There are a number of ways to appraise a journal for quality and credibility. One may often see numbers attached to journals or see lists of ranked journals; these numbers and ranks are meant to help a researcher navigate through the potentially hundreds of journals in their field. Journal metrics are not without controversy and should not be solely relied upon to gauge the quality of a journal. However, they are worth understanding. Below are some common measurements.
Quartiles
Lists of journals such as the Sources list maintained by Scopus and the journal rankings list maintained by Scimago display what "quartile" a journal is in. Quartiles divide the entirety of the list into four quarters. If a journal is ranked Q1, that means it is in the first quartile; in other words, it is in the top quarter or top 25% of the list. If a journal is ranked Q4, it is in the fourth quartile and is in the bottom 25% of the list. These rankings are based on several metrics: citations, quality of the journal, etc.
Impact factor
Impact factor measures the frequency with which the average article in a journal has been cited in a particular year. It is now calculated by Clarivate and published via the Web of Science Journal Citation Reports. It is used to measure the importance or rank of a journal by calculating the times its articles are cited.
