Impact Factors and Citation Analysis: Researcher Impact
A guide to bibliometrics, journal impact factors, h-index, altmetrics, etc.
h-index
Yourproductivity as a researcher can be measured by your total number of
articles, and the impact of your research can be measured by the total
number of times your articles have been cited. The h-index (AKA Hirsch index) is a combined measure of both productivity and impact. An index of h means that your h most highly-cited articles have at least h citations each.
The h-index
is more informative than total number of articles (which ignores how
well those articles have been received by other researchers) or total
number of citations (which can be inordinately influenced by a small number of highly-cited articles and therefore not an accurate reflection of productivity).
One caveat
about the h-index is that it correlates with the length of a
researcher's career (i.e., researchers who have been publishing for
longer tend to have higher h-indices). It can also be inflated by
self-citation. In addition, the h-index ignores the order of authorship,
which is very important in some disciplines. Additionally, because
different disciplines have different publishing practices, the h-index should not be used to compare researchers across different disciplines. Average impact scores vary widely from discipline to discipline.
Alternative indices
Some claim that average number of citations per article or total number of citations is just as good a measure as—if not better than—the h-index.
One
of the strengths of the h-index—its insensitivity to highly-cited
papers—could also be considered a weakness. That is, once an article has
a sufficient number of citations to gain inclusion into the h core, additional citations are irrelevant. The g-index, in contrast, weights highly-cited papers more heavily. An index of g means that your g most highly-cited articles together have at least g-squared citations. Your g-index will always be equal to or greater than your h-index.
If
multiple-authored articles are common within your discipline, your
h-index may be relatively high. Your degree of contribution to each
article, however, may be thought to diminish as your number of
co-authors increases. The hi-index (AKA
individual h-index) takes number of co-authors into account. Your
hi-index is equal to your h-index divided by the average number of
authors on the articles in your h core.
If
you published a few highly-cited papers decades ago but are now
inactive, your h-index may be higher than an established researcher who
steadily continues to publish or a promising new researcher who is just
beginning to gain recognition. The hc-index
(AKA contemporary h-index) weights newer articles more heavily than
older articles, so that articles lose their value over time. This allows
a clearer picture of more recent levels of productivity and impact.
If
your have been publishing for decades, your h-index will be higher than
a researcher who has been pusblishing for only a few years. The m-index takes
differences in career length into account, by dividing your h-index by
the number of years that you have been publishing.
Several other alternative indices have also been proposed.
One
of the strengths of the h-index—its insensitivity to highly-cited
papers—could also be considered a weakness. That is, once an article has
a sufficient number of citations to gain inclusion into the h core, additional citations are irrelevant. The g-index, in contrast, weights highly-cited papers more heavily. An index of g means that your g most highly-cited articles together have at least g-squared citations. Your g-index will always be equal to or greater than your h-index.
Ifmultiple-authored articles are common within your discipline, your
h-index may be relatively high. Your degree of contribution to each
article, however, may be thought to diminish as your number of
co-authors increases. The hi-index (AKA
individual h-index) takes number of co-authors into account. Your
hi-index is equal to your h-index divided by the average number of
authors on the articles in your h core.
Ifyou published a few highly-cited papers decades ago but are now
inactive, your h-index may be higher than an established researcher who
steadily continues to publish or a promising new researcher who is just
beginning to gain recognition. The hc-index
(AKA contemporary h-index) weights newer articles more heavily than
older articles, so that articles lose their value over time. This allows
a clearer picture of more recent levels of productivity and impact.
If
your have been publishing for decades, your h-index will be higher than
a researcher who has been pusblishing for only a few years. The m-index takes
differences in career length into account, by dividing your h-index by
the number of years that you have been publishing.
Several other alternative indices have also been proposed.
Measuring impact across the disciplines
Measuring Impact Across the Disciplines: Tools and Strategies for Supporting Faculty
ACRL EBSS Current Topics, December 6, 2012, Susan Ariew, Robin Chin Roemer, Rachel Borchardt
Unique researcher IDs
Due to common researcher names, name changes, cultural
differences in name order, and inconsistent use of middle initials, it
can be difficult to accurately calculate measures of personal impact.
Numeric codes can help identify individual researchers.
ORCID (Open Researcher and Contributor ID)
ResearcherID (Thomson Reuters)
By registering for a unique identifier, you can potentially connect a
diverse array of your scholarly output, including journal articles,
datasets, patents, and online comments.
differences in name order, and inconsistent use of middle initials, it
can be difficult to accurately calculate measures of personal impact.
Numeric codes can help identify individual researchers.
ORCID (Open Researcher and Contributor ID)
ResearcherID (Thomson Reuters)
By registering for a unique identifier, you can potentially connect a
diverse array of your scholarly output, including journal articles,
datasets, patents, and online comments.
Tools for calculating h-index
Google Scholar: To
calculate your h-index and see trends in your impact across time,
create a public or private profile. Unlike other databases, Google
Scholar provides citation information not only for journal articles but
also for conference papers and books.
Publish or Perish: Download
this free software, which uses information from Google Scholar to
calculate h-index and several h-index alternatives. A companion user's
guide, The Publish or Perish Book, is available in the Emory book
stacks.
Scholarometer:
Install this browser (Firefox or Chrome) extension and search for an
author to receive a list of articles, number of citations, h-index, and
h-index alternatives based on information from Google Scholar.
Google Scholar Universal Gadget: Search for an author, and this gadget uses information from Google Scholar to calculate number of citations and h-index.
Web of Science (Emory subscription): Search for an author, then click Create Citation Analysis to calculate h-index and see trends in impact across time.
Scopus (Emory subscription): Search for an author, then select the correct author, select all articles of interest, then click View Citation Overview to calculate number of citations and h-index (full citation information available for articles published in 1996 or after).
Microsoft Academic Search: Search for an author to calculate h-index and see trends in impact across time.
h-index Prediction Tool: Predict what your h-index will be in the future.
NOTE: As these tools use different ways of searching for articles and citations, they tend to provide differing results.
calculate your h-index and see trends in your impact across time,
create a public or private profile. Unlike other databases, Google
Scholar provides citation information not only for journal articles but
also for conference papers and books.
Publish or Perish: Download
this free software, which uses information from Google Scholar to
calculate h-index and several h-index alternatives. A companion user's
guide, The Publish or Perish Book, is available in the Emory book
stacks.
Scholarometer:
Install this browser (Firefox or Chrome) extension and search for an
author to receive a list of articles, number of citations, h-index, and
h-index alternatives based on information from Google Scholar.
Google Scholar Universal Gadget: Search for an author, and this gadget uses information from Google Scholar to calculate number of citations and h-index.
Web of Science (Emory subscription): Search for an author, then click Create Citation Analysis to calculate h-index and see trends in impact across time.
Scopus (Emory subscription): Search for an author, then select the correct author, select all articles of interest, then click View Citation Overview to calculate number of citations and h-index (full citation information available for articles published in 1996 or after).
Microsoft Academic Search: Search for an author to calculate h-index and see trends in impact across time.
h-index Prediction Tool: Predict what your h-index will be in the future.
NOTE: As these tools use different ways of searching for articles and citations, they tend to provide differing results.
Calculating h-index using Web of Science
Calculating h-index using Google Scholar
Researcher Impact - Impact Factors and Citation Analysis - LibGuides at Emory University - Main Library (Woodruff)
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