Do countries with lower self-citation rates produce higher impact papers? or, does humility pay?/?Paises con menores tasas de autocitacion producen publicaciones de mayor impacto? o ?Paga ser humilde?/Paises com menores taxas de autocitacao produzem publicacoes de maior impacto? ou, vale a pena ser humilde?
Studying the 62 countries producing most papers reported in the SCImago data base in the period 1996-2008, it was found that countries with low per capita publication numbers show variable rates of self-citations and produce publications with lower citation impact. In contrast, countries with larger numbers of citations per paper have also high per capita publication numbers and their researchers appear to be humbler, showing lower rates of country and author self-citations. Notable exceptions are China, USA and Iran, which show abnormally high country self-citation rates, partially explained respectively by large populations, large total number of publications and language barriers. An increase of self-citation rates in almost all countries during the last decade, calls for exploring science policies that increase international scientific impact, such as more international cooperation, and science education with broader outlooks.
El estudio de los 62 paises de mayor produccion cientifica del mundo reportados en la base de datos de SCImago para el periodo 1996-2008 revela que los paises con un bajo numero de publicaciones per capita muestran tasas variables de autocitas de otras publicaciones de sus paises y producen publicaciones que reciben un bajo numero de citas. En contraste, los paises con mayor numero de citas por articulo, tambien muestran un elevado numero de publicacion per capita y sus investigadores parecen ser mas humildes, mostrando una menor tasa de autoci tas de autor y de pais. Excepciones notables son China, EE. UU. e Iran, que muestran tasas muy altas de auto-citacion del pais, lo que se explica en parte por su gran poblacion, su gran numero total de publicaciones y barreras del idioma, respectivamente. Un aumento importante de la auto-citacion en la ultima decada en casi todos los paises, llama a explorar politicas cientificas que busquen aumentar el impacto cientifico internacional, tales como mayor cooperacion internacional y una educacion de la ciencia con perspectivas mas amplias.
O estudo dos 62 paises de maior producao cientifica do mundo relatados na base de dados de SCImago para o periodo 1996-2008 revela que os paises com um baixo numero de publicacOes per capita mostram taxas variaveis de autocitas de outras publicacOes de seus paises e produzem publicacOes que recebem um baixo numero de citacOes. Em contraste, os paises com maior numero de citacOes por artigo, tambem mostram um elevado numero de publicacOes per capita e seus investigadores parecem ser mais humildes, mostrando uma menor taxa de au tocitacOes de autor e de pais. ExcecOes notaveis sao a China, EE. UU. e o Ira, que mostram taxas muito altas de autocitacOes do pais, o que se explica em parte por sua grande populacao, seu grande numero total de publicacOes e barreiras do idioma, respectivamente. Um aumento importante da autocitacao na ultima decada em quase todos os paises, e um convite a explorar politicas cientificas que busquem aumentar o impacto cientifico internacional, tais como maior cooperacao internacional e uma educacao da ciencia com perspectivas mais amplas.
KEYWORDS / Country Citation / Impact / Productivity / Scientific Publications / Self-Citation /
"The principle of science, the definition, almost, is the following: The test of all knowledge is experiment. Experiment is the sole judge of scientific 'truth'. But what is the source of knowledge? Where do the laws that are to be tested come from? Experiment, itself, helps to produce these laws, in the sense that it gives us hints. But imagination is also needed to create from these hints the great generalizations -to guess at the wonderful, simple, but very strange patterns beneath them all, and then to experiment to check again whether we have made the right guess" (Feynman, 1964). These are tine words, but often, the amazing intellectual creation of humans: Science, is handicapped by this very same imagination. Many scientists believe so strongly in the dictates of their own mind that they shun reality (Jaffe, 2010). This is especially evident when comparing soft with hard sciences regarding falsifiability (Fanelli, 2010) or skepticism (Jaffe et al., 2010); where in the softer sciences, subjective imagination is more frequently in better regard than experiment.
The balance between objective experiment and subjective imagination can vary enormously, inviting the question of whether an optimal balance for scientific creativity between these two elements exists. Attitudes favoring general creativity are strongly correlated with economic development, and include tolerance and openness to other ideas (Florida, 2005). Comparing specific attitudes in different countries showed that scientific and economic development correlated with attitudes favoring skepticism, tolerante and openness (Jaffe, 2005). Thus science seems to be favored when subjective imagination is kept in check.
Self-citation is a necessary tool in normal scientific publishing. Yet the degree to which authors cite their own work (author self-citation) or cite works performed by researchers in their own country (country self-citation) varies widely. Self-citations have various functions and what scientometrics can extract from statistics tracking self citations is complex and variable (Aksnes, 2003). Part of this variation might be related to attitudes of scientists concerning openness to the ideas of other scientists, self-valuation and tolerance, i.e humility. Here, this possible relationship is explored in some detail by comparing self-citation rates in different countries.
