Cameroon publications in the Science Citation Index Expanded: Bibliometric analysis

Cameroon is one of the six countries of Central Africa with more than 20 000 000 residents. To characterize the Cameroon research performance, Cameroonians publications in the Science Citation Index Expanded during the period of 1936-2015, indexed in the Thomson Reuters SCI-EXPANDED database, were studied in this work. All documents of that period with Cameroon in the address field were included in the study. The document type, language, trend and collaborations were analyzed, as well as the output of different subject categories. Performances of countries, institutions and authors, including total, single, collaborative, first author, and corresponding author publications were also analyzed. Articles were analyzed by the scientific output and research performances of individuals, institutions and collaborative countries with Cameroon. Analyses included 8 457 articles (85 % of 10 591 Cameroonian publications). These bibliometric analyses of Cameroonian publications provided interesting insights concerning authors, institutions and collaboration patterns. Results showed that research in Cameroon was highly dependent on foreign collaborations, and the international collaboration was responsible for the increasing number of publications over the years. It was found that the articles with either first authors or corresponding authors from outside Cameroon got more citations than the others, and that the articles without any international collaboration had lower citations. The number of articles indexed by SCIEXPANDED has seen an increase in terms of Cameroonian articles that is considerably greater that the increase in number of all articles in SCI-EXPANDED. Articles were more frequent than other types of publication and they were mostly in English. The University of Yaoundé I ranked top one in inter-institutionally collaborative articles, the rank of the total inter-institutionally collaborative articles, and the rank of first author articles and corresponding author articles. The University of Yaoundé I also was in an absolute leading position from 1970s to 2015, followed far away by the other institutions. The categories of tropical medicine, plant sciences, environmental and occupational public health, and infectious diseases, represented the largest number of published articles. Even though physics and chemistry dominated the ranking of the top 20 best Cameroonian authors, an independent mathematics article was the most cited, with 60 citations in 2015 to a Cameroonian author. The top three productive researchers were T. C. Kofane, B. T. Ngadjui, P. Woafo, all from University of Yaoundé I. France and the USA dominated the ranking of countries with strong scientific collaboration with Cameroon. Rev. Biol. Trop. 65 (4): 1582-1591. Epub 2017 December 01.

enrolled.The need for decentralization of the university system in 1978 led to the opening of the first two academic centers, Douala and Dschang.Two other centers were added later: Ngaoundéré in 1982, and Buea in 1985 (Ndjodo & Onana, 2012).In 1992, on the eve of the university reform, the university system hosted more than 37 000 students.Despite the existence of provincial centers, the centralizing character around the University of Yaoundé, however, remained very strong, since the other four centers remained under-equipped.
In January 1993, a thorough reform of Higher Education took place and decree n° 92/74 of 13 April 1992 transformed the university centers into state fall Universities (Biya, 1992;1993).At the same time, a second university called Yaoundé II, Soa was created in the outskirts of Yaoundé.According to its legal and economic vocation, it hosted about 10 000 students in 1993 (Biya, 1993).The former lone university then became University of Yaoundé I, and hosted more than 25 000 students.Thus Cameroon became a state with six state universities instead of one.The balancing of these universities to provincial universities followed in subsequent years, and the capital did not welcome more students than it did in 1992.These six institutions operated the university system from 1993.Very recently, two other universities were created in the country, namely, the University Maroua (decree n° 2008/280 of 09 August 2008) and the University of Bamenda (decree n° 2010/371 of 14 December 2010).During that time, many independent research and national institutes were created.
The aim of this work was to analyze journal publications contributed by Camerounian researchers in the Science Citation Index Expanded (SCI-EXPANDED) of database from 1936 to 2015.This study was divided into three parts: first, we conducted the overall scientific performance of Cameroon in SCI-EXPAND-ED.The second section dealt with publication activities, with major focus on favored journals and subject categories, in which Cameroonian major international collaborating partners and national inter-institutional collaborating players were identified.Finally, the most cited papers were examined as statements of discipline emphases and impact.

