Research Article

Research on the Impact of Expressway on the County Economy Based on a Spatial DID Model: The Case of Three Provinces of China

Table 4

Parallel trend test results.

VariablesGuangdongHubeiQinghai

3 years prior−0.0447 (−1.61)−0.0394 (−1.68)−0.106 (−0.54)
2 years prior−0.015 (−0.41)−0.0309 (−0.97)0.0372 (0.19)
1 year prior−0.00822 (−0.17)−0.0401 (−1.25)0.099 (0.37)
Connect year0.0544 (1.20)−0.0285 (−1.04)0.105 (0.41)
1 year after−0.0117 (−0.37)−0.00143 (−0.05)−0.105 (−0.54)
2 years after0.0413 (1.29)0.000272 (0.01)−0.155 (−1.16)
3 years after0.0277 (0.96)−0.00641 (−0.23)−0.0496 (−0.74)
Constants14.41 (407.36)14.35 (385.88)12.22 (163.3)

Note. for , for , and for ; t statistics in parentheses.