Application of semi-logarithmic line graph in epidemiological research

This paper introduces the structure and application of semi-logarithmic line chart, and studies the time distribution of novel coronavirus disease 2019 (COVID-19) epidemic in China by using semi-logarithmic line chart, and analyzes the change of epidemic speed of COVID-19. According to the analysis of the time distribution of COVID-19 patients in the late January 2020, the transmission speed of the COVID-19 patients was obviously decreased, the semi-logarithmic line was gradually flattened, and the daily link ratio (DLR) was close to one. Prevention and control measures are very effective. If the prevention and control during the return period of the Spring festival is proper, the epidemic is expected to gradually decline. The semi-logarithmic line graph is an important tool to study the law of epidemic fluctuation.