Table 5.
Partial regression coefficients estimated using ridge regression analysis.
| Crop Area | Estimation Method | μ′ | β 1 | β 2 | β 3 | γ |
|---|---|---|---|---|---|---|
| Early-maturing, single-cropping rice area in Northeast China | OLS | 5.39 *** 1 | 0.36 ** | −0.14 | 0.35 *** | −0.05 |
| RR (k = 0.19) | 6.55 *** | 0.18 | 0.05 *** | 0.11 *** | 0.02 | |
| Japan rice area | OLS | 7.39 *** | 0.07 | −0.37 | −0.17 | 0.93 *** |
| RR (k = 0.08) | 7.23 *** | −0.03 | −0.24 * | −0.13 | 0.82 *** | |
| Korea rice area | OLS | 7.44 *** | −0.17 | 0.08 | −0.01 | 0.35 *** |
| RR (k = 0.15) | 8.19 *** | −0.07 ** | −0.06 | −0.04 | 0.32 *** | |
| Spring maize area in northern China | OLS | 26.64 *** | −0.61 | 0.15 | 0.10 | −2.86 *** |
| RR (k = 0.15) | 25.62 *** | −0.73 ** | 0.11 *** | 0.12 ** | −2.42 *** | |
| Maize area in hilly southern China | OLS | 3.99 | 0.06 | 0.31 ** | 0.45 *** | −0.24 |
| RR (k = 0.12) | 7.38 *** | −0.18 ** | 0.21 *** | 0.32 *** | −0.17 | |
| Irrigated maize area in Northwest China | OLS | 8.71 *** | −0.34 | 0.06 | 0.36 ** | −0.04 |
| RR (k = 0.19) | 8.20 *** | −0.14 | 0.13 *** | 0.19 *** | −0.27 |
1. ***, **, and * indicate that the coefficient is significant at 1%, 5%, and 10%, respectively.