Massive Open Online Courses : A Bibliometric Review

Massive Open Online Courses (MOOCs) are open courses offered to an indefinite number of participants and accessible through virtual learning environments. These courses have been the subject of research all over the world. The purpose of this paper is to analyze the scientific production on Massive Open Online Courses in journals indexed in Clarivate Analytics’ Web of Science and Elsevier’s Scopus. The sample is composed by 1908 articles in total. The results obtained by bibliometric analysis showed that the publication continue to increase, in which journals they are published, which are the organizations and countries that publish the most, and which are the most cited articles. We concluded that since Massive Open Online Courses are a reality, there still seems to be a possibility for evolution in good quality publications.


I. INTRODUCTION
Massive Open Online Courses (MOOCs) are courses aimed at unlimited participation worldwide and open access via the web [1], classes delivered in an online environment, free and open to all, which attract substantially larger audiences than traditional online education [2]. The term was first used to describe an open online course "Connectivism and Connective Knowledge (CCK08)", which was developed at the University of Manitoba by George Siemens and Stephen Downes and had over 2200 participants from all over the world [3]. In 2011, the University of Pennsylvania, Princeton University, Stanford University and the University of Michigan joined forces to offer free courses online. The Massachusetts Institute of Technology and Harvard University came together to do the same in 2012. That partnership has expanded to include a number of other institutions, including the University of California at Berkeley and Wellesley College [4].
MOOCs have bifurcated into two types of course, which are known as cMOOCs and xMOOCs [5]. CMOOCs are constructivist MOOCs, like the early MOOCs that tended to have a decentralized, network-based, non-linear structure focused on exploration and conversation rather than emphasizing instructor-provided content. XMOOCs were hyper-centralized, content-based, and linear, typically focused around a set of short, modularized video-lectures, followed by automated, multiple-choice testing of learners' understanding of the content [3]. A MOOC brings together people interested in learning (or "students") and an expert or experts who seek to facilitate the learning [6], but Jordan [7] calculated that only 6.5% complete the course, with the Manuscript received Mar 30, 2020; revised January 23, 2021. Sónia Rolland Sobral is with REMIT, Universidade Portucalense, Porto, Portugal (e-mail: sonia@upt.pt). decrease of enrolment numbers positively correlated with course length.
Ye Zheng and Ruo-Yu Yang [8] selected 445 papers on educational study of MOOCs from the "Chinese Social Science Citation Index (CSSCI)" from 2013 to 2016 for a Bibliometric Analysis. A study [9] provided a systematic and organized review of 32 studies regarding using of Massive Open Online Courses (MOOCs) in Malaysian higher education from 2012 to 2017. Liyanagunawardena, Adams, Williams [6] presented a systematic review of the published MOOC literature (2008-2012): forty-five peer reviewed papers are identified through journals, database searches, Web searching and chaining from known sources to form the base for this review. Lambert [10] presents the results of a systematic review of literature of a set of 46 studies and reports from 2014 to 2018. Moreno-Marcos et al. [11] selected 88 papers to survey the state of the art on prediction in MOOCs through a systematic literature review.
All of these studies are important to give clues on how research in this area has been carried out and eventually to predict the future. This study provides insights not previously identified or evaluated in such detail using bibliometric indicators since the first articles were published until the year 2019. Bibliometric analysis [12] is the quantitative study of bibliographic material: provides a general picture of a research field that can be classified by papers, authors and journals. Bibliometric methods employ a quantitative approach for the description, evaluation, and monitoring of published research. These methods have the potential to introduce a systematic, transparent, and reproducible review process and thus improve the quality of reviews [13]. Bibliometric analysis provides objective criteria that can assess the research development in a field and act as a valuable tool for measuring scholarship quality and productivity [14]. Bibliometric methods offer systematization and replication processes that can improve understanding of the dissemination of knowledge in a field and can highlight gaps and opportunities that contribute to the advancement of the discipline [15].
The aim of this study is to conduct a literature review of the Massive Open Online Courses (MOOCs) research using bibliometric methods. The next section presents the research questions. The methodology is defined in the third section. Then the results are presented and at the end they are discussed and the conclusion is made.

II. THE RESEARCH QUESTION
The question, along with the purpose of the review, the intended deliverables and the intended audience, determines how the data are identified, collected and presented [16]. There are several questions that we want to answer in this

III. METHODOLOGY
The term bibliometrics was first used in 1969 by Alan Pritchard, hopping that the term would be explicitly used in all studies which seeked to quantify the processes of written communication and that it would quickly gain acceptance in the field of information science [17]. Moed mentioned the potential of this type of study that reveals the enormous potential of quantitative, bibliometric analyses of the scholarly literature for a deeper understanding of scholarly activity and performance, and highlighted their policy relevance [18]. In scientific research, it is important to get a wider perspective of research already being conducted concerning a relevant subject matter [19] and a bibliometric analysis profile on the research trajectory and dynamics of the research activities across the globe [20]. This is a bibliometric study that systematically analyses the literature using articles indexed at Elsevier"s Scopus (Scopus) and Clarivate Analytics" Web of Science (WoS) databases. This paper conducts a bibliometric analysis of international journal papers that we expect to provides a useful reference for future research.

IV. RESULTS
A set of 1479 published papers were collected from WoS and 1381 from SCOPUS. The search returned a total of 1908 articles and reviews after discounting the duplicate results.   The following figure shows the network visualization of the keywords (Fig. 3. Network visualization, keywords.). It is possible to verify that there are 4 keywords clusters:    (Table II. Authors with more articles.). Four of these authors are affiliated with Spanish universities, three with universities in the United States, one in Taiwan and the other in Canada. The network visualization (Fig. 5. Network visualization, Authors.) shows that there are groups but that do not seem significant because there are not many networks.
There are authors from 87 countries. The countries with the largest number of articles are: United States (21%), China (13%), Spain (11%), United Kingdom (8%) and Australia (5%). There are 15 countries that are responsible for at least 15 papers (Fig. 6. Countries with at least 15 papers.). This density of countries is clearly visible in Fig. 7. Density visualization, Countries.
There are contributions from 586 organizations: ten of these organizations have more than ten articles: the first three from United States, Indiana University, Massachusetts Institute of Technology and Harvard University (Table III. Organizations with more references.). We did not find clusters in organizations.     Since we had not used the language exclusion criterion, we can now see that English is used in 92% of the articles (Fig. 5. Language articles.). The other languages are Spanish with 5%, French, Italian and Chinese with 1% each and German, Hungarian, Japanese, Korean, Portuguese and Russian with less than 1% each. In the following table (Table IV. Most cited papers.) we list ten most cited papers. There is an author who has two articles in the list of the ten most cited articles: Rita Kop from Yorkville University, Fredericton, Canada. One of these articles the author writes alone, in the other article she co-writes with Hé lè ne Fournier (National Research Council Canada, Ottawa ON,, Canada) and with John Sui Fai Mak (Australia).
The authors of the ten most cited articles work in nine different countries, with the United Kingdom, United States and Canada being the most frequent countries (Fig. 9. Affiliation countries, most cited articles.). Bibliometric results indicate that Massive Open Online Courses is still a topic with a tendency to increase in number and quality of scientific production.

CONFLICT OF INTEREST
This study was carried out without a conflict of interest.

AUTHOR CONTRIBUTIONS
The author did a literature review, defined the methodology, research and data treatment, data analysis and conclusions, having written the entire document.