Table 12 Robustness check (July 1, 2018, to December 31, 2019)

  γ_{i, 11}

−0.028 (− 0.552)

−0.194*** (− 4.011)

−0.046 (− 0.934)

  γ_{i, 12}

0.359*** (5.928)

− 0.100*** (− 3.323)

0.317*** (4.275)

  γ_{i, 21}

5.627 × 10^− 3 (− 0.166)

−0.012 (− 0.201)

8.246 × 10^− 3 (0.280)

  γ_{i, 22}

−0.075 (− 1.250)

−0.045 (− 0.765)

−0.063 (− 1.014)

  a_{i, 12}

0.140** (2.382)

0.056 (0.975)

−0.042 (− 1.168)

  a_{i, 21}

0.058 (0.332)

− 0.015 (− 0.483)

−0.100 (− 1.485)

  b_{i, 12}

−0.169** (− 2.329)

0.046 (0.328)

0.024*** (3.080)

  b_{i, 21}

0.234 (1.569)

− 0.045 (− 0.529)

−0.044** (− 1.985)

  d_{i, 12}

0.119* (1.931)

0.415*** (5.666)

0.191*** (6.026)

  d_{i, 21}

0.273** (2.290)

0.046 (1.303)

−0.174** (− 2.156)

  The US to China

(a_{i, 21} = b_{i, 21} = d_{i, 21} = 0)

3.540** [0.014]

0.760* [0.516]

2.784** [0.039]

  China to the US

(a_{i, 12} = b_{i, 12} = d_{i, 12} = 0)

16.011*** [0.000]

11.737*** [0.000]

19.234*** [0.000]