Research Impact

While there are now several metrics that purport to measure a journal's impact, the oldest (and arguably most controversial) is the impact factor.

A journal's impact factor is a ratio that incorporates 3 years' worth of citation data:

It is worth noting that the citable articles in the denominator refer to "substantive, scholarly articles." Such materials are categorized in Web of Science (WoS) as one of three document types: Article, Review, or Proceedings Paper. This does not encompass everything that a journal publishes; for example, editorials and letters are excluded from the denominator's number of citable items, even though such materials are counted in the numerator's total number of citations.

Here are some ways journal impact factors can be useful to researchers:

• as one criterion for selecting journals to submit an article to
• as an indicator of a journal's prestige, quality, reputation, and/or influence within its field

Be aware that there are many criticisms and controversies surrounding the use of impact factors. Here are just a few of them:

• lack of transparency in how impact factors are calculated
• citation counts are not accurate proxies for influence or impact
• an impact factor cannot tell you anything about an individual article or its citation rate
• impact factors are imprecise: 
  • they do not count books that cite journal articles
  • they also do not count citations from materials published in journals that are not included in Journal Citation Reports (JCR)/WoS
• a journal's impact factor cannot tell you anything about the merit, usefulness, applications, or quality of a researcher's work
• impact factors can be gamed/manipulated by researchers, publishers, and journal editors
• disparate impact:
  • fields with literature that grows/advances quickly (i.e., molecular biology) will have journals with higher impact factors than fields with literature that is more durable (i.e., mathematics, anatomy)
  • the time between initial submission and publication of an article differs across disciplines, and this difference affects a journal's impact factor
  • different fields have different citation and authorship cultures/practices: in some fields, articles include many citations whereas in others, the list of references is much shorter; similarly, in some fields publications have many co-authors while this is not standard practice in other fields
  • coverage in JCR/WoS is greater for the natural/physical sciences and less so for the arts, humanities, and social sciences

In addition to impact factor, a journal's acceptance rate is another criterion researchers sometimes consult when researching journals to submit an article to. You can find information about journals' acceptance rates through Cabell's Directory of Publishing Opportunities.

Acceptance rate for the journal American Economic Review, as presented in Cabell's Directory of Publishing Opportunities, which ranges from 6 - 10%.