One dimension of the balance between the subjective and the objective is the openness towards worldviews regarding the balance between world-wide interests and personal, local or national interests. Here it is assumed that this openness is at least partially reflected in a greater citation rate of scientific research performed by others, regardless of the country of origin. This openness in citations is by definition negatively correlated with country and author self-citation rates (the ratio between self-citations to total citations in a document). Data for self-citation (Table I) was calculated from over 19.5x[10.sup.6] documents indexed by SCImago (2007) of the Universidad de Granada, Spain, based on academic publications from nearly 18,000 titles compiled by Scopus (2010). The rate of country self-citations was calculated by dividing the total number of country self-citations, according to the country of residence of the corresponding author given by SCImago, by the total number of citations for each country. This self-citation rate was compared with other indices such as number of publications per capita and average citation rates of documents for each country. Only data for the 62 countries with more than 10000 publications, as recorded by Scopus between 1996 and 2008 are presented. Data for gross domestic product (GDP) and population size for each country are from the World Bank (2009). Other data are from references as cited in the text. All data can be accessed freely at the websites of Scopus and the World Bank. Statistical analysis was performed using the commercial software Statistica 8 (StatSoft, 2007).
Data from Scopus was checked for their robustness by comparing the statistical correlation between GDP and number of publications with those calculated from reports by the Science Citation Index and by Google Scholar. No statistically significant differences between these correlations could be found. Part of these comparisons has been published elsewhere (Jaffe, 2005).
Results and Discussion
Figure 1 shows that low rates of country self-citation correlated with high per capita publication numbers and high citation impact (citations per document) of the publications. This trend was statistically highly significant (Spearman correlation coefficient= -0.322, and probability of rejecting the null hypothesis p<0.01) when comparing rates of self-citations with the number of publications per inhabitants, a still larger correlation index of -0.438 (p<0.0003) was found for country selfcitations and number of total citations received by the country. It was found that countries with low numbers of scientific publications per capita show higher rates of self-citations and produce publications with lower citation impact. At the same time, countries with widespread scientific activity, indicated by large numbers of publications per capita, seem to be humbler and tend to show lower rates of self-citations. Although countries with low numbers of scientific publications per capita show in average higher rates of self-citations, many exceptions exist. For example, Latin American countries (bold names in Figure 1) showed large variations in country self citation rates, with Brazil and Argentina using much higher self citation rates than expected from the regression, whereas Colombia and Venezuela showed much lower rates.
The exceptions to this rule were the very high self-citation rates in China, USA and Iran. These oddities are not due to statistical fluctuations, as self-citation rates were calculated based on over 1.2 and 4.3x[10.sup.6] documents for China and the USA re spectively. These results can be understood if we take into account the total number of publications per country and assume that countries with larger absolute academic productivity will have larger country self-citation rates as ir will be more likely by pure chance that cited documents are from the same country. The data show a positive correlation between the total number of country self-citations and total number of citable documents (correlation coefficient= 0.58, p<0.0001). Other researchers reported oriented citation bias for the USA, partially explained by the large cumulative citation number for papers originating from this country (Pasterkamp et al., 2007). A network analysis of co-authorship (Royal Society, 2011) using the documents compiled by Scopus, revealed a similar special status for the USA. Most countries cooperate with researchers in the USA, but researchers in the USA have a low cooperation rate compared with those from other countries.
The result for China can be explained with a similar correlation between self-citations and population size (correlation coefficient= 0.65, p<0.0001). A similar conclusion for China, using a different experimental approach was obtained by Minasny et al. (2010). The result for Iran has no such explanations, but could be due to language (Moed, 2005), which limits Iranian researchers to publish and cite in local journals (Biglu, 2007).
A multiple regression study with country selfcitation rates as the dependent variable is presented in Table II. It confirms that self-citation rates are explained by several factors, of which at least three can be identified here. The total number of documents produced in a country is a strong predictor for country selfcitations, followed by population size of the country. Yet the relationship between self-citation rates and the number of citations per document published is also a strong factor identified by these statistics.
Self-citation rates increase over time. Comparing the average selfcitation rates in the 62 countries in 1996 to those in 2009 showed that the mean self-citation rate in 2009 was 28.9% higher than in 1996. This difference was statistically highly significant (t-test for dependent samples: t= 9.8, p>>0.0001), and suggests that newer publications everywhere are decreasing their international citation rates. Only countries with a relatively small scientific output, i.e. Cuba, Argentina, Latvia, Venezuela, Jordan and Georgia, decreased their country self-citation rates in that period.
