Table 2. Granger causality test results for delta and omicron variants.
| Null hypothesis | Quarantine | Lags, wk | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | 2 | 3 | 4 | 10 | |||||||
| F-statistic | P value | F-statistic | P value | F-statistic | P value | F-statistic | P value | F-statistic | P value | ||
| DEO does not Granger-cause DEN | 14 days | 1.397 | 0.246 | 0.613 | 0.549 | 1.047 | 0.389 | 1.088 | 0.386 | 8.584 | 0.014* |
| DEN does not Granger-cause DEO | 14 days | 0.093 | 0.762 | 0.108 | 0.898 | 0.637 | 0.598 | 0.610 | 0.660 | 0.530 | 0.816 |
| DEO does not Granger-cause DEN | 10 days | 1.487 | 0.231 | 1.163 | 0.325 | 1.761 | 0.525 | 1.589 | 0.281 | 2.248 | < 0.001** |
| DEN does not Granger-cause DEO | 10 days | 0.101 | 0.752 | 0.063 | 0.939 | 1.019 | 0.398 | 1.721 | 0.174 | 6.995 | < 0.001** |
| OMO does not Granger-cause OMN | 7 or 10 days | 4.314 | 0.050* | 6.978 | 0.010** | 2.646 | 0.113 | 4.829 | 0.044* | - | - |
| OMN does not Granger-cause OMO | 7 or 10 days | 13.851 | 0.002** | 5.173 | 0.024* | 2.338 | 0.142 | 2.517 | 0.150 | - | - |
| OMO does not Granger-cause OMN | Released | 0.682 | 0.433 | 14.989 | 0.008** | 14.499 | 0.065 | - | - | - | - |
| OMN does not Granger-cause OMO | Released | 0.157 | 0.703 | 1.803 | 0.257 | 4.919 | 0.174 | - | - | - | - |
DEO = delta virus from overseas entrants, DEN = delta virus national outbreaks, OMO = omicron virus from overseas entrants, OMN = omicron virus in national outbreaks.
*Indicates significance at P < 0.05; **Indicates significance at P < 0.01.