Are individual scientists now more productive early in their careers than 100 years ago? No, according to a large analysis of publication records released by PLOS ONE today.
Despite concerns of rising “salami slicing” in research papers in line with the “publish or perish” philosophy of academic publishing, the study found that individual early career researchers’ productivity has not increased in the last century. The authors analyzed more than 760,000 papers of all disciplines published by 41,427 authors between 1900 and 2013, cataloged by Thomson Reuters Web of Science.
The authors summarize their conclusions in “Researchers’ individual publication rate has not increased in a century:”
…the widespread belief that pressures to publish are causing the scientific literature to be flooded with salami-sliced, trivial, incomplete, duplicated, plagiarized and false results is likely to be incorrect or at least exaggerated.
To clarify: The authors didn’t measure individual research productivity by the number of papers an early career scientist publishes. Not surprisingly, when looking at papers from scientists in the first fifteen years of their careers, the authors saw that the total number of papers either remained stable or increased for all disciplines throughout the 20th century. But as the number of papers increased, so has the number of co-authors: from none at the start of the century to an average of between two and seven for all fields by 2013 (except the Arts and Humanities).
When taking co-authorship of papers into account — which the authors call “fractional productivity” — the number of papers each researcher has published has not increased, but has actually mostly declined in the last century.
Even when the researchers ignored co-authorship and counted only papers where researchers are first authors — which the authors refer to as “first-author productivity” — the study found no change in productivity throughout the century.
So even if an individual scientist’s CV looks longer today than it did 100 years ago, the amount of published material they’re producing, so to speak, may actually be smaller or the same.
Not everyone is convinced by the findings, however. Ferric Fang from the University of Washington in Seattle — who is also on the board of directors of our parent organization — is one of the skeptics:
Count me among those who continue to believe that “pressures to publish are causing the scientific literature to be flooded with salami-sliced, trivial, incomplete, duplicated, plagiarized and false results.” This new study has done little to persuade me otherwise.
Of course, there are other ways to measure a researcher’s contributions to a paper besides co-authorship. It’s also possible that articles have increased in length across the sample time period, so each co-author may now be responsible for more material than previously.
We also checked for the average length of the paper, and found suggestions that this is in fact getting longer. These data seemed too preliminary to be included in the paper, but independent studies would suggest the same trend. This is important because it further contradicts the salami-slicing hypothesis.
The study’s sample included many different article types — from editorials to correspondence — which often differ considerably in length from research papers. This variety in length may actually support the paper’s outcomes, Fanelli explained:
We included all [article] types, which again makes the results conservative with respect to the hypothesis, because items such as letters or comments are a recent addition to the Web of Science. There is no evidence to suggest that authors were publishing more correspondence in the past than today, and in any case such records are more likely to be missing from past records than recent ones.
The authors explain the rise in co-authorship in the paper, writing:
Co-authorship might also have increased thanks to improvements in long distance communication technology, as well as a growing support for interdisciplinary research. However, the extremely rapid rise in co-authorship observed in biomedical research and other areas suggests that other factors in addition to the growing complexity of science are at play.
When the authors compared papers from different countries, they found the nations that often place higher pressures to publish — such as the United States and the United Kingdom — had higher fractional and first-author productivity. But there is no evidence that authors from these countries are cutting corners to publish more papers, the authors note.
One limitation of the study is that the authors searched for researchers by surname and the first letters of their first and at least two middle names — such as, in the example they provide in the study, “Vleminckx-SGE.” This may skew the results, since women can change their last name, and many scientists don’t have two middle names. Fanelli added:
We focused on those with three initials in their names (first name, and two middle names). This tended to over-represent certain countries, and perhaps has over-represented certain demographics — a referee for example suggested that we are over-representing scientists of catholic background. This however is unlikely to have affected our central results, which concern trends over time that appear to be global.
Even if individual scientists are not producing as much publishable data as before, they still face growing pressures, the study noted, such as writing grant applications, reports, syllabi and other material — all of which may force them to spend less time doing research. Another possible explanation is that the average time and effort that goes into preparing research papers has increased over time.
Cassidy Sugimoto, an information scientist at Indiana University Bloomington, questioned whether a lack of increase in productivity could have any bearing on the unfortunate results of pressure to publish, such as salami-slicing or other questionable research practices:
The main limitation of this piece is implying a link between observed rates of productivity and rates of malpractice…there is no more than a speculative link between [the two].
Fang, in turn, offered some additional evidence that contradicts the study’s findings:
There is simply no denying that most contemporary researchers feel an enormous pressure to publish. For example, a survey of Belgian scientists by Joeri Tijdink and colleagues found that 72% experienced excessive publication pressure, and this pressure was associated with an increase in questionable research practices.
Fang added another important caveat:
The authors have analyzed the average number of papers published by early-stage scientists, but this lumps together both successful and unsuccessful scientists. Since most early-stage scientists do not ultimately pursue an academic career, it would have been preferable to analyze trends in the publication productivity of the most highly productive individual scientists over time.
Moreover, the most “serious flaw” of the study, said Fang, is that it does not account for the fact that last authors of papers, who are the most senior in some disciplines, face the most pressure to publish.
Fanelli, on the other hand, said:
We have no indication that researchers publish more as last authors…But we are obviously still looking at early-career researcher[s]. Properly testing this hypothesis requires a different approach from the one used in this study. It is possible that lab leaders are multiplying their papers by having many junior colleagues, just like, in general, it seems plausible that authors might increase their productivity by salami-slicing their collaborations, so to speak.
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