TABLE 3.

Gompertz postreproductive relative hazards of death (upper panel) in Old Quebec, Saguenay-Lac-St-Jean (SLSJ), and Utah accounting for sample selection bias (lower panel) and using the two-stage Heckman sample selection procedure

Gompertz model	Old Quebec		SLSJ		Utah
	Hazard ratio	P-value	Hazard ratio	P-value	Hazard ratio	P-value
First birth interval	1.034	0.157	1.092	0.053	1.003	0.029
Age at first birth	1.004	0.373	1.011	0.282	0.985	0.002
Age at last birth (a)	0.962	<0.001	0.953	0.005	0.966	<0.001
Total parity (b)	1.041	0.002	1.057	0.077	1.063	<0.001
Interaction a × b	0.998	0.010	0.997	0.062	0.998	0.007
Infant mortality low (=1 if <20%)	0.843	<0.001	0.811	0.015	0.822	0.038
Birth year	0.998	0.003	1.001	0.750	0.995	<0.001
Age at death ofspouse	0.995	<0.001	1.002	0.516	0.996	<0.001
Immigrant	0.882	0.072	0.898	0.079
Urban residence	1.295	<0.001	0.793	<0.001
Live in the West	0.831	<0.001
LDS					0.801	<0.001
Inverse Mill’s ratio (IMR)	0.527	0.023	0.546	0.382	0.046	0.001
Gamma	0.088	<0.001	0.090	<0.001	0.123	<0.001
Theta	0.030	0.037	0.031	0.173	0.223	<0.001
N	5,477		1,610		11,395
Selection model	Probit	P-value	Probit	P-value	Probit	P-value
Age at marriage	0.033	<0.001	0.030	<0.001	0.016	<0.001
First birth interval	−0.068	0.001	− 0.046	0.314	− 0.001	0.697
Mean birth interval	0.244	<0.001	0.279	<0.001	0.061	<0.001
Infant mortality low (=1 if <20%)	0.130	<0.001	0.241	<0.001	0.179	0.006
Birth year	− 0.002	<0.001	− 0.003	0.196	0.001	0.073
Immigrant	0.158	0.002	− 0.026	0.679
Urban	− 0.223	<0.001	0.025	0.697
West	0.121	<0.001
LDS					0.126	<0.001
Intercept	2.240	0.008	5.023	0.277	− 2.262	0.105
N	10,114		2,365		13,739