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Research Impact: More Research Impact Metrics

Introduction

A number of other metrics should be taken into consideration to objectively and comprehensively evaluate a researcher’s profile, such as journal’s impact factor, Source Normalized Impact per Paper (SNIP), Impact per Paper, etc. Below are some examples. 

Journal Impact Factor and More

A.   Journal Impact Factor (from Journal Citation Reports, Web of Science)‚Äč

Journal Impact Factor (JIF) is a common used metric to evaluate journals via Journal Citation Reports (JCR), which is based on Web of Science database. It provides a functional approximation of the mean citation rate per citable item. If Journal A has an impact factor of 5, on average, the articles published in Journal A within the last 2 years have been cited 5 times. As such, a journal would aim to work towards as high an impact factor as they could.

Even though impact factor has been commonly used to evaluate journals, it also has a few cons, for example, it does not account for positive or negative citation, it is bound to the contents of the Web of Science database only.
 
a) How to find a Journal’s Impact Factor (JIF) in JCR

To find a journal’s impact factor in JCR, you can follow the few steps below:
  i) When you are in the Journal Citation Reports database page, search a journal by keying in the journal title as shown in Fig. 1
  ii) You will get the journal’s citation report as shown in Fig. 2 below. You can see how the JIF was calculated as highlighted in the red box.
  iii) Or you can click “Browse by Journal” to get the list of journal titles ranked by Journal Impact Factor as shown in Fig. 3, with each journal’s Impact Factor and Eigenfactor Score presented in the red box below.
  iv) Click on the individual title to view the journal citation report including other influence metrics such as Article Influence Score and Normalized Eigenfactor as shown in Fig. 4.
b) Relative analysis of JIF in a discipline

There is a common argument that choosing a journal solely based on its JIF is not the best strategy. In some core subjects, where the number of researchers is low, JIF will also be low. It is therefore more useful when evaluating journals within the same discipline; impact factors of journals should not be compared across different disciplines. To do a relative analysis of JIF in a special subject area, you can do it using JCR as below::
  i) From JCR homepage, select to “browse by category”, the “Category Ranking” page is shown in Fig. 5, all journal categories are ranked by number of journals. You can select a specific category by following steps 1, 2 and 3. The result will be shown in Fig. 6.
  ii) In the specific category page, you will get a few indicators of this category, such as the median impact factor and the aggregate impact factor. You can click the category name to see the details.
  iii) In the individual category page as in Fig. 7, you will see the number of journals under the “Cell Biology” category by year, and other indicators such as median impact factor by year, which will help you understand the “middle” impact factor of indexed journals in this field in this year. You can use this indicator to orient your selected journal in relation to the field.
  iv) Clicking on the number under “# Journals” will bring you to the list of journals under this category in a specific year as shown in Fig. 8. The list will also show the individual Journal Impact Factor, for example, the journal Cancer Cell’s JIF is 23.916 as highlighted in the box. Comparing with the median impact factor of 3.485 in this category, you will be able to tell where your targeted journal is in this field, and whether it is suitable for your paper or not. Or you can also use the list to shortlist the journals you want to send your paper to. To know more about this journal, you can click the journal title to view the full journal profile.

B.   Source Normalized Impact per Paper (SNIP)

Source Normalized Impact per Paper (SNIP) measures the contextual citation impact of a journal by weighting the citations based on the total number of citations in a discipline. This method normalized for differences in citation practices between disciplines, so that a single citation is given greater value where citations are less frequent in that field.

Click here to find a title’s SNIP calculation via Scopus.

To find a list of journal titles’ SNIP calculation via Leiden University’s CWTS Journal Indicators, refer to the figure below.


C.   Impact per Paper (IPP)

Measures the ratio of citations to citable items for a given journal over a given period of time. IPP is the most direct correlate to the Impact Factor, but it calculates this ration over three years rather than two and it includes only peer-reviewed scholarly papers in both the numerator and the denominator. IPP is the foundational metric for the SNIP; it was previously known as RIP (raw impact per publication).

To find a list of journal titles’ IPP calculation via Leiden University’s CWTS Journal Indicators, refer to the figure below.