At what score can a journal be considered a top journal in any discipline?
A journal’s quality score is a key factor that almost all research scientists take into consideration when choosing to submit their paper to a journal. The perceived quality of a journal is important for a variety of reasons, including, for example, what other scientists think about the impact or quality of your research, what grant funding agencies think about the quality of your research, and how highly your institution rates the quality of your research when evaluating your application for promotion. Therefore, for most scientists, it is a priority to publish in a top journal whenever possible.
What indexes are used to define a top journal?
When it comes to identifying a top journal to submit your manuscript to, there are a number of different metrics you can consider in order to assess journal quality. One of the most commonly used metrics is impact factor (even though its utility is fairly controversial). The impact factor of a journal is calculated by dividing the number of citations that a journal receives in a single year by the number of papers it published in the previous two years. For example, if all articles published by a journal in 2018 and 2019 were collectively cited 1000 times in 2020, and the journal published 500 articles total in 2018 and 2019, the journal would have an impact factor of 2.
Another common journal quality metric that is gaining in popularity is the h-index. First proposed in 2005, the h-index is calculated by identifying the number of papers published by a journal (n) that have been cited at least n times. For example, if 25 articles published by a journal were cited at least 25 times, then the h-index score of the journal would be 25.
As there are a number of different quality indexes that can be used to evaluate a journal, the definition of a top journal will vary depending on the index that is used. Typically, the scores from different indexes will give a relatively consistent picture of the quality of the journal, but it is important to be aware of the distinctions to have a clear idea of how a top journal is defined.
What score indicates a top journal?
Generally speaking, to determine which journals in your field are considered top journals, you should look at the distribution of scores for all journals in the field (whether by impact factor, h-index, or some other metric). This will give you an idea of how the journals within a field compare to one another.
SCI Journal analysed the impact factors of 13,000 journals across 27 scientific disciplines and graphed the results to help identify the impact factor range that defines a top journal. They found that about one quarter of journals have an impact factor of less than 1, suggesting that these are lower-tier journals. Interestingly, despite the large number of journals with an impact factor greater than 1, less than 2% have an impact factor that is over 10, making this a very select subset of journals. This analysis argues that, in general, a scientific journal with an impact factor greater than 10 could be considered a top journal in most fields.
Another way to identify top journals is by looking at h-index rankings, which are easy to compare using the Google Scholar h-index ranking tool. This list ranks all scientific journals by h-index in descending order, so is less useful for identifying a top journal in a specific field, but still yields an intriguing insight into the scientific publishing field as a whole. Based on this list, the top journals overall, as ranked by h-index, tend to be those with a very broad scientific scope, rather than more specialised journals. These top journals include well-known and perhaps obvious titles such as Nature, Science and Cell.
One of the most highly ranked top journals according to h-index is the New England Journal of Medicine, which focuses exclusively on medicine, making it one of the fewer more specialised journals in this upper echelon. Multiple chemistry journals are also near the top of this list, suggesting that top journals in the field of chemistry have higher quality scores than top journals in other scientific fields.
SCImago is another well-known journal ranking system that can be consulted to identify a top journal in your field. In addition to reporting h-index scores, the SCImago journal ranking system also assigns a score known as the SCImago Journal Rank indicator (SJR). Based on the SJR, journals are divided into quartiles per discipline. Top journals are generally considered to be those in the upper quartile (Q1) of SJR scores. Using the SCImago journal ranking tool, you can compare journals within a comprehensive list of professional scientific journals or narrow your search down to a specific field or discipline.
Using this option provides useful insight into what score indicates a top journal for specific scientific disciplines. For example, the top journal in the field of physics is Reviews of Modern Physics, with an SJR score of 21.9 and an h-index of 316, while the top chemistry journal is Chemical Reviews, with an SJR score of 20.8 and an h-index of 656. This comparison shows that, while the top physics and chemistry journals are ranked similarly based on SJR score, the h-indexes are fairly different; so it is important to know how you define a top journal before choosing a journal to submit to.
Another interesting example is Nature, which, as mentioned above, has one of the highest h-index values of all scientific research journals, at 1159. Interestingly, however, its SJR score within the category of ‘multidisciplinary’ journals is only 14.0, which is noticeably lower than the SJR scores of the top physics and chemistry journals. Again, this demonstrates the importance of carefully selecting the metric you or your institution uses to define a top journal for your field.
If you’re still struggling to identify a top journal in your field, we recommend consulting the Web of Science, which maintains a curated list of journals that are carefully evaluated for quality and impact. Searching for a specific field or journal title within this database can provide a wealth of information about which journals are considered top journals in your field and could be an appropriate target for your next submission.
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