| Variables | Mixed OLS Model | SDM-based SDID Model | ||||
|---|---|---|---|---|---|---|
| (1) | (2) | (3) | (4) | (5) | (6) | |
| ADA | 0.0353*** (0.0074) | 0.0065* (0.0037) | ||||
| BR | 0.0445*** (0.0106) | 0.0283*** (0.0063) | ||||
| HR | 0.0373*** (0.0078) | 0.0061* (0.0033) | ||||
| SE | 0.0083 (0.0321) | 0.0165 (0.0322) | 0.0092 (0.0321) | 0.0338*** (0.0149) | 0.0378** (0.0148) | 0.0349*** (0.0149) |
| RA | -0.0257 (0.0329) | -0.0345 (0.0329) | -0.0214 (0.0331) | 0.0007 (0.0314) | 0.0035 (0.0306) | -0.0019 (0.0311) |
| TS | -0.05654** (0.0253) | -0.0466* (0.0252) | -0.0516** (0.0252) | 0.0228 (0.0227) | 0.0178 (0.0225) | 0.0229 (0.0226) |
| CA | 0.0422*** (0.0156) | 0.0413*** (0.0156) | 0.0451*** (0.0156) | -0.0077 (0.0142) | -0.0113 (0.0141) | -0.0075 (0.0141) |
| IE | 0.0539*** (0.0095) | 0.0584*** (0.0094) | 0.0522*** (0.0095) | -0.0189*** (0.0066) | -0.0202*** (0.0066) | -0.0169*** (0.0066) |
| W ADA | 0.1597*** (0.0571) | |||||
| W BR | 0.3073*** (0.0923) | |||||
| W HR | 0.2418*** (0.0554) | |||||
| W SE | -0.0696 (0.1001) | 0.0774 (0.1039) | 0.0408 (0.0994) | |||
| W RA | 1.0822*** (0.3689) | 0.6714** (0.3181) | 1.2121*** (0.3511) | |||
| W TS | -0.1786 (0.3061) | -0.3325 (0.3012) | -0.0722 (0.3062) | |||
| W CA | 0.0816 (0.2196) | -0.0012 (0.2191) | -0.0352 (0.2206) | |||
| W IE | 0.0567 (0.0821) | -0.0005 (0.0828) | 0.1507* (0.0845) | |||
| cons | 0.5196*** (0.0257) | 0.5147*** (0.0258) | 0.5168*** (0.0257) | |||
| City FE | No | No | No | Yes | Yes | Yes |
| Year FE | No | No | No | Yes | Yes | Yes |
| R2 | 0.1392 | 0.1365 | 0.1390 | 0.0104 | 0.0324 | 0.0105 |
| Observations | 1644 | 1644 | 1644 | 1644 | 1644 | 1644 |
Figure 2 The geographic location of cities that implemented administrative division adjustment between 2013 and 2018
Figure 4 The spatiotemporal evolution of urban polycentricity in China in different years: (a) 2013, (b) 2014, (c) 2015, (d) 2016, (e) 2017 and (f) 2018