Table 4.
Estimates of the relationship between natural balance (crude rate) and population density (log-transformed) using parametric (left) and nonparametric (right) approaches; F-test was always significant at p < 0.05
| Year | Polynomial fit | LOWESS spline | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| a | b | C | F-test | AIC | Max(d) | Max(n) | Window | Max(d) | Max(n) | |
| 1956 | − 0.44 | 2.59 | − 0.35 | 7.9 | 177 | 877 | 3.46 | 9.13 | 631 | 3.36 |
| 1960 | − 0.44 | 2.78 | − 1.01 | 13.1 | 140 | 1442 | 3.38 | 8.73 | 2455 | 3.23 |
| 1970 | − 0.39 | 2.54 | − 1.13 | 13.0 | 113 | 1803 | 3.01 | 8.70 | 3467 | 2.84 |
| 1980 | − 0.41 | 2.79 | − 1.99 | 17.4 | 99 | 2524 | 2.76 | 9.00 | 1738 | 2.54 |
| 1990 | − 0.34 | 2.15 | − 1.58 | 6.9 | 61 | 1452 | 1.82 | 9.38 | 1778 | 1.58 |
| 1999 | − 0.32 | 1.96 | − 1.45 | 6.9 | 41 | 1156 | 1.55 | 9.53 | 1380 | 1.42 |
| 2009 | − 0.43 | 2.53 | − 1.78 | 8.1 | 57 | 875 | 1.94 | 9.00 | 661 | 1.78 |
| 2019 | − 0.18 | 1.11 | − 0.76 | 5.3 | 21 | 1210 | 0.95 | 8.75 | 708 | 0.87 |