Policy and Law Assessment of COVID-19 Based on Smooth Transition Autoregressive Model

Figure 9

The fitting result of Spain. The left axis shows the daily confirmed cases for the real data after smoothness (blue solid line) and its fitted values by the STAR model (blue dashed line). The right axis shows the value of nonlinear functions G changing with time (orange solid line) and the reference line with threshold 0.5 (orange dashed line). The vertical dotted line indicates the sequential released policies: ① restrict free traveling for 15 days, ② isolate residents at home and close nonessential places, ③ transform Madrid’s convention and exhibition center into a “makeshift hospital,” ④ force workers in noncore industries to stay at home, and ⑤ upgrade epidemic prevention and control measures.