Introduction to Research Metrics
What are research metrics?
Research metrics are the formalized measurements of the performance of journals, articles, or researchers. There are several different methods and variations of research metrics that are commonly used including impact factor, h-index, and altmetrics. Most research metrics calculate a score relying on citation measurements. Altmetrics relies on calculating a score using additional measurements including online and social media activity.
A quick note about research metrics. You may find variations for the same metric vary between the sources used to calculate a score. For example, you might find that you have a different h-index score from Scopus than you do from Google. This is normal, it occurs as a result of the different journals and articles each source uses to determine citation counts. Which should measurement should you use? Each of the resources discussed here are reliable sources of information, you can use the source that most favorably represents your work.
In this guide you will find information about the following research metrics: impact factor, Eigenfactor, h-index, g-index, and altmetrics.
Impact Factor
What is impact factor? The impact factor, also commonly referred to as the journal impact factor, is a measurement of the average number of citations received by a specific journal.
What is it used to measure? An impact factor is used to measure the research at the journal level.
How is it determined? To calculate an impact factor, take the total number of citations a journal has received in the past two years and divide that by the total number of citable articles published by that journal in the past two years.
Where can I find an impact factor for a journal? Journal Citation Reports through Web of Science
Eigenfactor
What is Eigenfactor? The Eigenfactor is similar to the journal impact factor in that it measures the research impact of a journal by measuring the number of citations received. Eigenfactor also takes into consideration where the articles from a specific journal are being cited, giving additional weight to journals that are cited by higher ranked journals as compared to lower ranked journals. This is designed to address concerns over frequent self-citing.
What is it used to measure? An Eigenfactor is deigned to measure research at the journal level.
How is it determined? The formula used to calculate an Eigenfactor is complex, you can see their methods here: Eigenfactor Score and Article Influence Score Detailed methods. Eigenfactor.org relies on Journal Citation Reports for their source data and an Eigenfactor takes five years of citation information into consideration.
Where can I find an Eigenfactor for a journal? Eigenfactors can be found through Eigenfactor.org, which is freely available and sponsored by the University of Washington.
h-index (or h5-index)
What is h-index? An h-index (Hirsch index) is used to measure research productivity of a researcher. It takes both the production level, number of articles, and the citation activity, how frequently the researcher’s work is cited, into consideration. An h5-index is an h-index score that factors only the past five years of publication activity.
What is it used to measure? The h-index was designed to measure the research activity of an author. It can also be applied to a journal or group of researchers (department or institution level).
How is it determined? An h-index is a calculation of both the total number of scholarly publications and the number of times those publications were cited. To determine an h-index, count the number of articles authored by a researcher that have been cited the same number of times. An h5-index is calculated the same way but limited to the last five years.
Where can I find an impact factor for a journal? There are a few resources that can be used to locate an h-index. It is available through author profiles on Web of Science, author details on Scopus, or through Google Scholar where you can create a collection of citations to get a corresponding h-index.
g-index
What is g-index? The g-index score was developed as an alternative to the h-index score. It differs from h-index by accounting for the average number of citations received on publications.
What is it used to measure? An alternative to h-index, g-index is designed to measure the research activity at the author level. It can also be used to measure a group of researchers.
How is it determined? The g-index of a researcher can be calculated by determining the largest number of articles that have an average number of citations equal to that number of articles.
Where can I find an impact factor for a journal? Harzing.com offers Publish or Perish, citation analysis software that can be used to determine the g-index for a collection of articles.
Altmetrics
What are altmetrics? Altmetrics (a portmanteau of alternative and metrics) is a measurement of research that uses sources of information beyond citation counts that traditional metrics rely on to calculate a score. This information comes from several sources including government reports, popular news information (print and online), Wikipedia citations, social media activity, blogs, and patent records.
What is it used to measure? Altmetrics are used to measure research at the article level. By grouping collections of articles together, it can be used to measure the impact of a researcher or group of researchers.
How is it determined? There is no official standard for what should be included in a calculation of altmetrics or how different sources should be weighted. Click here to see a description of how Altmetric calculates their altmetric scores.
Where can I find an impact factor for a journal? Two popular resources for determining an altmetrics score are Altmetric and PlumX Metrics available through Scopus.
iCite
iCite is a free online tool offered by the National Institutes of Health (NIH) that can be used to conduct bibliometric analysis of articles available through PubMed. The iCite suite of tools offers three modules:
Influence module – Can be used to determine the Relative Citation Ratio, which weights article citations for field and time, for an article or collection of articles.
Translation module – Measures when an article’s focus is on Human, Animal, Or Molecular/Cellular. It can be used to calculate an Approximate Potential to Translate, a predication of how likely a paper it to be cited in future clinical trials articles.
Open Citations – Offers link-level usage data from the NIH’s Open Citation Collection.
Use a list of PMIDs or a PubMed search strategy to run analysis
Dimensions
Dimensions is a database that links data from multiple sources allowing researchers to better understand how their research impact in different sectors relate to each other. Dimensions includes data from multiple content types: publications, altmetric, datasets, grants, clinical trials, policy documents, and patents.
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