Evaluating Information Sources: Impact Factors and Citation Counts

According to Journal Citation Reports (JCR), an impact factor is a ratio focusing on original research. 

Impact factor = # of citations to all items published in that journal in the past two years
(divided by)
# of articles and reviews published over those past two years referencing those citations

For example, if a journal has an impact factor of 2.5, this means in the indexed year each article published was cited on average 2.5 times in the previous two years in that journal.

Impact factor is used for journals only.

JCR only includes 12,000 journals and conference proceedings from over 3,300 publishers.

Metrics on the Web

Research Guides 

The most common metric to track an author's impact is ask how often they are cited. However, for the information to be accurate, a database must:

• Have access to all articles an author publishes
• Have the full text of all articles (letters dissertations, etc.) in the author's field and be able to read every reference (citing article) in every article

We may be able to get close, but

• ​Web of Science searches only 10,000 "high impact" journals of the over 24,000 journals in their database
• Google Scholar searches for everything it can find freely on the web
• Specialized databases have limited access to journals (e.g., PsycINFO includes only 2,395 journals)
• The indexed database, PubMed, has citations from over 35,000 journals - but no references

Thus, no one database can give an accurate count of how many times an individual article (much less the author) has been cited! 

The h-index attempts to measure both the productivity and impact of an author. H is the number of articles published by an author which have each been cited at least h times.  (E.g., an author published 4 papers that are cited 10, 6 ,5 and 2 times respectively; that author's h-index is 3.)

Recently, some databases (e.g. Google Scholar) use an h-index for the journal. In this case, h is the number of articles published that have been cited h times over a given time period (H5 = five years).

For more information, see: 

Other options for finding and/or creating author h-index lists.

Google Scholar -

• Create in personal My Profile. Google then searches the web for a matching name. Add and subtract materials. The h-index is  publich and available only for those authors who have created profiles.

Scopus

• Use the author search to select an author

Web of Science

• Use the author search to select an author
• See the box to the right for details

In Web of Science, a report of the author's overall citation counts, h-index, and publications can be created. This will be limited to those citations that are available through Web of Science. (For Scopus and Google Scholar h-index option, see below.)

Step 1: Identify author citations in Web of Science

1. Click +More on the Basic Search line, then on Author Search 
2. Enter the authors Last Name and first initial; Use + Add Author Name Variant to select specific variants; For multiple initials, initials or variants, the * can be used as a wildcard to find all of them
3. Optionally, limit the search using Research Domain and/to one or more Organizations 
4. Click Finish Search 

Step 2: Verify publications

Review the results. If all author citations (and only those author’s citations) have been retrieved, go to Step 4. Use the Marked List function to create a comprehensive list of publications for an individual author.

1. From the search results, select individual items or all items on a page, then click Add to Marked List; Repeat until all items have been reviewed
2. Save the Marked List by registering for an individual account with Web of Science 

Step 3: Find and add missing publications to the Marked List

• If Research Domain or Organization limits were used, use different options or try the search without limits
• Search with the full name of the author: Use the All Databases option from the Select a database drop-down menu 
• Search for individual known citations using: Author, Title and Publication Name 
• From a known citation, click on the link to the author's name

Step 4: Run the Citation Report

Once you have search results that represent all available citations for an author, run the citation report. Note: If you used it, click Marked List and scroll down.

Click Create Citation Report   

Export the report to an Excel file using the Export Data function. Unless all items are specified, only the citations on the web-page (default of 10) will be saved.

In addition to the selected citations, the report will include two charts (Total publications by year and Sum of times cited per year) and the numbers for: Results found (citations), Sum of the times cited, Average citations per item, and h-index.

Note: A researcher has an index of h if h of their papers have been cited at least h times each.

For full instructions, download: