In the last months of 2024, as has been the case for some years now, rankings of the best, most important or most influential scientists are being released. Some lists use the term “most influential”, others, “best”, as well as other adjectives related to quality and excellence. This is because, in any conversation about the importance of researchers, these qualifiers practically merge.
Two rankings recently published by the country's major press (Clarivate and Stanford/Elsevier) showed very different results, despite seeking to measure similar things.
What had the most repercussion in the major newspapers was the list of the “most cited researchers in the world” by the company Clarivate (owner of the Web of Science database and several other services related to the dissemination of information about science and technology). One of the major Brazilian newspapers stated in its main headline that there had been a drop in the number of Brazilian researchers from last year to this year. Note that the list has almost 7 thousand researchers from all over the world. In this list, we would have dropped from 18 to 14 scientists cited in 21 areas of knowledge.
According to the company, this ranking represents the 1% of the most influential authors in the world. To compile the list, the company starts with articles whose indicators are monitored on its Incites analysis platform. After a series of refinements to ensure the accuracy of the information, the list of the most cited authors is created (see the methodology in https://clarivate.com/highly-cited-researchers/evaluation-and-selection/).
The Stanford ranking, produced in partnership with Elsevier (owner of the Scopus database, among other scientific and technological information assets), lists the researchers in the 2% most influential group in the world.
The list is based on a series of article citation metrics (c-score) which initially guides the classification of the most influential in 22 areas and 174 subareas of knowledge (see the methodology in https://top2percentscientists.com/methodology-and-selection-criteria-of-top-2-scientists-list/).
The list, which has a different approach from Clarivate's, is much longer than that, with more than 217 names. This year's ranking includes 1.077 Brazilians.
A quick comparison between the two lists shows important differences, simply because the researchers are not the same from one to the other. Let's see.
Looking at the top 6.886 researchers on Elsevier's list (the same number of names on Clarivate's list), there are seven Brazilians. Of these, only two names are also cited among the 14 on Clarivate's list.
To have 14 Brazilians on this list, we would have to advance to position 11.126 (almost double) and we would only have three names that coincide with the Clarivate list.
Naturally, the two lists point to researchers with different affiliations: of the 14 researchers in the Clarivate ranking, 9 are from the State of São Paulo; in the other list, only 2.
The truth is that almost everything changes.
OK, the methodologies are different, but if they want to measure the same thing, the least that can be said is that there is a lack of convergence (I dare not say consensus) on how science should be evaluated. It is suggested that the science of science is far from being exact, even though the indicators are used with a supposed accuracy and objectivity.
A colleague showed me another source that caught my attention, the website research.com. One of the rankings there is called Best Scientists in the World 2024 Ranking. The numbers presented are impressive. It is worth a visit, at least out of curiosity.
To be in first place in a global ranking with around 2 thousand researchers per area of knowledge[1], it is necessary to have a D-index that varies from 128 to 400 (the D-index is the H-index looked at within a disciplinary area; it is very close to the H-index depending on how the researcher publishes).
That is, at least 128 articles with 128 citations and at most 400 articles cited at least 400 times each.
The average number of publications by the top-ranked researchers in each of the 26 areas of knowledge varies from just over seven publications per year throughout their lives to 90 articles per year. The average is 30 and the median is 24 articles per year during each year of a researcher's “productive” life.
In this ranking, the average “productive life” of researchers considered “best scientists” is 47 years old and the median is 51 years old (with a minimum age of 29 and a maximum of 60 years old for the top finishers in each area).[2]
The range of numbers varies according to the area of knowledge. On average, a researcher, to be a “best scientist"according to the ranking, it would need to publish 24 articles per year every year for 47 years! The median, which is fairer than the average due to the range of numbers, is 21 articles per year, an average of 1,7 articles per month.
There are those who have published 90 articles per year during their 36-year career, something like a paper every four days. An impressive productivity.
Computing all areas of knowledge as a whole, of the thousand researchers best placed in the ranking, there are no Brazilians, only one Latin American (an Argentinean), 606 Americans and one hundred British, leaving very little to distribute among the rest of the world.
I have compiled and show some additional data from the 26 areas of knowledge in the Best Scientists ranking in Table 1.
Table 1 – Compilation of data from the “Best Scientists” ranking on the research.com platform
Some interesting facts can be extracted from Table 1.
- Of the 26 areas of knowledge, 12 have researchers from countries other than the United States and Canada, considering the top ten in the ranking.
- Australia and China are the most frequent intruders.
- Only 5 of the 26 areas of knowledge have female researchers among the top ten.
- Of the approximately 260 researchers in the top ten of the 26 areas[3], only 7 are women.
- The participation of Brazilian researchers (men and women) among the top 2 in each area represents more than 3% in seven areas.
- In four areas, Brazilian participation is very close to or above 6%.
- The participation of Brazilian female researchers is more expressive precisely in these four areas.
- Of the total number of Brazilians present in the lists of areas of knowledge, around 20% are women.
- The participation of Brazilians in the total number of ranked researchers in all areas is around 0,2%.
I have no doubt that the names that appear in the various rankings are of excellent scientists. It is unquestionable that they are very good, exceptional even. Perhaps one or two exceptions can be found in which the researcher, despite having extraordinary indicators, faces integrity problems. But these would indeed be exceptions, easily detectable.[4]
It may be that part of my interest in these rankings comes from my envy of not being on them and the consequent desire to know how the lists of the best, most cited, most influential researchers are formed.
Another part comes from the interest, as a researcher, in explaining evidence such as the incredible predominance of American and British researchers (70% of the best in the world are in just two countries!); the glaring low presence of women among the best; and the incredible record of publishing a paper every four days for 36 years, or even two articles a month, every year, for 47 years straight.
The methodologies vary, of course, but they all revolve around the conviction that the quality of research is measured by the number of publications and citations, since they occur on a neutral and unbiased plane.
PS: Curious as I am, I asked ChatGPT what the avatar of a best scientist based on the data reported here. The image that presented itself to me was this:
The content of this text does not necessarily reflect the official position of Unicamp..
[1] Some areas have just under 2 researchers listed, somewhere between 1.800 and 1.900. Here we consider, without losing out on the analysis and to make the work easier, that all of them have 2.
[2] These numbers were calculated by the author of this article based on the life expectancy of each person after the age of 25. In the absence of a specific age, the number of years since the doctorate was used. This is an approximate measurement and is not intended to be a reference.
[3] The number is approximate because some researchers appear in more than one area of knowledge.
[4] The Stanford/Elsevier rankings began excluding retractions from their lists this year.
