That China, one of the lowest income
countries in the world at the turn of the 21st century, became a
super-power in scientific knowledge in less than two decades is a
remarkable development in the history of science. The way China deploys
its newly developed scientific resources will drive the direction of
science and technology into the foreseeable future and the direction of
our increasingly knowledge-based economy.
From
2000 to 2016, China jumped from bit player to star performer in
physical science and engineering (S&E) research. As Xie, Zhang and
Lai (2014) document, China invested heavily in S&E in the 2000s,
becoming a world leader in bachelor’s and master’s degrees and a huge
producer of S&E PhDs and became the biggest source of international
students, who earn S&E PhDs in the US and other advanced countries.
It also increased its R&D and number of researchers hugely. The
country’s R&D spending exceeded EU spending and should surpass US
spending by 2020 at the latest.
The
investment in scientific resources paid off in a huge rise in China’s
share of scientific papers and citations in the Scopus database that
indexes global scientific publications. In 2000, Chinese addresses
accounted for 4% of papers and less than 2% of citations. China topped
the US in number of papers published in 2016, generating headlines
(Tolleson, 2018). Impressive as these statistics are, our research (Xie
and Freeman, 2018) shows that they massively understate China’s
contribution to global science in two ways.
First,
measures of scientific contribution by the address of researchers gives
China no credit for papers written by Chinese researchers with
non-Chinese addresses. It counts a paper with, say, five Chinese named
authors working in the US as a US paper just as it would a paper with
five authors having American names. The missing contribution is large,
as China’s diaspora research community is such that in 2016 17% of
non-China addressed articles had at least one Chinese named author.
To
take account of Chinese researchers working outside China, we modify
the standard address-based measure of contribution with an
address-and-names metric that gives ½ credit for China’s share of
addresses and ½ credit for Chinese share of names on a paper. We
distinguish persons from China by first names as well as surnames,
counting Xu Wang as from China but not David Wang. Since nearly all
names on China addressed papers are Chinese, while many non-Chinese
addresses have a Chinese named author, the adjustment increases China’s
share of papers. It raises China’s share in 2016 by nearly one third,
from 18.0% of papers in the weighted address measure to 23.3% of papers
in the address-and-names measure.
Second,
while Scopus includes some Chinese journals in its bibliometry, over
80% of its journals are in English, and it covers only 8% of the 4,216
science, engineering, and math journals that the China National
Knowledge Infrastructure (CNKI) reports as published in China. Scopus
presumably chose outstanding Chinese journals for inclusion, but the
journals excluded from its database almost certainly contain some useful
and interesting science. In any case, the magnitude of the missing
scientific papers is huge. As Figure 1 shows, CNKI journals published approximately the same number of
articles (1.6 million) in 2016 as Scopus – the results of a huge
increase in CNKI publications beginning in the 1980s.
Figure 1: Numbers of S&E Journal Articles in Scopus and in CNKI, 1980-2016.
If
the scientific content/impact of Chinese language papers was on a par
with that of English or other language papers in Scopus, the roughly
equal number of CNKI and Scopus articles would imply that China was
responsible for about 2/3rd’s of scientific work in 2016: ½ from CNKI
journals and ~ 1/3 of the ½ from Scopus.
But
CNKI articles do not have the same quality/impact as international
journal articles. Fewer scientists read Chinese than English. CNKI
papers are shorter and have fewer references than Scopus papers. China’s
requirement that PhD’s and master’s candidates publish thesis papers
for a degree leads to many publications with a narrow scope that would
elsewhere place them in university libraries. Indicative of the quality
difference, 44.6% of CNKI papers published in 2013 received no citations
in the succeeding three years compared to 29.0% of Scopus papers
published in 2013. Recognizing the higher impact/quality of English
language publications, Chinese universities offer sizable incentives for
publishing in English language journals, which induces researchers to
send their best work overseas.
To
take account of the missing Chinese scientific literature and obtain a
valid estimate of China’s contribution to science worldwide, we need an
“exchange rate” measure of comparability between publications in the two
databases. How valuable is a CNKI article relative to a Scopus article
in contributing to science?
