Research Trends in the International Literature on Natural Language Processing, 2000-2019 — A Bibliometric Study

This work presents a review, using bibliometric methods, of the state of research on the whole field of natural language processing (NLP), understanding this as the methods to process human language, including semantic techniques, statistical techniques or a combination of both. Particularly we focus on the trends of research in NLP, since there are not in the literature studies that embrace in an integral way bibliometric studies about natural language processing, its applications and related topics. Our work includes an identification of the main sources where research is published, the most productive and influential countries and research institutions, the main actors involved in research, as well as the main topics that are investigated. We found that research in the field and subfields has increased continuously during the period under study; conference proceedings are the preferred media to communicate results and that biomedical informatics is one relevant field of application of NLP. We conclude with both, a synchronic and a diachronic characterization of research topics carried out internationally on natural language processing and related topics, which showed that several subfields of artificial intelligence are closely related to natural language processing in recent years.