Visual conceptualizations and models of science

This is the Guest Editor's introduction to the Special Issue on “Science of Science: Conceptualizations and Models of Science”, Journal of Informetrics. The introduction discusses challenges towards a theoretically grounded and practically useful science of science. It provides a brief chronological review of relevant work and argues for (1) the development of common frameworks for the comparison and combination of existing approaches, theories, laws, and measurements, (2) the combination of quantitative and qualitative studies of science, and (3) the operationalization of theoretical concepts in terms of measurement and empirical evidence. Next, three visual conceptualizations of science are discussed and compared. Each of them provides a framework for the comparison and combination of existing works, means to combine quantitative and qualitative data, and helps to operationalize and communicate theoretical concepts using empirical data. Last but not least, the contributions of and interlinkages among the papers included in this issue are discussed.