Citation Searching & Impact Metrics

The h-index is a measure of "citedness" as a proxy for productivity and impact. It is the number of articles h in a group of publications N that have received h or more citations. For example, an h-index of 20 means that there are 20 items in the selected group N that have received 20 or more citations. It is like a median, and useful because it discounts the disproportionate weight of highly cited and uncited papers that would skew a mean.

However, the h-index is not an absolute number and will vary considerably depending on several factors.  For example, different databases (e.g. Web of Science vs Google Scholar) cover different segments of the literature and use different methods to count citations. 

Comparing h-indexes:  An author's number of publications and the length of time they've been active affects the h-index.  Older and more prolific authors will usually have higher h-indexes than younger or less prolific authors. If you want to compare your h-index to someone else's, you need to use the same methodology to calculate them and then normalize the values by dividing them by a second factor, e.g. years since PhD. The standard caveats apply when using h-indexes in personnel and funding decisions.

Web of Science is generally considered to be best at capturing metrics from quality sources only due to its selective indexing of largely "high influence" journals and proceedings - meaning that it represents what is typically considered to be the most robust and highest quality publications (though any potential authors should do their own analysis of a journal's quality before publishing in it instead of trusting that because it has made it into one of these indexes it is certainly reputable). This means that it can miss some publications which do not fit in its scope. This can be things like less well known journals - either because they are very niche or due to newness - as well as nonstandard types of literature such as 'grey literature,' white papers, and other types of writings not published in traditional high impact journals. It also does not index as many books as the other options (google scholar indexes the most). As a result, it is considered more robust for STEM fields than for arts, humanities, and social sciences because many of the latter groups' fields use more non-journal publications in determining impact metrics - though it can still be useful for those fields, so long as it is used with the knowledge of what might be excluded from the metrics. 

Things to note when performing an author search in Web of Science:

• It excludes publications that are not in WOS-covered source journals (such as conference papers, book chapters, patents, etc.).
• It may be difficult to distinguish among authors with the same surname/initial(s), so it may include stray hits - especially if the author profile has been auto-generated and not claimed and managed by the author themself.
• It relies on the articles' derived "Times Cited" values, which may undercount your total actual citations.

How to perform an author search:

• Connect to Web of Science (and make sure you're searching the "Core Collection").
• Either start a search for an author right away (last name first, first name second) and click the name of the correct author from one of the publications in the search results, or navigate to Advanced Search and select the Researchers tab. From there, you can search for researchers by name, author identifiers, or organization. 

• Once you click on an author's profile, a list of publications from the Web of Science databases is displayed, in reverse chronological order.  Citation metrics are shown alongside.
• From the Results Set view, you can click on View Citation Report. The Citation Report ranks the articles in descending order of citations received, and provides a year-by-year summary of citations, a sum of Times Cited, an average citations-per-article figure, an option to remove publications, and the h-index for this set of articles. To increase accuracy, browse the entire report, and mark and remove any entries that don't belong there.
• You can export the Citation Report as an Excel or text file.

Scopus is a product of Elsevier, and like Web of Science, is a curated index - all journals and publishers selected to be indexed are chosen by an independent content selection and advisory board. It is similar in size to Web of Science, though it collects significantly more books. 

Things to note when performing an author search in Scopus: 

• owned by Elsevier (a major publisher), so may not be neutral in coverage decisions 
• covers more arts, humanities, and social sciences than Web of Science, but still less than Google Scholar (which has more citations per publication / author across fields at the expense of overall quality of citations due to the inclusive nature of what google includes in its index)
• Recent research* shows that there are significantly more errors in Scopus relating to author affiliations and location than in Web of Science, so that is something to keep in mind when exporting metrics and analyzing trends using Scopus data. 

How to perform an author search: 

1. After signing in to scopus, navigate to the Author Search tab in the search bar - you can search by author name, ORCID, or by keyword (relating to topic or field - tends to be more useful when you can get fairly specific or niche)
2. Select the correct author profile to view a list of their publications and citation metric information
3. You can choose to View All References or the Citation Overview to export publication data for that author. 

Google Scholar has the largest index of the three, and indexes the widest range of types of publications - including preprints, proceedings, white papers, some grey literature sources, everything found in google books, and more. Because of this, google scholar metrics will have more citations and links between types of publications across subject areas - but it comes with some caveats as well. 

Citation metrics are only as reliable as the underlying data. Google Scholar's metrics are generally not reproducible and will differ - sometimes significantly - from data found in Web of Science. Google indexes a different, wider (and largely unknowable) universe of publications. It is also very difficult to resolve author name ambiguity.

Depending on the type of citation information you need, google scholar can be an excellent choice - but be sure to be aware of the downsides as well! 

Things to note when performing an author search in Google Scholar: 

• due to the more inclusive nature of Google Scholar's index, not all citations will be 'quality' citations - some will come from sources that other indexers would not consider (such as non-peer reviewed sources), making citation metrics appear higher than many institutions and publishers would consider accurate
• exporting citations and records can be a headache - there is no mass export option and much has to be done by copy/paste of individual records
• searching for authors with common names can be difficult to parse - especially when authors have not created a profile

How to perform an author search: 

• Search the author by name and select their profile
  • if the author has not created a profile with google scholar, then you will not be able to see the same profile and metrics view, and you would need to perform a search for their name and manually count their publications (citation numbers for each publication will be viewable under each publication link) to determine their h-index 
• From the profile page, you should be able to see a list of their publications, as well as citation metrics, including an h-index and an i10-index (a Google Scholar developed metric which is the number of publications with at least 10 citations)