DATA SOURCES AND METHODS
Science Citation Index Expanded (SCI-EXPANDED) of Thomson Reuters Web of Science Core Collection was used to collect the bibliographic data.An advanced research was conducted for documents with the phrase "Cameroon" in the country field.Initially, 10 591 publications were identified and these documents were published between 1936 and 2015 (Data last updated: July 15 th , 2016).
Document information including names of authors, title, and year of publication, source journals publishing the articles, contact address, and each year's citation time for every publication were downloaded into Microsoft Excel 2013 software and additional coding was manually performed for origin country, institutions of the collaborators and impact factors of the publishing journals (Li & Ho, 2008).The reported impact factor (IF 2015 ) of each journal was obtained from the 2015 JCR.The total number of times a document was cited from the Web of Science Core Collection since its publication to the end of 2015 was recorded as TC 2015 (Wang, Fu, & Ho, 2011).Likewise, C 2015 , the total number of citations of a paper in 2015 only (Ho, 2012) was employed to characterize Cameroon publications.In addition, the citations per total publications since publication (CPP = TC 2015 /TP), was also used (Chuang & Ho, 2015).
Articles originating from England, Scotland, Northern Ireland, and Wales were reclassified as originating from the United Kingdom (UK).
Affiliations in Yugoslavia were checked to be in Slovenia.
Affiliations in UKSSR were checked to be in Ukraine.
Affiliations in Greenland were checked to be in Denmark.
Affiliations in Reunion were checked to be in France.
Affiliations in Czechoslovakia were checked to be in Czech Republic (Czech Republic).
Affiliations in Zaire were checked to be in Democratic Republic of the Congo (Dem.Rep. Congo).
Affiliations in People's Republic of the Congo (Congo Peopl Rep) and Republic of the Congo (Rep Congo) were checked to be in Republic of the Congo (Congo).
Affiliations in USSR were checked to be in Armenia or Russia.
Affiliations in Federal Republic of Germany (Fed Rep Ger) were checked to be in Germany.

Document type and language of publication:
A total of 10 591 Cameroon publications with 12 documents types in the Science Citation Index Expanded from 1936 to 2015 were found.The majority of publications from Cameroon were formal articles: 8 958 (85 % of 10 591 publications), followed by meeting abstracts 842 (8.0 %), reviews 253 (2.4 %) and letters 232 (2.2 %) in the fourth position (Digital Appendix 1).Reviews had the highest citations per publication (CPP) with 17, followed by proceedings papers with 16, and 11 for each of articles and notes respectively.
Altogether 8 958 articles were extracted from the 10 591 documents for further analyses.Ninety-one percent of all these journal articles were published in English (8 141 articles), followed by French (804; 9.0 %), German (8 articles), Russian (2 articles), one in Italian and one in Chinese.One article was published in Soil & Tillage Research which was a bilingual (Afrikaans and English) journal.Cameroon is a bilingual country and the French-speaking area represents almost 80 % or eight regions against two English-speaking regions.
In Cameroon, there are eight universities with two in the Anglophone area: the University of Buea created in 1993 and the Bamenda created in 2010.Even though it is different for most Cameroonians to speak the English language at first, the study of English language only begins in secondary school in the Francophone regions.The fact that some journals agree to publish in French is therefore an advantage for them to avoid the English language.Another explanation is that Cameroon is the member of Francophonie, which involves countries whose official language is French and because of this, most documents are published in French.Today, 785 publications are made per year, up from 117 in 1993, showing a great improvement in Cameroon research.Analysis also showed that these articles have 54 566 authors, indicating an average of 6.1 authors per publication, proving collaborative rather than independent research in Cameroon.A probable reason is that, in Cameroon, institutions do not offer financial incentives for the publication of smaller works such as meeting abstracts and reviews, so authors concentrate their efforts in the publication of articles which are used in the upgrading of researchers.These results obtained indicate that Cameroonian researchers actively take part in conferences, and the number of reviews gives an idea of their performance.1 have a total of 5 285 (58.2 %) articles.These results showed that Cameroon is strongly dependent in terms of research.This high collaborative publication with France may be due to the fact that a number of lecturers in Cameroon studied in France, or had French fellowships, and they still maintain the relationship.Thus, due to the acute lack of equipment in Cameroonian universities, researchers are forced to seek foreign aid for their analyses.If Cameroon was independent in its research plan, and had adequate equipment, the research performance of Cameroon would have been better in the last 79 years.

Institutional comparisons:
For institutional studies the universities in Cameroon were grouped, for example, Univ.Yaoundé 1, Univ.Yaoundé I, Univ.Yaoundé were grouped  2. A ratio of institutional independent (single institution) articles: internationally collaborative articles: national collaborative articles (S:I:N) might be used to describe institutions or authors' publication characteristics (Fu, Long, & Ho, 2014).The S:I:N ratio of the University of Yaoundé I is 16:71:13, and it is different from that the University of Dschang which is 9.5:70:20, while that of the University of Douala is 3.4:78:18.Of all the top 12 institutions of Cameroon articles in the Science Index Expanded (Table 2) show that more than 60 % of the articles were international collaborative articles.The University of Maroua with S:I:N = 3.2:65:32 was less inclined to conduct institute and institutional independent research.This university also presented the smallest international collaboration.This is due to the fact the University of Maroua was just recently created in 2008 and most of its lecturers were already affiliated to those universities which existed since 1993.Table 2 demonstrates that the University of Maroua showed the highest national collaboration of 35 %.The University of Douala also presented poor institutional independent articles of 3.4 %.This ratio could show three important rates related to with college collaboration, which was more comprehensive and visual than just one traditional collaboration rate at a time for measurement and comparison (Fu et al., 2014)  under the name of teacher-researchers.In addition to the overall productivity of institutions, it is interesting to identify their independent paper (IC), collaborative papers (CI), first author paper (FP), corresponding author papers (RP) and institutional independent articles (II).
The absolute numbers along with the corresponding total productivity of each institution can be seen in Table 2. Fig. 2 shows the institutional yearly productivity for the five Cameroonian universities.From the results obtained, it is clear that the first publications of the University of Yaoundé I date back to 1973, followed by the University of Ngaoundéré before the growth observed from 2005.In addition, the University of Douala observed an increase in the number of publications from late 2014 to early 2015, while the other universities observed a decrease.The figure also shows that the universities of Douala, Ngaoundéré, and Dschang had publications before their creation in 1993.This is so because the sites where the universities are located had schools or training centers which were later transformed to universities.

