Impact Factors, and other measures of scholarly impact

Article-level metrics focus on a single article. The most common metric is citation count--how often it has been cited by other articles. Typically, publisher's websites will provide additional information about how often it has been viewed or downloaded from that site. Some databases also try to include this feature. One newly developed metric is Relative Citation Ratio, developed by the National Institutes of Health to measure and compare citation counts within NIH-funded articles, regardless of the journals in which in the article was published.

Many databases track the number of times a specific article has been cited. However, each of these databases will provide a different number of citations. Each database listed here includes a limited number of journals. Only citations within the journals included in the database are reported.

If you are not required to use a specific database to report citation counts, review the descriptions to find a database that covers your subject area in depth. Also, consider using multiple databases and providing comparative citation counts.

Relative Citation Ratio (RCR) was developed by the National Institutes of Health (NIH) to examine and compare citation activity within articles funded by NIH grants and included in the PubMed database. Because gathering the data to calculate RCR takes time, RCR is available about one fiscal year after the article is published (exceptions are made for highly-cited articles). Typically, if you need to provide an RCR for an NIH grant, iCite is the preferred source, although other databases are calculating the RCR as well.