Estimation of COVID-19 Cases in Japanese Prefectures Using a Gumbel Distribution
Author(s): Hiroshi Furutani, Tomoyuki Hiroyasu
Applying a model from extreme value theory (EVT), we provide a statistical study for the estimation of the daily number of COVID-19 infections in Japan. The present study is carried out from a regional viewpoint. Selecting 16 prefectures from among the 47 prefectures of Japan, we obtain the regional growth rate of infection and the point of inflection. Among three fundamental functions of EVT, we use the Gumbel distribution function and estimate model parameters by fitting daily new cases in the 16 prefectures. The biggest advantage of the present method is its simplicity and straightforward- ness, which allow us to obtain preliminary results and an overall image of infection trends without using complicated mathematical tools.