Pre COVID-19 (01 December 2018 to 31 December 2020) | COVID-19 (13 January 2020 to 01 April 2020) | |||
---|---|---|---|---|
Coefficient | P value | Coefficient | P value | |
Panel A. Mean equation | ||||
\(\mu_{1}\) | − 0.000 | 0.406 | 0.000 | 0.142 |
\(\emptyset_{11}\) | − 0.134a | 0.000 | − 0.115b | 0.028 |
\(\emptyset_{12}\) | − 0.001 | 0.908 | 0.074c | 0.097 |
\(\emptyset_{13}\) | 0.113c | 0.073 | 0.037 | 0.569 |
\(\mu_{2}\) | − 0.001 | 0.170 | 0.000b | 0.012 |
\(\emptyset_{21}\) | 0.043b | 0.016 | 0.024 | 0.505 |
\(\emptyset_{22}\) | − 0.089a | 0.001 | − 0.182a | 0.001 |
\(\emptyset_{23}\) | 0.148a | 0.000 | 0.112b | 0.048 |
\(\mu_{3}\) | − 0.000 | 0.305 | 0.000 | 0.317 |
\(\emptyset_{31}\) | 0.019 | 0.103 | 0.026 | 0.236 |
\(\emptyset_{32}\) | 0.032c | 0.060 | 0.011 | 0.745 |
\(\emptyset_{33}\) | − 0.196a | 0.000 | − 0.258a | 0.000 |
Panel B. Variance equation | ||||
\(c_{1}\) | 0.001a | 0.000 | 0.000a | 0.000 |
\(c_{2}\) | 0.000b | 0.016 | 0.000a | 0.000 |
\(c_{3}\) | 0.000b | 0.032 | 0.001a | 0.001 |
\(a_{11}\) | 0.124a | 0.001 | − 0.022c | 0.094 |
\(a_{12}\) | 0.011b | 0.032 | 0.079a | 0.000 |
\(a_{13}\) | 0.019b | 0.013 | − 0.003c | 0.086 |
\(a_{21}\) | 0.019 | 0.115 | − 0.072a | 0.000 |
\(a_{22}\) | 0.031c | 0.051 | 0.186a | 0.000 |
\(a_{23}\) | 0.014b | 0.033 | 0.012c | 0.053 |
\(a_{31}\) | 0.018 | 0.548 | − 0.108a | 0.002 |
\(a_{32}\) | 0.001 | 0.736 | 0.172a | 0.003 |
\(a_{33}\) | 0.155a | 0.001 | 0.059b | 0.050 |
\(b_{11}\) | 0.864a | 0.000 | 0.986a | 0.000 |
\(b_{12}\) | − 0.036b | 0.027 | 0.016b | 0.042 |
\(b_{13}\) | − 0.022 | 0.290 | 0.075a | 0.000 |
\(b_{21}\) | − 0.024c | 0.075 | 0.028b | 0.033 |
\(b_{22}\) | 0.953a | 0.000 | 0.885a | 0.000 |
\(b_{23}\) | − 0.010 | 0.135 | − 0.060a | 0.000 |
\(b_{31}\) | − 0.035 | 0.443 | 0.028 | 0.169 |
\(b_{32}\) | 0.277c | 0.099 | 0.115c | 0.084 |
\(b_{33}\) | 0.636a | 0.000 | 0.522a | 0.000 |
\(d_{1}\) | − 0.052b | 0.050 | 0.041 | 0.070 |
\(d_{2}\) | − 0.018b | 0.025 | 0.030c | 0.093 |
\(d_{3}\) | − 0.103a | 0.000 | 0.064b | 0.032 |
Panel C: Constant correlations | ||||
\(p_{21}\) | 0.783a | 0.000 | 0.869a | 0.000 |
\(p_{31}\) | 0.658a | 0.000 | 0.803a | 0.000 |
\(p_{32}\) | 0.710a | 0.000 | 0.831a | 0.000 |
Panel D: Robustness tests | ||||
Log L | 10,711.7 | 18,493.2 | ||
AIC | − 21.416 | − 20.046 | ||
SIC | − 21.268 | − 19.467 | ||
\(Q_{1}\)(20) | 31.675b | 0.046 | 33.334b | 0.030 |
\(Q_{2}\)(20) | 39.436a | 0.005 | 33.455b | 0.030 |
\(Q_{3}\)(20) | 25.676 | 0.176 | 22.340 | 0.322 |
\(Q_{1}^{2}\)(20) | 2.916 | 0.997 | 14.670 | 0.672 |
\(Q_{2}^{2}\)(20) | 4.055 | 0.989 | 11.778 | 0.740 |
\(Q_{3}^{2}\)(20) | 6.238 | 0.988 | 16.621 | 0.802 |