Table 4 Final regression models US/MEX: EDF value is reported as the coefficient, and DF is included in parentheses (not standard errors because a chi-square test is used for the smooth terms)

Intercept

3.19*** (0.26)

2.44*** (0.22)

2.53*** (0.23)

2.46*** (0.23)

2.59*** (0.22)

2.22*** (0.20)

Per capita GDP

0.00*** (0.00)

0.00*** (0.00)

Socio-economic index

1.87*** (1.97)

1.78*** (1.92)

Active physicians per 1000

1.72** (1.90)

1.87*** (1.97)

1.88*** (1.98)

Households (%) with broadband access

1.94*** (1.99)

1.95*** (1.99)

1.95*** (1.99)

Quality of life index

1.78* (1.92)

1.00 (1.00)

1.00 (1.00)

Inter-regional migration rate

1.00*** (1.00)

1.65 (1.85)

1.61 (1.82)

Pop density growth

1.82 (1.96)

1.00*** (1.00)

1.00*** (1.01)

Percentage of population (65+)

1.97*** (1.99)

1.93*** (1.96)

1.79*** (1.89)

Mean temp (°C) of coldest quarter

1.90*** (1.98)

1.88*** (1.97)

1.83*** (1.95)

Precip of warmest quarter (in)

1.57* (1.81)

1.63* (1.84)

1.53** (1.76)

Year

7.27*** (8.00)

6.75*** (8.00)

6.99*** (8.00)

7.28*** (8.00)

6.61*** (8.00)

6.61*** (8.00)

Region

13.3*** (13.91)

12.76*** (13.72)

13.04*** (13.69)

12.72*** (13.81)

10.46*** (12.24)

10.45*** (12.19)

AIC

2339.82

2322.32

2332.83

2285.47

2233.10

2231.57

Deviance

1288.59

1205.43

1257.24

1143.83

967.55

962.59

Deviance explained

0.51

0.55

0.53

0.59

0.66

0.66

Dispersion

3.52

3.37

3.47

3.20

2.84

2.83

\(\text {R}^2\)

0.36

0.42

0.40

0.40

0.51

0.51

Num. obs.

306

306

306

306

306

306

Num. smooth terms

2

6

5

4

10

11