Peer-reviewed articles are typically written by academic experts, for academic experts in the same discipline. Authors (e.g., researchers) submit a draft article to a journal's editorial team, and the article is then reviewed by several academic experts from the same discipline or area of expertise. These reviewers evaluate the submitted research article and advise the journal's editors on whether the article should be published. Knowing an article has been peer-reviewed gives some assurances that the information in the article is valid and credible.
Learn more about the peer-review process in 3 minutes: Watch "Peer Review in Three Minutes" from NC State University Libraries.
How to tell if an article is peer-reviewed
In Discovery, click the "Peer-Reviewed (Scholarly) Articles" button under the search box on the results page:
This button will filter your results to articles (only articles; no other types of sources) which Discovery has identified as coming from peer-reviewed journals.
Journal impact is a measure of the influence or reputational importance of a journal.
Journal impact is based on a calculation of the number of citations of articles within a journal over a set period of time (often two years) and compares these to other journals in the same subject area or discipline to determine impact ranking. Calculations may consider additional factors, such as the total number of articles published, or how many citations are self-citations. Tools to measure journal impact have differences in terms of calculation methodology or data source for citation counts.
Reliability and limitations of journal impact measurements are also discussed in the literature:
SCImago Journal Rank (SJR)
“The SCImago Journal Rank is a portal that includes the journals and country scientific indicators developed from the information contained in the Scopus® database (Elsevier B.V.).” Scopus contains more than 15,000 journals from over 4,000 international publishers as well as over 1000 open access journals. The SJR measures citations weighted by prestige. It is useful for comparing journals within the same field, and forms the basis of the subject category ranking. Q1 journals are cited more often and by more prestigious journals than those in the other quartiles.
More information on the SJR methodology
SNIP (Source Normalized Impact per Paper)
The SNIP (Source Normalized Impact per Paper) measures citations weighted by the subject field. It is useful for comparing journals not just within the same field but also across disciplines. A SNIP of 1.0 means that a journal’s articles are cited at the average rate for all journals in the same subject area; anything over 1.0 indicates more citations than average in the field while a SNIP of less than 1.0 is below the average. A SNIP of more than 1.5 generally indicates a very well-cited journal.
CWTS Journal Indicators offers a number of bibliometric indicators on scientific journals. These indicators have been calculated based on the Scopus bibliographic database produced by Elsevier.
More information on CWTS Jornal Indicators methodology
CiteScore is a metric for measuring journal impact in Scopus and is based on the average citations received per document. CiteScore calculates the number of citations received by a journal in one year to documents published in the three previous years, divided by the number or documents indexed in Scopus published in those same three years. The CiteScore is useful for comparing journals within the same field, ranking them in subject categories and indicating the percentile they fall into.
More information on CiteScore methodology
Eigenfactor scores are intended to give a measure of how likely a journal is to be used and how frequently an average researcher would access content from that journal.