Web of Science categories and journals:
Based on the classification of subject categories, the article output data was distributed into 169 SCI-EXPANDED subject categories.The top fourteen productive subject categories and the number of the journals of each category are shown in Fig. 3. (Note: Fig. 3 and Fig. 4 are in Digital Appendix 2) Tropical medicine (8.5 %) is at the top of Cameroonian publications, closely followed by plant sciences (8.4 %), then environmental and occupational public health (7.5 %), and infectious diseases (7.4 %).This ranking is dominated by activities related to research on medicinal plants.
Concerning the most cited 20 Cameroonian authors (Table 3, note: Table 3 and table 4 are in DIGITAL APPENDIX 3), authors from the field of physics occupied the first and third positions, while authors from biochemistry occupied the fourth position.The second, fifth, sixth, seventh and eight positions are occupied by chemistry authors, specifically authors in the domain of natural substances (plants) in organic chemistry.It was also noted that most of this plant extracts were analyzed for their pharmacological properties.(2004).
A strong conclusion can be drawn from Figure 4 that, neither the first author nor the corresponding author of the most cited article are Cameroonian.This is either due to the fact that the articles were published in research groups in which Cameroonians are members or they are articles arising from doctoral and postdoctoral fellowship programs.The Figure 4 demonstrates a good representation of independent articles of 6 %, 7 % of those whose first authors are Cameroonian, 6.9 % of those having Cameroonian corresponding authors and 6.9 % of those with Cameroonian being first and corresponding authors.Nevertheless, it can be concluded that Cameroonian researchers are mostly integrated into research groups abroad.The top institutional rankings are dominated by state institutions.This indicates that although there is no adequate research equipment, universities are the best research centers in the country.
This work presents a bibliometric analysis of articles published by at least one author from Cameroon during the period 1936-2015 and indexed in the Thomson Reuters SCI-EXPANDED database based on the production and citations, overall performance, subject categories, international and inter-institutional collaboration, and most cited paper.Cameroon has developed in scientific performance in 14 fields.Biochemistry and molecular biology and Pharmacology and Pharmacy were the two most productive fields to SCI papers.In terms of international collaboration, more than 90 % of all articles by Cameroonians papers were by international collaborations.Moreover, France and USA dominated the ranking of the more collaborative countries with Cameroon.For national/ inter-institutional collaboration, the University of Yaoundé 1 was the most productive institution and the other most productive universities were the University of Dschang and University of Douala.Furthermore, international collaboration enhanced the most citation-rate of papers in most fields.
Fig. 1.Trend of the number of publications referring to Cameroon in the Science Citation Index Expanded, citation versions articles.

Fig. 2 .
Fig. 2. The top five most productive institutions in Cameroon with more than 500 publications in the Science Citation Index Expanded.
Table 1 lists the first top 10 countries having high collaboration with Cameroon in terms of research.The number of internationally collaborative articles, the rank of the total internationally collaborative articles together with the percentage of total Cameroonians articles and rank of first author articles and corresponding author articles are also presented in Table 1.This collaboration is dominated by France, ranked first in collaborative publications with 2 549 (28 %) articles, and second in both first author and ranking of corresponding authors.USA follows far behind France with 1 130 (13 %) articles, with a third position occupied by United Kingdom in both first authors and ranking of corresponding authors.The top four countries in this Table

TABLE 1
The top 10 most frequently collaborative countries with Cameroon in the Science Citation Index Expanded CP: internationally collaborative articles with Cameroon; CPR (%): rank of internationally collaborative articles and percentage; FPR (%): rank of article with first author and percentage; RPR (%): rank of article with corresponding author and percentage.

TABLE 2
Top 12 institutions for Cameroon articles in the Science Citation Index Expanded (TP ≥ 100) TP: total number of articles; TPR (%): rank of total number of articles and percentage; % SI (SI): percentage in TP in an institute and institutional independent articles; % IC (IC): percentage in TP in an institute and number of internationally collaborative articles; % NC (NC): percentage in TP in an institute and nationally collaborative articles; % FP (FP): percentage in TP in an institute and first author articles; % RP (RP): percentage in TP in an institute and corresponding author articles.