We
use citations to answer this question. While imperfect, citations are
the most widely used and objective indicator of the quality/impact of an
article. We focus on papers published in 2013, which allows at least
three-year forward citations in our data. Both Scopus and the CNKI count
citations within their own database. A 2013 Scopus journal article
averaged 9.2 forward citations from other Scopus articles while a 2013
CNKI journal article averaged 2.3 forward citations from other CNKI
articles. This suggests a citation-based exchange rate of about 0.25 (=
2.3/9.2) for CNKI articles compared to Scopus articles.
But
this excludes citations across the databases, which neither database
counts. To estimate cross-database citations, we drew random samples of
2000 non-Chinese language Scopus papers and of 500 Chinese language
papers in CNKI from 2013 to 2017 and counted their references to 2013
publications. References are, by definition, backward citations from
later papers to earlier papers, and thus the forward citations of
earlier papers. CNKI papers are far more likely to cite Scopus articles
than the reverse. About half of journal references in CNKI articles to
2013 publications were to Scopus articles, while just 0.29% of journal
references in Scopus articles to 2013 publications were to CNKI Chinese
language papers. Extrapolating, we estimate that 2013 Scopus articles
received 3,276,350 citations from CNKI articles through 2017 whereas
2013 CNKI articles received l32,196 citations from non-Chinese language
Scopus articles. Adding these citations to the number of citations in
Scopus and CNKI reduces the exchange rate of a CNKI journal article from
0.25 to 0.20 of a Scopus paper. Valuing a CNKI publication at 1/5th of a
Scopus publication we estimated the total number of Scopus equivalent
papers in the two data sets and found that China contributed 36% of
these articles.
Rising quality of Chinese scientific research
We
explored further the quality of Chinese scientific articles in the
Scopus database by analyzing the citations those papers received from
other Scopus papers. In 2000, papers with all-Chinese addresses
received just 29% of the world average of citations while international
collaborations and papers with Chinese names working at non-Chinese
addresses received more citations than the world average. The best
research by Chinese scientists was being conducted outside of China. By
2013, citations to papers with all-China addresses increased to 70% of
the global average while collaborative work and work done outside China
converged toward the average. China’s share of global citations rose
from 7.4% in 2000 to 19.5% in 2013, due primarily to the increased share
of citations to all-China addressed papers.
As
a final look at the quality of China’s contribution to science, we
examined the percentage of Chinese names and Chinese addresses in papers
published in Nature and Science. In 2016, about 20% of names on papers
in these journals were Chinese while 8% to 9% of addresses were Chinese
– far above 7-8% of names and 0.5% of addresses in 2000.
In
total, we estimate that China obtained 37% of Scopus equivalent
citations. With 18% of the world’s population and world GDP, China’s 36%
of 2016 papers and 37% of 2013 citations show that it is essentially
contributing twice its weight to the advance of science. While our
calculations ignore scientific articles outside Scopus in languages
other than Chinese, we estimate that taking account of these would lower
our estimated China contribution by less than 3 to 4 percentage
points.
Conclusion
That
China, one of the lowest income countries in the world at the turn of
the 21st century, became a super-power in scientific knowledge in less
than two decades is a remarkable development in the history of science.
The way China deploys its newly developed scientific resources will
drive the direction of science and technology into the foreseeable
future and the direction of our increasingly knowledge-based economy. In
the 19th century, Horace Greeley famously advised Americans to “Go
West, young man, and grow up with the country.” In the 21st century,
science is going East and will grow up with China.
(Qingnan
Xie, Nanjing University of Science &Technology & Labor and
Worklife Program, Harvard Law School; Richard B. Freeman, Harvard &
the NBER.)
References
Tollefson, Jeff (2018). “China Declared World’s Largest Producer of Scientific Articles,” Nature, News, 553 (25 January): 390. doi.org/10.1038/d41586-018-00927-4
Xie,
Qingnan, and Richard B. Freeman (2018). “Bigger than You Thought:
China’s Contribution to Scientific Publications,” NBER Working Paper
24829 (July).
Xie, Yu, Chunni Zhang, and Qing Lai (2014). “China’s Rise as a Major Contributor to Science and Technology,” PNAS 111(26) (July): 9437-9442. doi.org/10.1073/pnas.1407709111.