Table 1.
Summary statistics of explanatory variables.
| Variable | Description | Mean | Std Dev | Min | Max |
|---|---|---|---|---|---|
| Dependent variable | |||||
| Flown | The number of operated flights | 59.88 | 140.77 | 0 | 2127 |
| Time-variant variables | |||||
| COVID14 | Dummy variable: 1 if the departure city has confirmed cases in the past 14 days, 0 otherwise | 0.39 | 0.49 | 0 | 2997 |
| D_COVID14 | The network effect of COVID-19 cases in destination cities | 0.59 | 0.34 | 0 | 1 |
| Level 1 | Dummy variable: 1 if a city imposes a level 1 response, 0 otherwise (reference) | 0.39 | 0.49 | 0 | 1 |
| Level 2 | Dummy variable: 1 if a city imposes a level 2 response, 0 otherwise | 0.17 | 0.38 | 0 | 1 |
| Level 3 | Dummy variable: 1 if a city imposes a level 3 response, 0 otherwise | 0.40 | 0.49 | 0 | 1 |
| Lockdown | Dummy variable: 1 if a city imposes a lockdown, 0 otherwise | 0.02 | 0.14 | 0 | 1 |
| FreerefundFeb11 | Dummy variable: 1 is assigned to dates from February 11 to March 31, and 0 otherwise | 0.48 | 0.50 | 0 | 1 |
| Time-invariant variables | |||||
| LnPop | Logarithm of the population size (unit: 10,000) | 5.96 | 0.78 | 3.73 | 8.05 |
| LnGDPpercap | Logarithm of GDP per capita (unit: yuan) | 1.74 | 0.56 | 0.52 | 3.00 |
| HubTop10 | Dummy variable: 1 if it is the city where the top ten airport hubs are located, 0 otherwise | 0.05 | 0.22 | 0 | 1 |
Note: The adjustment time of the response level of each province is shown in Fig. 3.