Correlation between International co-authorship rate and CPP in 5-year interval
Figures 2 and 3 show the 5-year ESI CPP trends as a function of 5-year international co-authorships rate trends for selected young and old universities. While old universities have higher CPP in general, there are strong correlation between international co-authorship rate trends and 5-year CPP trends. For example, the CPP increased 4.12 cites for every 10 % increase in international co-authorship rate for Massachusetts Institute of Technology (MIT, USA), 3.42 cites for University of Oxford (U Oxford, UK), and 3.01 cites for Stanford University (Stanford U, USA). Among young universities, for Nanyang Technological University (NTU, Singapore), it is 2.24 cites per 10 % Intl Collab increment, and that for Plymouth University (Plymouth U, UK) is 3.02 cites, and 0.73 cites for King Fahd University of Petroleum and Minerals (King Fahd U PM, Saudi Arabia).
Figure 4 shows the ΔCPP trends for publications with and without international co-authorships for (a) Caltech, Univ Tsukuba and Univ Melbourne, and (b) HKUST, NUS and NTU. It can be seen that for Caltech, Univ Melbourne and Univ Tsukuba, the CPP difference between their international collaborated publications and their publications without international co-authorship is approximately 4–5. This explains their performance in Figs. 2 and 3: with the increase of international co-authorship rate in their publications, the overall CPP of their papers has more weight from their international co-authored publications, and the overall CPP of their publications are increased. Yet, for HKUST, NUS and NTU, the CPP gaps between publications with and without international co-authorship are relatively small (around 0–1 citations per paper increment). This is because the fact that these institutions have attracted a lot of researchers with international background to work in these institutions. By internalizing the collaborating “external” authors, a special kind of international collaboration has been created that are not expressed in co-authorship, which makes the difference between their national research and international collaborated research relatively small.
Figure 5 shows the relative CPP increment over the last 5-year period for selected young and old institutions. It can be seen that young institutions has relatively higher relative CPP increment over the last 5-year period compared to that of old institutions.
Increment of field weighted citation impact (FWCI) of internationally co-authored papers over the FWCI of the involved institutions
Figure 6 shows (a) the increment of FWCI for internationally co-authored papers over the overall FWCI of the two collaborating institutions among the selected 8 old institutions and 8 young institutions, and (b) the FWCI increment for internationally co-authored papers over the overall FWCI of the two collaborating institutions among the selected “lower ranked” 10 old and 10 young Universities (those in the 200–250 rank universities in the 2014 Times Higher Education WUR).
For the 16 renowned young and old universities, 57 bilateral collaboration couples with 50 and more co-authored publications are identified, and the FWCI increment data for these collaboration couples are include in the plot. The original data for the plot are provided in Tables 1 and 2. Some specific pairs of universities in Tables 1 and 2 showing the largest/lowest impact increase are chosen and the collaboration types are analysed, as shown in Table 3. It can be seen that, international co-authorship benefits both the young and the old institution, with the old institution to old institution collaboration provides the highest FWCI increment, followed by the old institution to young institution collaboration. Young institutions profit from their international collaboration with renowned universities. This may also apply to the national collaboration with renowned local universities. As mentioned in Introduction, internationally collaborated papers will be more visible and more frequently cited in prestigious journals than papers without international collaborations, and so the collaboration with well-known national institutions may also be beneficial to young universities. Among the 57 bilateral collaborations, only 3 involved young institution to young institution collaboration, indicating that there are untapped potential for enhancement on bilateral collaboration among young institutions. From Fig. 6b, we can see that, compared to the renowned universities, those not well-known universities have less collaborations (with 50 and above collaborated publications) among them. There are only 15 old–old collaborations and 6 old–young collaboration found, and there is no collaboration among young to young universities, indicating that there is still large room for the young–young collaborations among the not-so-well-known institutions. It can also be seen from Table 3 that multinational collaboration is the dominant collaboration type for the selected institution pairs, and publications from multinational collaboration have higher citation impact than the publications by binational/bilateral collaborations.
Moed (2005b) has done similar pair-wise analysis of incremental impact increase in his chapter “Does scientific collaboration pay?”. He found that when scientifically advanced countries collaborate with one another, they profit in around 7 out of 10 cases from such bi-lateral collaboration, in the sense that both raise their citation impact compared to that of their ‘purely domestic’ papers. But when advanced countries contribute in bilateral international co-authorship to the development of scientifically less advanced countries—and thus to the advancement of science in the longer term than the perspective normally adopted in research evaluation—this activity tends to negatively affect their short-term citation impact, particularly when their role is secondary. As mentioned in Introduction, it would be very interesting if one could exam the “research guarantor” indicator on the international co-authorship of the young institutions. Yet, we will not address this in the present study.
Correlation between research expenditure in financial year 2013 and 5-Year CPP (2009–2013)
Figure 7 plots the CPP of selected young and old institutions versus the research expenditure in financial year 2013. It can be seen that old institutions has higher research expenditure in financial year 2013 as compared to young institutions.
Trends of Difference between percentage of international co-authored publications falling in global top 10 % highly cited publications and that for all publications (Δ%Top10%)
Figure 8 shows the difference between the percentages of international co-authored publications for an institution falling in the ESI global top 10 % highly cited publications and the percentage of all publications of the same institution falling in the ESI global to top10 % highly cited publications (Δ%Top10%). It can be seen that for all the selected young and old institutions, this difference is generally positive, means that internationally collaborated publications generally have a higher rate of high citation publications among all publications. Yet, this difference varies from one institution to another institution. For some renown world top universities like Caltech, Stanford University and University of Cambridge, although their overall CPP for their publications is already very high, the percentage of their internationally collaborated publications falling in the global top 10 % highly cited publications is still higher than the percentage of their overall publications falling in the global top 10 %. Further investigation is needed to have an adequate explanation for this phenomenon.
Table 4 provides the 5-year CPP trends as a function of MGCD. It can be seen that although the old universities has a higher CPP value in general, young institutions have relatively higher CPP increment over MGCD increment.