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

Figure 11

The fitting result of America. 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 declare state of emergency and close schools, ② impose travel ban to the United Kingdom and Ireland, ③ close the border with Canada, ④ close the border with Mexico, and ⑤ restart the US economy in three stages.