Table 2 Results of OLS regressions using the diff-in-diff specification

Luohu HMO х1st post-integration period

− 0.00803

[− 0.0337, 0.0177]

477.9

[− 2150.3, 3106.1]

0.279

[− 1.232, 1.789]

Luohu HMO х2nd post-integration period

0.00395

[− 0.0190, 0.0269]

− 291.5

[− 2365.6, 1782.7]

0.294

[− 0.809, 1.397]

Luohu HMO х3rd post-integration period

0.0172

[− 0.00771, 0.0421]

90.34

[− 2410.6, 2591.3]

− 0.693

[− 2.012, 0.627]

Luohu HMO х4th post-integration period

0.00776

[− 0.0155, 0.0310]

− 2032.8^*

[− 3912.9, − 152.8]

− 1.356^**

[− 2.211, − 0.501]

1st post-integration period

− 0.00666^*

[− 0.0130, − 0.000300]

446.0

[− 198.2, 1090.1]

− 0.0524

[− 0.342, 0.237]

2nd post-integration period

− 0.00665^*

[− 0.0121, − 0.00117]

86.49

[− 409.3, 582.3]

− 0.486^***

[− 0.715, − 0.257]

3rd post-integration period

− 0.0126^***

[− 0.0188, − 0.00647]

651.8^*

[79.79,1223.9]

− 0.0298

[− 0.296, 0.236]

4th post-integration period

− 0.00721^*

[− 0.0128, − 0.00167]

441.3

[− 17.52, 900.2]

− 0.390^***

[− 0.589, − 0.191]

Luohu HMO Indicator

− 0.0115

[− 0.0296,0.00659]

− 5302.3^***

[− 7089.4,-3515.1]

0.548

[− 0.553,1.649]

N

120,801

120,801

120,801