Does country self-citation differ from author self-citations? Author self-citations, "those where authors cite their own works--account for a significant portion of all citations. These self-references may result from the cumulative nature of individual research, the need for personal gratification, or the value of self-citation as a rhetorical and tactical tool in the struggle for visibility and scientific authority" (Fowler and Aksnes, 2007). These authors found among Norwegian scientists that the more one cites oneself the more one is cited by other scholars; yet Aksnes (2003) also reported for this sample that the highest share of selfcitations was found among the least cited papers. That is, author self-citation averages for countries show the same negative correlation with average citations per documents as shown here (Schubert et al., 2006); although they did not analyze their data that way, when joining data from these authors with the ones presented here we get the relationship shown in Figure 2. Clearly, author self-citations follow the same trend regarding citation impact as country selfcitation. A similar correlation was found by Glanzel et al. (2004) who found a negative correlation in 50 countries between the share of author self-citations and an index of citation impact, the mean expected citation rate. This trend varies between disciplines (Snyder and Bonzi, 1998; Glanzel and Thijs, 2004), but always a low author selfcitations correlates with higher impact factors. This correlation (Figure 2) is highly significant as indicated by a Spearman correlation coeffi cient (-0.89, p<0.0001) between the average author self-citation rate for each country and average citations per document of the 40 countries selected by Schubert et al. (2006).
[FIGURE 1 OMITTED]
[FIGURE 2 OMITTED]
There is no reason for condemning self-citations in general (Glanzel et al., 2006). Self-citations are an integral part of the way we advance in science and a moderate level of self-citations is indicative of consolidated scientific activity in the group and country of the authors. There might be different motivations for author and country self-citations. In addition, the reasons for each might be manifold. High self-citation rates might be explained by relative isolation in research. This fact might explain higher self-citation rates in countries with low density of scientists and or low publication numbers per capita, but not the trends found for country self-citations. Globalization has made research more of an international enterprise (Royal Society, 2011), and citations normally cover work produced in many different countries. Thus other explanations for this trend can not be dismissed. It can be suggested that high rates of self-citation produced by low numbers of non-self-citations might be expected from scientists with a relative lack of interest in the scientific activity of others. This last suggestion is supported by the fact that both, author self-citation and country self-citation correlate negatively with the scientific impact (citation rates) of the paper. Citation rates are modulated by a variety of factors (Bornmann et al., 2008) but somehow reflect levels of visibility among the scientific community, although not necessarily the quality (Arnold and Fowler, 2011), which in turn will affect the influence the work might have on future research.
Statistical analysis has shown clearly that large numbers of country and author self-citation rates are negatively correlated with the average citation impact of the scientific publications produced in a country. This result complements the study by The Royal Society (Royal Society, 2011) that showed that scientific success is correlated with international cooperation. That is, less self-citation rates and more international cooperation produce better science. Correlation is no proof of causation, but everyday experience in science supports a common trend between international cooperation, empathy and citation impact. Country self-citations are increasing nowadays, despite a centrifugal dispersion of scientific activity from the USA and Europe to other countries as reported by Royal Society (2011) and Schubert and Glanzel (2006) among others. These facts are relevant to science policy and science education. If more cooperation and more out-looking attitudes favor higher impact science, then the trend towards increased country selfcitations detected here does not seem encouraging. This fact calls for science policies that specifically address this shortcoming. For example, more support for international cooperation might improve country self-citation rates, cooperation statistics, innovation and, eventually, better science.
If self-citation rates are ar least partially related to the balance of openness vs selfishness; broad world views vs local views; humility vs arrogance, then the results presented here are consistent with the view that more openness, broader outlooks, and larger doses of humility correlate with higher impact scientific productivity. Folk wisdom would have summarized the relationship reported here as 'arrogance increases ignorance'. Further research may throw more light into these relationships. Further work might clarify these relationships in the future.
The author thanks Wolfgang Glanzel and Rodolfo Jaffe for helpful comments on earlier versions of the manuscript.
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Klaus Jaffe. Chemist, Universidad Simon Bolivar (USB), Venezuela. Ph.D. in Biology, University of Southhampton, UK. Professor, USB, Venezuela. Address: Departamento de Biologia de Organismos, USB. Apdo. 89000, Caracas 1080, Venezuela. email: email@example.com
Received: 05/20/2011. Modified:08/22/2011. Accepted: 08/24/2011.
