a search. A drop-down list will appear suggesting journals that may match your search while you are typing. Select the journal title if it matches.

 

Step 3

You will arrive at the profile page of your selected journal. Scroll down to the section “Journal’s performance” and you could view the latest available JIF and JCI of the journal. 

 

Actual JIF calculation can also be viewed by clicking on “View calculation”.

 

An interactive graph for the JCI trend is also available under the indicator. 

 

Extra:

You may also view the JIF of the journal in the past years. By clicking on “View all years” under the graph for JIF Trend, you will be able to view an interactive chart showing the JIF of the journal in the previous JCR years.

 

 

Scrolling down to the “Rank by Journal Impact Factor” section, you could find the JIF Quartile and JIF Percentile of the recent JCR years:

 

Elsevier

CiteScore

By Elsevier

CiteScore calculates the average number of citations received from the year of publication until the end of the calculation window, with a maximum of four years, by the documents published in that journal in the calculation year plus the preceding three years. It is calculated annually and available on Scopus. 

Effective from June 2020, a new CiteScore calculation methodology has been adopted, expanding the citation and publication coverage to a four-year window. An example of the calculation of CiteScore 2020 is appended below:

 

Note: Documents include articles, reviews, conference papers, book chapters and data papers.

The below image shows the coverage in CiteScore:

 

Similar to JIF, CiteScore is also a journal metric measuring average citations to papers published in a journal, but based on the data indexed in Scopus.

On the basis of CiteScore being the core metric, a few metrics are complementary to it, such as CiteScore Percentile, CiteScore Rank, and CiteScore Tracker.

CiteScore Percentile indicates the relative standing of a journal in its subject field, e.g. a journal is in the top 1% of its subject field with a 99th CiteScore Percentile.

CiteScore Rank indicates the absolute standing of a serial in its field, e.g. a journal can be said it is ranked #10 out of 100 journals in the same category.

CiteScore Tracker forecasts the journal’s performance in the coming year, which will be calculated on a monthly basis. 

 

Source: Scopus Content Coverage Guide (Sep 2021); How are CiteScore metrics used in Scopus? (Sep 2021)

SCImago Journal Rank (SJR)

By Elsevier

The SCImago Journal Rank (SJR) measures the prestige of a journal. It expresses the average number of weighted citations received in the selected year by the documents published in the journal in the three preceding years.

Unlike the citation metrics like JIF which counts each citation equally, SJR also takes the source of citations into account on top of the number of citations. It weighs a citation considering the level of prestige of the citing journal, in other words, a citation from a high prestige journal is worth more than those from a journal with lower prestige. The field, quality and reputation of the source journals that the citing article is published in will affect the prestige value.

SJR has an advantage in minimizing the effect from excessive journal self-citation as it limits a maximum of 33% self-citation in its calculation. Its inclusion of the prestige value of a journal and relevant consideration factors made it the most sophisticated indicator in measuring journals’ impact. However, the complexity of its calculation may not be easy to interpret.

 

Source: 

González Pereira, B., Guerrero Bote , V. P., & Moya Anegón , F. (2010). A new approach to the metric of journals’ scientific prestige: The SJR
indicator. Journal of Informetrics , 4(3), 379 391. https://doi.org/10.1016/j.joi.2010.03.002;

Mingers , J., & Leydesdorff , L. (2015). A review of theory and practice in scientometrics . European Journal of Operational
Research, 246(1), 1 19. https://doi.org/10.1016/j.ejor.2015.04.002;

SCImago, (n.d.). SJR — SCImago Journal & Country Rank [Portal]. Retrieved 21 Sep 2021, from http://www.scimagojr.com

 

Retrieving SJR of a journal (via SCImago JCR portal)

SJR is available on Scopus together with other Elsevier’s metrics, i.e. CiteScore and SNIP, but it could also be accessed via a public portal SCImago Journal and Country Rank. The below step shows how the SJR could be retrieved on the portal.

Please read “Retrieving CiteScore, SJR, and SNIP on Scopus” if you would like to obtain it via Scopus.

Step 1

Go to SCImago Journal and Country Rank.

Step 2

Browse journals by clicking on “Journal Rankings”, or search a journal by title, ISSN or publisher name if you would like to view SJR of a particular journal.

 

Step 3

By clicking on “Journal Rankings”, filter the result of the list of journals by selecting different criteria, such as “subject areas”, “subject categories”, “regions / countries”, “types” of publication, and “year”. SJR score and quartile is available next to the journal title.

 

Step 4

SJR in previous years of a journal is available on the journal profile. They are shown in a chart. Other statistical analyses are also available on the same page.

Source Normalized Impact per Paper (SNIP)

By Elsevier

The Source Normalized Impact per Paper (SNIP) is a field normalized metric assessing journal impact. Using data from Scopus, it measures contextual citation impact by weighting citations based on the total number of citations in a subject field. Since SNIP accounts for differences in citation practices between scientific fields, it allows direct comparison of journals in different subject fields.

SNIP is the ratio of a source's average citation count per paper and the citation potential of its subject field. The citation potential of a source's subject field is the average number of references per document citing that source.

 

 

Pros and Cons

SNIP takes both the number of papers and subject field into account during calculation, enabling journal comparison in different fields. However, unlike SJR, SNIP does not consider citation prestige and quality of citations. Its complexity also makes it difficult to check.

 

Source: How is SNIP (Source Normalized Impact per Paper) used in Scopus? (Sep 2021)

Retrieving CiteScore, SJR, and SNIP on Scopus

Step 1

Go to Scopus.

Step 2

After HKUL Authentication, you will arrive the Scopus homepage:

  1. Click on “Sources” 

  2. Select “Title” from the drop down list

  3. Enter the title of the journal and perform a search

  4. Click on the journal title to access its profile

 

 

Step 3

On the journal profile page, the latest CiteScore, SJR and SNIP can be found on the right side.

 

Extra:

When you scroll down, you will also be able to view the journal’s category and CiteScore rank & percentile.