Research metrics attempt to quantify the scholarly impact of a journal, article, or researcher. You can use research metrics to:
However, keep in mind that research metrics aren't perfect, and they don't necessarily measure quality. Additionally, metrics don't always translate across different disciplines' publication and citation practices, so they can't be compared well across fields. See the San Francisco Declaration on Research Assessment for more information.
This page reviews two commonly used traditional metrics, the Journal Impact Factor and the h-index. See this guide's other page for information on alternative metrics.
The h-index is the maximum value of h, where a given author has published at least h papers that have been cited at least h times.
What It Means
If you have an h-index of 6, you have published 6 papers that have been cited at least 6 times.
The h-index takes time to build. Early-career researchers will almost always have a lower h-index simply because their work hasn't had time to build citations. It's also possible for researchers to inflate their h-index through excessive self-citation.
Find Your h-Index
Multiple databases display h-indexes for authors, including Web of Science and Google Scholar.
Why Do Web of Science / Google Scholar / etc. Show Different h-Indexes?
Because each database calculates its own h-index based off the contents it indexes.
Since Google Scholar is an uncurated database, it will almost always show a higher h-index than curated databases like Web of Science. Some of Google Scholar's extra citations are useful (e.g., more thorough coverage of the grey literature like white papers and preprints), but some of its extra citations come from duplicate records of items and predatory/questionable journals.
A journal impact factor (IF) is the average number of times a paper published in a given journal is cited during a year. IFs are used to estimate the scholarly impact of a journal compared to other journals in its field. It assesses the journal, not individual articles or authors.
What It Means
If a journal as an impact factor of 2.0, recent articles published in that journal have been cited an average of two times.
The impact factor is calculated by adding the total eligible articles a journal published in the previous two years (e.g., 2020 and 2021), then dividing that number by the total number of citations to articles published those years during the year of interest (e.g., 2022).
|Eligible Items Published 2020||81|
|Eligible Items Published 2021||77|
|2022 Citations to Items Published in 2020/2021||216|
Journal X's 2022 impact factor: (81 + 77) / 216 = 1.37
Editorials, letters, news items, book reviews, and corrections are not counted towards a journal's total number of articles published, but citations to these items are counted as citations for calculating the IF.
There are several disadvantages to journal impact factors:
Find a Journal Impact Factor
You can search for specific journals or browse journals by subject in Clarivate Journal Citation Reports.