Decreasing diversity in Japanese science, evidence from in-depth analyses of science maps

This study aimed to monitor the status of scientific research in Japan, especially the diversity of scientific research, based on in-depth analyses of science maps. Analyses of six consecutive maps showed decreasing diversity in Japanese science relative to benchmarking countries. We proposed a new concept for a Sci-GEO chart (representing geographical characteristics of research areas on a science map) that aims to classify research areas in terms of continuity and cognitive linkage. Based on the Sci-GEO chart, we classified research areas into four Sci-GEO types, i.e., small island, island, peninsula, and continent, and analysed their properties, such as size and transitions across Sci-GEO types. Our analyses showed that Japanese science put more weight on continent-type research (stable and well-established research), compared with benchmarking countries, and the lack of diversity is attributable to low coverage of small island-type research (research areas with active replacement). We also demonstrated that the Sci-GEO chart well represented the funding characteristics and strategy of two major competitive funding agencies in Japan, and the chart provides policymakers and government officials with baseline information for the planning of science and technology policy.