In recent years, China has become a world leader in a key measure of scientific impact: the number of academic papers produced by researchers there that are then widely cited by other scientists.
Now, two analyses identify one factor that might be helping boost these citations: An unusually high number is coming from scholars also based in China. One study reports that more than half of citations to the top 10% of China’s highly cited papers come from the same nation’s academics. The second finds a similar trend—and suggests China’s global research ranking is lower than it at first appears.
Citation analysts have long known scientists working in one country tend to frequently cite papers produced in the same nation. But the two recent analyses—which were not published in peer-reviewed journals—show China stands out when it comes to home preference.
One, released in August by Japan’s National Institute of Science and Technology Policy (NISTEP), mined the more than 1 billion citations recorded in Clarivate’s Web of Science database. Analysts identified the top 10% most highly cited papers by authors in 25 countries published in the years 2020–22. They then assigned citations of those papers to a country, based on the affiliations of the authors of the citing papers. (When the cited and citing paper had authors from multiple countries, they assigned fractional values.)
Overall, they found that 62% of citations to China’s top 10% of papers came from within the country. The United States had the second-highest rate of home bias at 24%. Other developed nations had same-country citations ranging from Italy’s 13% to Canada’s 6%.
There are several reasons behind China’s home bias in citations, analysts say. One is that researchers in China are producing “a growing body of high-quality work,” says Futao Huang, a higher education scholar at Hiroshima University. In addition, he says, many Chinese institutions have adopted a “strategic focus on publishing in high-impact journals,” which get greater attention from scientists. There has also been a “rapid growth of the Chinese researcher population” that is more aware of work being done across China, says Li Tang, a science policy specialist at Fudan University. She adds there is also a Chinese culture of “guanxi,” or mutual support. These factors “interact with each other and contribute to China’s high level of internal citations,” Tang says.
Shadier practices might also contribute. In a strategy known as “citation stacking,” for example, scientists cite work that may have little relevance to their paper in order to boost the citation counts of colleagues and institutions. Citation stacking authors expect colleagues to return the favor and to benefit from increased institutional prestige.
The NISTEP analysis, included in its annual report Japanese Science and Technology Indicators 2024, does not attempt to distinguish gratuitous from more legitimate citations. And it also finds that researchers based in the U.S. and Europe are increasingly citing papers produced in China. That suggests China is doing “highly impactful research,” says NISTEP bibliometric analyst Murakami Akiyoshi. But, “The high proportion of country self-citations in China is something to keep in mind when considering international comparisons and rankings,” Murakami says.
In the second analysis, Claudia Steinwender of the Ludwig Maximilian University of Munich and two colleagues used a new approach to quantify just how China’s home citation bias influences its global ranking. The researchers started by using Clarivate impact factors—which are based on how many times a journal is cited—to identify 461 journals that comprise the top 10% of academic publications in 20 broad scientific fields. They then searched issues of those journals published between 2000 and 2021, identifying more than 200 million pairs of cited-citing papers.
Papers produced in China received 57% of their citations from within China, the largest proportion among the countries studied, the researchers reported in a working paper published in May by the National Bureau of Economic Research. The U.S. had the second-highest rate of home citations, with 37%.
Those numbers weren’t surprising, Steinwender says, because “large countries will naturally have a large share of home citations because there are just many potentially citing researchers.”
The team—made up of three economists—noted that a home-country bias is also a feature of international trade: Countries preferentially consume goods produced close to home, with larger nations seeing a larger impact. Economists have developed analytical techniques to account for this size bias, and Steinwender and her colleagues adapted one in effort to understand how China’s size—as measured by total publications and total citations—was influencing its citation patterns. They found that China’s home bias was the largest among major countries, suggesting China’s home citations “are larger than what we would expect given its size,” Steinwender says. When the researchers corrected for that home bias, China dropped from second to fourth in a ranking of total citations received in the top journals from 2000 to 2021, behind the U.S., the United Kingdom, and Germany.
The work suggests “China’s apparent rise in citation rankings is overstated,” Steinwender and her colleagues write. It also suggests policymakers in nations competing with China could benefit from a more realistic assessment of its scientific prowess, they note. “Alleviating the [West’s] existential dread of losing a scientific showdown with China could … foster international collaboration,” they write.
Steinwender’s “debiasing” technique is just one of several approaches researchers are using to try to more accurately identify notable papers and compare the scientific impact of nations, says Caroline Wagner, a science policy scholar at Ohio State University. She notes that citation counts are further skewed by fraud, plagiarism, and low-quality open-access journals, and are “truly distorting the measures we have used for decades to assess [research] output and impact.” Such information is not just important for bragging rights, she notes. It can also affect career advancement, the ability to attract collaborators and students, and national funding priorities. Accurately evaluating citations, she says, “is one of the challenges in the field right now.”
In the meantime, papers by researchers in China continue to attract more citations. Last week, the Xinhua news agency reported that, over the past decade, those papers garnered 16.2 citations on average, topping the global average of 15.76, according to the Institute of Scientific and Technical Information of China.