TABLE I DATA USED IN THE PRESENT ANALYSIS ORDERED BY COUNTIES FROM EUROPE, ASIA, AMERICA AND AFRICA * Country Population Nr. Of Document in millions documents per 1000 (2009) in Scopus inhabitants Norway 4.8 94,617 20 Poland 38.2 209,744 5 Portugal 10.6 72,826 7 Romania 21.5 42,320 2 Russia 141.8 405,499 3 Slovakia 5.4 35,274 7 Slovenia 2 29,493 15 Spain 46 449,406 10 Sweden 9.3 250,129 27 Switzerland 7.7 247,655 32 Turkey 74.8 171,048 2 Ukraine 46 74,325 2 United Kingdom 61.8 1,244,316 20 Australia 21.4 401,930 19 China 1317 1,223,278 1 Hong Kong 7 103,462 15 India 1140 393,536 0 Iran 72 68,401 1 Israel 7.3 154,402 21 Japan 127.7 1,224,465 10 Jordan 5.8 10,751 2 Malaysia 27.5 29,166 1 New Zealand 4.3 80,299 19 Pakistan 169.7 24,564 0 Saudi Arabia 25.4 26,763 1 Singapore 5 82,159 16 South Korea 48.8 319,976 7 Taiwan 23 233,763 10 Thailand 67.8 41,892 1 Argentina 39.9 73,705 2 Brazil 190 236,703 1 Canada 33 630,525 19 Chile 16.6 37,347 2 Colombia 44.4 14,754 0 Cuba 11.2 15,277 1 Mexico 107.4 96,625 1 United States 307 4,318,928 14 Venezuela 28.4 17,580 1 Algeria 34.4 11,664 0 Egypt 81.5 47,420 1 Kenya 38.7 10,026 0 Morocco 32 15,952 0 Nigeria 154.7 20,341 0 South Africa 49.3 71,731 1 Tunisia 10.4 17,785 2 Country Nr. Of Citations Rate of selfcitations per 1000 self inhabitants citation Norway 215,909 14.55 0.1745 Poland 373,845 6.91 0.2838 Portugal 137,362 10.49 0.2177 Romania 45,957 5.24 0.2470 Russia 577,757 4.61 0.3112 Slovakia 49,365 6.39 0.2331 Slovenia 44,163 7.37 0.2297 Spain 1,225,409 11.59 0.2650 Sweden 708,092 16.95 0.1766 Switzerland 643,764 19.44 0.1466 Turkey 259,644 6.37 0.2929 Ukraine 75,267 3.46 0.2969 United Kingdom 4,476,611 15.48 0.2482 Australia 1,101,340 14.05 0.2208 China 2,240,814 4.83 0.5176 Hong Kong 180,238 10.88 0.1815 India 729,613 6.09 0.3462 Iran 109,888 6.57 0.4194 Israel 340,029 14.75 0.1586 Japan 3,920,215 10.53 0.3139 Jordan 8,143 5.20 0.1751 Malaysia 23,912 6.20 0.1944 New Zealand 160,983 12.91 0.1738 Pakistan 26,902 4.53 0.3002 Saudi Arabia 19,320 5.35 0.1433 Singapore 109,807 9.91 0.1563 South Korea 530,243 8.53 0.2391 Taiwan 416,490 8.27 0.2582 Thailand 51,460 8.70 0.1851 Argentina 144,908 9.12 0.2328 Brazil 517,211 8.35 0.3202 Canada 1,803,543 15.54 0.2043 Chile 69,866 11.26 0.1982 Colombia 15,017 8.79 0.1530 Cuba 17,155 4.68 0.2601 Mexico 160,114 8.30 0.2287 United States 35,474,244 18.08 0.4684 Venezuela 19,204 7.14 0.1657 Algeria 8,760 5.12 0.2052 Egypt 55,012 5.62 0.2295 Kenya 19,244 11.80 0.1821 Morocco 16,051 5.48 0.1992 Nigeria 17,874 4.36 0.2538 South Africa 133,165 8.97 0.2285 Tunisia 16,222 5.15 0.2397 * Data extracted from documents compiled by Scopus from 1996 to 2008 as reported in SCI-7 mago website. TABLE II RESULTS FROM A MULTIPLE REGRESSION WITH COUNTRY SELF-CITATION RATES AS DEPENDENT VARIABLE, AS PRODUCED BY STATISTICA 8 Partial correlations Beta in Partial Semipart Tolerance Population 0.365 0.528 0.322 0.781 Total Documents 0.630 0.706 0.517 0.672 Documents / Population 0.071 0.066 0.034 0.237 Citations / Documents -0.527 -0.422 -0.241 0.209 Partial correlations R-square t(57) p-level Population 0.219 4.697 0.000017 Total Documents 0.328 7.533 0.000000 Documents / Population 0.763 0.503 0.617799 Citations / Documents 0.791 -3.513 0.000874
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