We usually think of journal growth as a good thing. Growth means you are attracting more manuscripts, more authors, and more attention. But journal growth can have a negative effect on citation performance measures, especially on the Journal Impact Factor (JIF). This blog post explains why.
The JIF is one of many citation indicators that measure the performance of journals. Clarivate Analytics will release 2017 JIF scores as part of its Journal Citations Reports sometime in the middle of June 2018. While the JIF has been the target of scorn by vocal members of the scientific and publishing communities, authors are sensitive to the JIF and other measures of prestige when considering where to submit their manuscripts. A journal moving from first to second place in its field may mean fewer high-quality submissions. This is not just an issue for high JIF subscription journals, however. Joerg Heber, Editor-in-Chief of PLOS ONE noted recently that he witnessed a drop in submissions in several fields after the release of their last JIF.
Why Journal Growth Depresses Journal Impact Factors
The JIF is based on measuring, in any given year, the performance of papers published in the previous two years. The much anticipated 2017 JIF will measure citations received in 2017 to papers published both in 2015 and 2016.
For most journals, in most fields, papers tend to receive fewer citations in their second year of publication compared to their third.
Consequently, if a journal grows, its JIF calculation becomes unbalanced with a larger group of underperforming 2-year old papers and a relatively smaller group of 3-year old papers. The overall result is a decline the JIF score. Conversely, a journal that shrinks can expect an artificial boost in its JIF, all other factors remaining the same.
A Helpful Analogy
Consider a regional track-and-field competition for elementary school children. While this annual event hosts a variety of competitions for students enrolled in grades one through five, we will focus on the 100m dash for second- and third-graders, all of whom compete at a single event.
Now, most parents know that third-graders, on average, are much faster runners than second-graders. This does not mean that every third-grader will run faster than every second-grader. The overall winner of the 100m dash may indeed be a second-grader. Nevertheless, we can expect third-graders, as a cohort, will outcompete second-graders. In most games involving children, age makes a lot of difference.
As a result, if your school has a large cohort of second-graders, you can expect that your school will perform worse than a competing school with a larger cohort of third-graders. This age-performance principle works the same for journal articles as it does for children. If you want to increase team performance, it’s better to stack it with older children.
A Journal Example
Consider the following journal example. The Journal of Steadfast Output publishes 100 papers per year. In 2017, papers published in 2015 (having completed their third year of publication) received a total of 800 citations, or 8 cites per paper. Papers published in 2016 (having completed their second year of publication) received a total of 300 citations, or 3 cites per paper. Overall, the journal received a JIF score of 5.500.
Now, consider a scenario (B) where the journal increased output, doubling its size to 200 papers in 2016. If we assume that quality and citation rates didn’t change, this journal should receive more citations overall; however, its overall performance (its JIF) will drop by 15% to 4.667. This is not a huge drop in either relative or absolute terms; nevertheless, members of its editorial board are likely to notice a drop in submissions as its JIF dips below 5.
In scenario C, we consider how the timing of journal growth affects JIF scores. In 2015, our journal published five issues per year, each composed of 20 papers, for an annual total of 100 papers. In the fourth issue of 2016, the journal doubled output to 40 papers. In the fifth issue, it jumped to 100 papers. While this may seem like unrealistic growth, consider that issue 4 is a special issue with invited papers and issue 5 includes papers presented at the society’s annual meeting held in June. Output fluctuations like this are actually pretty common.
In scenario C, we only changed the timing of output, not total output. In 2016, the journal still published a total of 300 papers. The overall citation rate for each annual cohort also remained the same: 8 cites/paper for 2015 and 3 for 2016. However, by publishing one-third of total output at the end of the year we reduced the JIF of this journal by another 13%. Why so much?
A paper published in the December issue of a journal has aged only 13 months when it has completed its second year of publication. In contrast, a paper published the January issue is 25 months old — almost a year older. Using our school grade analogy, children who are born just before the age cut-off are the youngest in their class, whereas children born just after the cut-off can be nearly a year older. For children and papers alike, age can make a lot of difference on performance in their early years.
Managing Journal Growth
Given that older papers tend to outperform younger papers, publishers and editorial boards that wish to grow their journal should consider growing strategically as not to artificially depress future journal citation scores. By strategically, I mean growth that takes place at, or near the beginning, of each calendar year. Unfortunately, this strategy can be taken to extremes. I have seen an example of a journal that cancelled publication of its December issue altogether in order to publish a double-issue in January. Not surprisingly, this change was met with contempt by some competing journal editors as the purpose for this change was readily apparent.
Nevertheless, editors do have some flexibility for scheduling publication of papers that are commissioned, for example, a special issue on a particular topic or a review series.
The timing of publication needs to be balanced with the aims and production schedule of the journal, as rapid changes in growth can cause chaos for the editorial staff and publisher. More importantly, publication timing needs to respect the needs of authors, many of whom are driven by external pressures — by their colleagues, institutions, and their funders — to publish quickly. The needs and expectations of authors are far more important than attempting to manufacture relatively small changes in JIF scores.
Last, it may be very difficult to manage journal output for an open access journal using an APC model and novelty-free acceptance criteria. For example, the journal Medicine, published by Wolters Kluwer published 30 papers in 2013 before it converted to an OA model in 2014. In 2015, it published nearly 2000 papers and more than 3000 papers in 2016. Its JIF dropped from a high of 5.646 in 2014 to a low of 1.804 in 2016.
In a saturated market of multidisciplinary OA megajournals with nearly identical scopes, editorial structures, and prices, a precipitous JIF drop can drive authors to competing titles. Indeed, megajournals like PLOS ONE and Scientific Reports, appear to be fighting for a limited market of author manuscripts.
For closely contested races, publication timing can mean the difference between winning and placing second.